[Federal Register Volume 65, Number 121 (Thursday, June 22, 2000)]
[Proposed Rules]
[Pages 38888-38983]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-13546]



[[Page 38887]]

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Part II





Environmental Protection Agency





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40 CFR Parts 141 and 142



National Primary Drinking Water Regulations; Arsenic and Clarifications 
to Compliance and New Source Contaminants Monitoring; Proposed Rule

  Federal Register / Vol. 65, No. 121 / Thursday, June 22, 2000 / 
Proposed Rules  

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 141 and 142

[WH-FRL-6707-2]
RIN 2040-AB75


National Primary Drinking Water Regulations; Arsenic and 
Clarifications to Compliance and New Source Contaminants Monitoring

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of proposed rulemaking.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing a 
drinking water regulation for arsenic, as required by the 1996 
amendments to the Safe Drinking Water Act (SDWA). The proposed health-
based, non-enforceable goal, or Maximum Contaminant Level Goal (MCLG), 
for arsenic is zero, and the proposed enforceable standard, or maximum 
contaminant level (MCL), for arsenic is 0.005 mg/L. EPA is also 
requesting comment on 0.003 mg/L, 0.010 mg/L and 0.020 mg/L for the 
MCL. EPA is listing technologies that will meet the MCL, including 
affordable compliance technologies for three categories of small 
systems serving less than 10,000 people. This proposal also includes 
monitoring, reporting, public notification, and consumer confidence 
report requirements and State primacy revisions for public drinking 
water programs affected by the arsenic regulation.
    In addition, in this proposal the Agency is clarifying compliance 
for State-determined monitoring after exceedances for inorganic, 
volatile organic, and synthetic organic contaminants. Finally, EPA is 
proposing that States will specify the time period and sampling 
frequency for new public water systems and systems using a new source 
of water to demonstrate compliance with the MCLs. The requirement for 
new systems and new source monitoring will be effective for inorganic, 
volatile organic, and synthetic organic contaminants.

DATES: EPA must receive public comments, in writing, on the proposed 
regulations by September 20, 2000. EPA will hold a public meeting on 
this proposed regulation this summer. EPA will publish a notice of the 
meeting, providing date and location, in the Federal Register, as well 
as post it on EPA's Office of Ground Water and Drinking Water web site 
at http://www.epa.gov/safewater.

ADDRESSES: You may send written comments to the W-99-16 Arsenic 
Comments Clerk, Water Docket (MC-4101); U.S. Environmental Protection 
Agency; 1200 Pennsylvania Ave., NW, Washington, DC 20460. Comments may 
be hand-delivered to the Water Docket, U.S. Environmental Protection 
Agency; 401 M Street, SW; EB-57; Washington, DC 20460; (202) 260-3027 
between 9 a.m. and 3:30 p.m. Eastern Time, Monday through Friday. 
Comments may be submitted electronically to [email protected]. 
See SUPPLEMENTARY INFORMATION for file formats and other information 
about electronic filing and docket review. The proposed rule and 
supporting documents, including public comments, are available for 
review in the Water Docket at the above address.

FOR FURTHER INFORMATION CONTACT: Regulatory information: Irene Dooley, 
(202) 260-9531, email: [email protected]. Benefits: Dr. John B. 
Bennett, (202) 260-0446, email: [email protected] General 
information about the regulation: Safe Drinking Water Hotline, phone: 
(800) 426-4791, or (703) 285-1093, email: [email protected].

SUPPLEMENTARY INFORMATION:

Regulated Entities

    A public water system, as defined in 40 CFR 141.2, provides water 
to the public for human consumption through pipes or other constructed 
conveyances, if such system has ``at least fifteen service connections 
or regularly serves an average of at least twenty-five individuals 
daily at least 60 days out of the year.'' A public water system is 
either a community water system (CWS) or a non-community water system 
(NCWS). A community water system, as defined in Sec. 141.2, is ``a 
public water system which serves at least fifteen service connections 
used by year-round residents or regularly serves at least twenty-five 
year-round residents.'' The definition in Sec. 141.2 for a non-
transient, non-community water system [NTNCWS] is ``a public water 
system that is not a [CWS] and that regularly serves at least 25 of the 
same persons over 6 months per year.'' EPA has an inventory totaling 
over 54,000 community water systems and approximately 20,000 non-
transient, non-community water systems nationwide. Entities potentially 
regulated by this action are community water systems and non-transient, 
non-community water systems. The following table provides examples of 
the regulated entities under this rule.

                       Table of Regulated Entities
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                                   Examples of potentially regulated
           Category                             entities
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Industry.....................  Privately owned/operated community water
                                supply systems using ground water or
                                mixed ground water and surface water.
State, Tribal, and Local       State, Tribal, or local government-owned/
 Government.                    operated water supply systems using
                                ground water or mixed ground water and
                                surface water.
Federal Government...........  Federally owned/operated community water
                                supply systems using ground water or
                                mixed ground water and surface water.
------------------------------------------------------------------------

    The table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be regulated by this 
action. This table lists the types of entities that EPA is now aware 
could potentially be regulated by this action. Other types of entities 
not listed in this table could also be regulated. To determine whether 
your facility is regulated by this action, you should carefully examine 
the applicability criteria in Secs. 141.11 and 141.62 of the rule. If 
you have any questions regarding the applicability of this action to a 
particular entity, consult Irene Dooley, the regulatory information 
person listed in the FOR FURTHER INFORMATION CONTACT section.

Additional Information for Commenters

    Please submit an original and three copies of your comments and 
enclosures (including references). To ensure that EPA can read, 
understand, and therefore properly respond to comments, the Agency 
would prefer that comments cite, where possible, the paragraph(s) or 
sections in the notice or supporting documents to which each comment 
refers. Commenters should use a separate paragraph for each issue 
discussed. Electronic comments must be submitted as a WordPerfect 5.1, 
WP6.1

[[Page 38889]]

or WP8 file or as an ASCII file avoiding the use of special characters. 
Comments and data will also be accepted on disks in WP5.1, WP6.1 or 
WP8, or ASCII file format. Electronic comments on this Notice may be 
filed online at many Federal Depository Libraries. Commenters who want 
EPA to acknowledge receipt of their comments should include a self-
addressed, stamped envelope. No facsimiles (faxes) will be accepted.

Availability of Docket

    The docket for this rulemaking has been established under number W-
99-16, and includes supporting documentation as well as printed, paper 
versions of electronic comments. The docket is available for inspection 
from 9 a.m. to 4 p.m., Monday through Friday, excluding legal holidays, 
at the Water Docket; EB 57; U.S. EPA; 401 M Street, SW; Washington, 
D.C. For access to docket materials, please call (202) 260-3027 to 
schedule an appointment.

Abbreviations Used in This Proposed Rule

>--greater than
--greater than or equal to
--less than
--less than or equal to
Sec. --Section
ACWA--Association of California Water Agencies
AA--activated alumina
As (III)--trivalent arsenic. Common inorganic form in water is arsenite
As (V)--pentavalent arsenic. Common inorganic form in water is arsenate
ATSDR--Agency for Toxic Substances and Disease Registry, U.S. 
Department of Health & Human Services
ASTM--American Society for Testing and Materials
ASV--anodic stripping voltammetry
AWQC--Ambient Water Quality Criterion
AWWA--American Water Works Association
BAT--best available technology
BFD--Blackfoot disease
BOD--biochemical oxygen demand
BOSC--Board of Scientific Counselors, ORD
CASRN--Chemical Abstracts Service registration number
CCA--chromated copper arsenate
CCR--consumer confidence report
CDC--Centers for Disease Control and Prevention
CFR--Code of Federal Regulations
CPI--Consumer Price Index
CSFII--Continuing Survey of Food Intakes by Individuals
CV--coefficient of variation=standard deviation divided by the mean  x  
100
CWS--community water system
CWSS--Community Water System Survey
DBPs--disinfection byproducts
DBPR--Disinfectants/Disinfection By-products Rule
DMA--Di-methyl arsinic acid, cacodylic acid, 
(CH3)2HAsO2
DSMA--Disodium methanearsonate
DWSRF--Drinking Water State Revolving Fund
DNA--Deoxyribonucleic acid
EB--East Tower Basement
EDL--Estimated Detection Limit
EDR--Electrodialysis Reversal
e.g.--such as
EJ--Environmental Justice
EO--Executive Order
EPA--U.S. Environmental Protection Agency
FDA--Food and Drug Administration
FR--Federal Register
FTE--full-time equivalents (employees)
GDP--Gross Domestic Product
GFAA--Graphite Furnace Atomic Absorption
GHAA--Gaseous Hydride Atomic Absorption
GI--gastrointestinal
gw--ground water
HRRCA--Health Risk Reduction and Cost Analysis
IARC--International Agency for Research on Cancer
ICP-MS--Inductively Coupled Plasma Mass Spectroscopy
i.e.--that is
ICP-AES--Inductively Coupled Plasma-Atomic Emission Spectroscopy
IESWTR--Interim Enhanced Surface Water Treatment Rule
IOCs--inorganic contaminants
IRFA--Initial Regulatory Flexibility Analysis
IRIS--Integrated Risk Information System
IX--Ion exchange
K--thousands
kg--kilogram, which is one thousand grams
L--Liter, also referred to as lower case ``l'' in older citations
LC50--The concentration of a chemical in air or water which 
is expected to cause death in 50% of test animals living in that air or 
water
LCP--laboratory certification program
LD50--The dose of a chemical taken by mouth or absorbed by 
the skin which is expected to cause death in 50% of the test animals so 
treated
LOAEL--Lowest-observed-adverse-effect level
LS--lime softening
LT2ESWTR--Long-Term 2 Enhanced Surface Water Treatment Rule
M--millions
m3--Cubic meters
MCL--maximum contaminant level
MCLG--maximum contaminant level goal
MDL--method detection limit
Metro--Metropolitan Water District of Southern California
mg--Milligrams--one thousandth of gram, 1 milligram = 1,000 micrograms
mg/kg--milligrams per kilogram
mg/m3--Milligrams per cubic meter
microgram (g)--One-millionth of gram (3.5  x  10-8 
oz., 0.000000035 oz.)
g/L--micrograms per liter
M/DBP--Microbial/Disinfection By-product
MMA--Mono-methyl arsenic, arsonic acid, 
CH3H2AsO3
MOS--margin of safety
MSMA--Monosodium methanearsonate
NAOS--National Arsenic Occurrence Survey
NAS--National Academy of Sciences
NAWQA--National Ambient Water Quality Assessment, USGS
NCI--National Cancer Institute
NCWS--non-community water system
NDWAC--National Drinking Water Advisory Council
NELAC--National Environmental Laboratory Accreditation Council
NIRS--National Inorganic and Radionuclide Survey
NIST--National Institute of Standards and Technology
NOAEL--No-observed-adverse-effect level
NODA--notice of data availability
NOEL--No-observed-effect level
NPDWR--National Primary Drinking Water Regulation, OGWDW
NRC--National Research Council, the operating arm of NAS
NTNCWS--non-transient non-community water system
NTTAA--National Technology Transfer and Advancement Act of 1995
NWIS--National Water Information System
O&M--operational and maintenance
OGWDW--Office of Ground Water and Drinking Water
PBMS--Performance-Based Measurement System
PE--performance evaluation, studies to certify laboratories for EPA 
drinking water testing
P.L.--Public Law
PNR--Public notification rule
POD--point of departure
POE--Point-of-entry treatment devices
POU--Point-of-use treatment devices
ppb--Parts per billion. Also, g/L or micrograms per liter
ppm--Parts per million. Also, mg/L or milligrams per liter
PQL--Practical quantitation level
PRA--Paperwork Reduction Act
PT--performance testing
PWS--Public water systems
PWSS--Public Water Systems Supervision
RCRA--Resource Conservation and Recovery Act

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REFs--relative exposure factors
RFA--Regulatory Flexibility Act
RfD--Reference dose
RIA--Regulatory Impact Analysis
RMCL--Recommended Maximum Contaminant Level
RO--reverse osmosis
RWS--Rural Water Survey
SAB--Science Advisory Board
SBA--Small Business Administration
SBREFA--Small Business Regulatory and Enforcement Flexibility Act, SBA
SDWA--Safe Drinking Water Act of 1974, as amended
SDWIS--Safe Drinking Water Information System
SER--Small Entity Representative for SBREFA
SISNOSE--Substantial impact on a significant number of small entities, 
SBREFA
SM--Standard Methods for the Examination of Water and Wastewater
SMRs--Standardized mortality ratios, comparing deaths in test areas to 
deaths in unexposed areas
SSCTs--Small System Compliance Technologies
STP-GFAA--Stabilized Temperature Platform Graphite Furnace Atomic 
Absorption
SW--Office of Solid Waste publication or test method
SW-846--Solid Waste publication #846, Test Methods for Solid and 
Hazardous Waste
TC--toxicity characteristic
TDS--total dissolved solids
TNC--transient, non-community
TOC--total organic carbon
g--Microgram, 1000 micrograms = 1 milligram
UMRA--Unfunded Mandates Reform Act
U.S.--United States
USDA--U.S. Department of Agriculture
USGS--U.S. Geological Survey
USPHS--U.S. Public Health Service
VSL--Value of Statistical Life
WESTCAS--Western Coalition of Arid States
WHO--World Health Organization
WITAF--Water Industry Technical Action Fund
WS--water supply
WTP--Willingness to pay

Table of Contents

I. Summary of Regulation
II. Background
    A. What is the Statutory Authority for the Arsenic Drinking 
Water Regulation?
    B. What is arsenic?
    C. What are the sources of arsenic exposure?
    1. Natural Sources of Arsenic
    2. Industrial Sources of Arsenic
    3. Dietary Sources
    4. Environmental Sources
    D. What is the regulatory history for arsenic?
    1. Earliest U.S. Arsenic Drinking Water Standards
    2. EPA's 1980 Guidelines
    3. Research and Regulatory Work
    E. EPA's Arsenic Research Plan
III. Toxic Forms and Health Effects of Arsenic
    A. What are the toxic forms of arsenic?
    B. What are the effects of acute toxicity?
    C. What cancers are associated with arsenic?
    1. Skin Cancer
    2. Internal Cancers
    D. What non-cancer effects are associated with arsenic?
    E. What are the recent developments in health effects research?
    1. Funding of Health Effects Research
    2. Expert Panel on Arsenic Carcinogenicity
    3. NAS Review of EPA's Risk Assessment
    4. May 1999 Utah Mortality Study
    5. 1999 Review of health effects
    6. Study of Bladder and Kidney Cancer in Finland
    F. What did the National Academy of Sciences/National Research 
Council report?
    1. The National Research Council and its Charge
    2. Exposure
    3. Essentiality
    4. Metabolism and Disposition
    5. Human Health Effects and Variations in Sensitivity
    6. Modes of Action
    7. Risk Considerations
    8. Risk Characterization
IV. Setting the MCLG
    A. How did EPA approach it?
    B. What is the MCLG?
    C. How will a health advisory protect potentially sensitive 
subpopulations?
    D. How will the Clean Water Act criterion be affected by this 
regulation?
V. EPA's Estimates of Arsenic Occurrence
    A. What data did EPA evaluate?
    B. What databases did EPA use?
    C. How did EPA estimate national occurrence of arsenic in 
drinking water?
    D. What are the national occurrence estimates of arsenic in 
drinking water for community water systems?
    E. How do EPA's estimates compare with other recent national 
occurrence estimates?
    F. What are the national occurrence estimates of arsenic in 
drinking water for non-transient, non-community water systems?
    G. How do arsenic levels vary from source to source and over 
time?
    H. How did EPA evaluate co-occurrence?
    1. Data
    2. Results of the Co-occurrence Analysis (US EPA, 1999f)
VI. Analytical Methods
    A. What section of SDWA requires the Agency to specify 
analytical methods?
    B. What factors does the Agency consider in approving analytical 
methods?
    C. What analytical methods and method updates are currently 
approved for the analysis of arsenic in drinking water?
    D. Will any of the approved methods for arsenic analysis be 
withdrawn?
    E. Will EPA propose any new analytical methods for arsenic 
analysis?
    F. Other Method-Related Items
    1. The Use of Ultrasonic Nebulization with ICP-MS
    2. Performance-Based Measurement System
    G. What are the estimated costs of analysis?
    H. What is the practical quantitation limit?
    1. PQL determination
    2. PQL for arsenic
    I. What are the sample collection, handling and preservation 
requirements for arsenic?
    J. Laboratory Certification
    1. Background
    2. What Are the Performance Testing criteria for arsenic?
    3. How often is a laboratory required to demonstrate acceptable 
PT performance?
    4. Externalization of the PT Program (formerly known as the PE 
Program)
VII. Monitoring and Reporting Requirements
    A. What are the existing monitoring and compliance requirements?
    B. How does the Agency plan to revise the monitoring 
requirements?
    C. Can States grant monitoring waivers?
    D. How can I determine if I have an MCL violation?
    E. When will systems have to complete initial monitoring?
    F. Can I use grandfathered data to satisfy the initial 
monitoring requirement?
    G. What are the monitoring requirements for new systems and 
sources?
    H. How does the Consumer Confidence Report change?
    I. How will public notification change?
VIII. Treatment Technologies
    A. What are the Best Available Technologies (BATs) for arsenic? 
What are the issues associated with these technologies?
    B. What are the likely treatment trains? How much will they 
cost?
    C. How are variance and compliance technologies identified for 
small systems?
    D. When are exemptions available?
    E. What are the small systems compliance technologies?
    F. How does the Arsenic Regulation overlap with other 
regulations?
IX. Costs
    A. Why does EPA analyze the regulatory burden?
    B. How did EPA prepare the baseline study?
    1. Use of baseline data
    2. Key data sources used in the baseline analysis for the RIA?
    C. How were very large system cost derived?
    D. How did EPA develop cost estimates?
    E. What are the national treatment costs of different MCL 
options?
    1. Assumptions affecting the development of the decision tree
    2. Assumptions affecting unit cost curves
X. Benefits of Arsenic Reduction
    A. Monetized Benefits of Avoiding Bladder Cancer
    1. Risk reductions: The Analytic Approach
    2. Water Consumption
    3. Monte Carlo Analysis
    4. Relative Exposure Factors
    5. NRC Risk Distributions

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    6. Estimated Risk Reductions
    B. ``What if?'' scenario for lung cancer risks
    C. Evaluation of Benefits
    1. Fatal Risks and Value of a Statistical Life (VSL)
    2. Nonfatal Risks and Willingness to Pay (WTP)
    D. Estimates of Quantifiable Benefits of Arsenic Reduction
    F. NDWAC Working Group (NDWAC, 1988) on Benefits
XI. Risk Management Decisions: MCL and NTNCWSs
    A. What is the Proposed MCL?
    1. Feasible MCL
    2. Principal Considerations in Analysis of MCL Options
    3. Findings of NRC and Consideration of Risk Levels
    4. Non-monetized Health Effects
    5. Sources of Uncertainty
    6. Comparison of Benefits and Costs
    7. Conclusion and Request for Comment
    B. Why is EPA proposing a total arsenic MCL?
    C. Why is EPA proposing to require only monitoring and 
notification for NTNCWSs?
    1. Methodology for analyzing NTNCWS risks
    2. Results
XII. State Programs
    A. How does arsenic affect a State's primacy program?
    B. When does a State have to apply?
    C. How are Tribes affected?
XIII. HRRCA
    A. What are the requirements for the HRRCA?
    B. What are the quantifiable and non-quantifiable health risk 
reduction benefits?
    C. What are the Quantifiable and Non-Quantifiable Costs?
    D. What are the Incremental Benefits and Costs?
    E. What are the Risks of Arsenic Exposure to the General 
Population and Sensitive Subpopulations?
    F. What are the Risks Associated with Co-Occurring Contaminants?
    G. What are the Uncertainties in the Analysis?
XIV. Administrative Requirements
    A. Executive Order 12866: Regulatory Planning and Review
    B. Regulatory Flexibility Act (RFA), as amended by the Small 
Business Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5 
U.S.C. 601 et seq.
    1. Overview
    2. Use of Alternative Small Entity Definition
    3. Initial Regulatory Flexibility Analysis
    a. Number of Small Entities Affected
    b. Reporting, Recordkeeping and Other Requirements for Small 
Systems
    4. Small Business Advocacy Review (SBAR) Panel Recommendations
C. Unfunded Mandates Reform Act (UMRA)
    1. Summary of UMRA Requirements
    a. Authorizing legislation
    b. Cost-benefit analysis
    c. Financial Assistance
    d. Estimates of future compliance costs and disproportionate 
budgetary effects
    e. Macroeconomic effects
    f. Summary of EPA's consultation with State, local, and tribal 
governments and their concerns
    g. Nature of State, local, and Tribal government concerns and 
how EPA addressed these concerns
    h. Regulatory Alternatives Considered
    2. Impacts on Small Governments
    D. Paperwork Reduction Act (PRA)
    E. National Technology Transfer and Advancement Act (NTTAA)
    F. Executive Order 12898: Environmental Justice
    G. Executive Order 13045: Protection of Children from 
Environmental Health Risks and Safety Risks
    H. Executive Order 13132: Federalism
    I. Executive Order 13084: Consultation and Coordination with 
Indian Tribal Governments
    J. Request for Comments on Use of Plain Language
XV. References
List of Tables
Table V-1. Summary of Arsenic Data Sources
Table V-2. Regional Exceedance Probability Distribution Estimates
Table V-3. Statistical Estimates of Number of Ground Water CWSs with 
Average Arsenic Concentrations in Specified Ranges
Table V-4. Statistical Estimates of Number of Surface Water CWSs 
with Average Arsenic Concentrations in Specified Ranges
Table V-5. Comparison of CWSs from EPA, NAOS, and USGS Estimates 
Exceeding Arsenic Concentrations
Table V-6. Statistical Estimates of Number of Ground Water NTNCWSs 
with Average Arsenic Concentrations in Specified Ranges
Table V-7. Statistical Estimates of Number of Surface Water NTNCWSs 
with Average Arsenic Concentrations in Specified Ranges
Table V-8. Correlation of Arsenic with Sulfate and Iron (surface and 
ground waters)
Table V-9. Correlation of Arsenic with Radon (ground water)
Table VI-1. Approved Analytical Methods (and Method Updates) for 
Arsenic (CFR 141.23)
Table VI-2. Estimated Costs for the Analysis of Arsenic in Drinking 
Water
Table VI-3. Acceptance Limits and PQLs for Other Metals (in order of 
decreasing PQL)
Table VII-1. Comparison of Sampling, Monitoring, and Reporting 
Requirements
Table VII-2. Treatment in-place at small water systems (US EPA, 
1999e and US EPA, 1999m)
Table VII-3. Table Identifying Regulatory Changes
Table VII-4. Table Listing Deleted Sections
Table VIII-1. Best Available Technologies and Removal Rates
Table VIII-2. Treatment Technology Trains
Table VIII-3. Annual Costs of Treatment Trains (Per household)
Table VIII-4. Affordable Compliance Technology Trains for Small 
Systems
Table VIII-5. Affordable Compliance Technology Trains for Small 
Systems
Table IX-1. Summary of General Baseline Categories of Affected 
Entities
Table IX-2. List of Large Water Systems that Serve More Than 1 
Million People
Table IX-3. Total Annual Costs for Large Systems for (serving more 
than 1 million people)
Table IX-4. Systems Needing to Add Pre-Oxidation
Table IX-5. Percent of Systems with Coagulation-Filtration and Lime-
Softening in Place
Table IX-6. Waste Disposal Options
Table IX-7. Ground Water: Arsenic and Sulfate
Table IX-8. Surface Water: Arsenic and Sulfate
Table IX-9. Ground Water: Arsenic and Iron
Table IX-10. Surface Water: Arsenic and Iron
Table IX-11. National Annual Treatment Costs (Dollars in Millions)
Table IX-12. Total Annual Costs per Household (Dollars)
Table IX-13. Incremental National Annual Costs (Dollars in Millions)
Table IX-14. Incremental Annual Costs per Household (Dollars)
Table X-1. Source of Water Consumed
Table X-2a. Bladder Cancer Incidence Risks \1\ for High Percentile 
U.S. Populations Exposed At or Above MCL Options, After Treatment 
\2\ (Community Water Consumption Data \3\)
Table X-2b. Bladder Cancer Incidence Risks1 for High Percentile U.S. 
Populations Exposed At or Above MCL Options, After Treatment \2\ 
(Total Water Consumption Data \3\)
Table X-3a. Percent of Exposed Population At 10\-4\ Risk or Higher 
for Bladder Cancer Incidence\1\ After Treatment \2\ (Community Water 
Consumption Data \3\)
Table X-3b. Percent of Exposed Population At 10\-4\ Risk or Higher 
for Bladder Cancer Incidence\1\ After Treatment \2\ (Total Water 
Consumption Data \3\)
Table X-4a. Mean Bladder Cancer Incidence Risks \1\ for U.S. 
Populations Exposed At or Above MCL Options, after Treatment \2\ 
(Community Water Consumption Data \3\)
Table X-4b. Mean Bladder Cancer Incidence Risks \1\ for U.S. 
Populations Exposed At or Above MCL Options, after Treatment \2\ 
(Total Water Consumption Data \3\)
Table X-5. Lifetime Avoided Medical Costs For Survivors (preliminary 
estimates, 1996 dollars \1\)
Table X-6. Mean Bladder Cancer Incidence Risks \1\ for U.S. 
Populations Exposed At or Above MCL Options, after Treatment \2\ 
(Composite of Tables X-5a and X-5b)
Table X-7. Estimated Costs and Benefits from Reducing Arsenic in 
Drinking Water ($millions, 1999)
Table XI-1. Estimated Costs and Benefits from Reducing Arsenic in 
Drinking Water (In 1999 $ millions)
Table XI-2. Exposure Factors Used in the NTNC Risk Assessment
Table XI-3. Composition of Non-Transient, Non-Community Water 
Systems (Percentage of Total NTNC Population Served by Sector)

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Table XI-4. Upper Bound School Children Risk Associated with Current 
Arsenic Exposure in NTNC Water Systems
Table XI-5. Non-Transient Non-Community Benefit Cost Analysis
Table XI-6. Sensitive Group Evaluation Lifetime Risks
Table XIII-1. Risk Reduction from Reducing Arsenic in Drinking Water
Table XIII-2. Mean Bladder Cancer Risks and Exposed Population
Table XIII-3. Estimated Costs and Benefits from Reducing Arsenic in 
Drinking Water (in 1999 $ millions)
Table XIII-4. Estimated Annualized National Costs of Reducing 
Arsenic Exposures (in 1999 $ millions)
Table XIII-5. Estimated Annual Costs per Household \1\ (in 1999 $)
Table XIII-6. Summary of the Total Annual National Costs of 
Compliance with the Proposed Arsenic Rule Across MCL Options (in 
1997 $ millions)
Table XIII-7. Estimates of the Annual Incremental Risk Reduction, 
Benefits, and Costs of Reducing Arsenic in Drinking Water 
($millions, 1999)
Table XIV-1. Profile of the Universe of Small Water Systems 
Regulated Under the Arsenic Rule
Table XIV-2. Average Annual Cost per CWS by Ownership
Table XIV-3. Average Compliance Costs per Household for CWSs 
Exceeding MCLs
Table XIV-4. Average Compliance Costs per Household for CWSs 
Exceeding MCLs as a Percent of Median Household Income
Table XIV-5. Hour Burden per Activity for Public Water Systems
Table XIV-6. Hour Burden per Activity for States and Tribes

I. Summary of Regulation

    EPA is proposing an arsenic regulation for community water systems, 
which are systems that provide piped water to at least fifteen service 
connections used by year-round residents or regularly serves at least 
twenty-five year-round residents. This proposal will require non-
transient, non-community water systems (NTNCWS) to monitor for arsenic 
and report exceedances of the MCL. The proposed health-based, non-
enforceable goal, or Maximum Contaminant Level Goal (MCLG), is zero, 
based on EPA's revised risk characterization.
    EPA evaluated the analytical capability and laboratory capacity, 
likelihood of water systems choosing treatment technologies for several 
sizes of systems based on source water properties, and the national 
occurrence of arsenic in water supplies to determine the proposed 
Maximum Contaminant Level (MCL). Furthermore, the Agency analyzed the 
quantifiable and nonquantifiable costs and health risk reduction 
benefits likely to occur at the treatment levels considered, and the 
effects on sensitive subpopulations. Based on the determination that 
the costs for the feasible MCL do not justify the benefits, EPA is 
proposing an MCL of 0.005 mg/L and requesting comment on 0.003 mg/L, 
0.010 mg/L, and 0.020 mg/L. The treatment technologies for large 
systems are primarily coagulation/filtration and lime softening, while 
EPA expects that small systems (serving less than 10,000 people) will 
be able to use ion exchange, activated alumina, reverse osmosis, 
nanofiltration, and electrodialysis reversal. The effective date will 
be five years after the final rule comes out for community water 
systems serving 10,000 people or less, and three years after 
promulgation for all other community water systems. EPA is proposing 
that States applying to adopt the revised arsenic MCL may use their 
most recently approved monitoring and waiver plans or note in their 
primacy application any revisions to those plans.
    The Agency is clarifying the procedure used for determining 
compliance after exceedances for inorganic, volatile organic, and 
synthetic organic contaminants in this proposal. Finally, EPA is 
proposing in this proposal that States will specify the time frame 
which new systems and systems using a new source of water have to 
demonstrate compliance with the MCL's including initial sampling 
frequencies and compliance periods for new systems and systems that use 
a new source of water for inorganic, volatile organic, and synthetic 
organic contaminants.

II. Background

A. What Is the Statutory Authority for the Arsenic Drinking Water 
Regulation?

    Section 1401 of the Safe Drinking Water Act (SDWA) requires a 
``primary drinking water regulation'' to specify a maximum contaminant 
level (MCL) if it is economically and technically feasible to measure 
the contaminant and include testing procedures to insure compliance 
with the MCL and proper operation and maintenance. In addition, section 
1401(1)(D)(i) requires EPA to establish the minimum quality of 
untreated, or raw, water taken into a public water system. A national 
primary drinking water regulation (NPDWR) that establishes an MCL also 
lists the technologies that are feasible to meet the MCL, but systems 
are not required to use the listed technologies (section 
1412(b)(3)(E)(i)). As a result of the 1996 amendments to SDWA, when 
issuing a NPDWR, EPA will also list affordable technologies for small 
systems serving 10,000 to 3301, 3300 to 501, and 500 to 25 that achieve 
compliance with the MCL or treatment technique. EPA can list modular 
(packaged) and point-of-entry and point-of-use treatment units for the 
three small system sizes, as long as the units are maintained by the 
public water system or its contractors. Home units must contain 
mechanical warnings to notify customers of problems (section 
1412(b)(4)(E)(ii)). In section 1412(b)(12)(A) of SDWA, as amended 
August 6, 1996, Congress directed EPA to propose a national primary 
drinking water regulation for arsenic by January 1, 2000 and issue the 
final regulation by January 1, 2001. At the same time, Congress 
directed EPA to develop a research plan by February 2, 1997 to reduce 
the uncertainty in assessing health risks from low levels of arsenic 
and conduct the research in consultation with the National Academy of 
Sciences, other Federal agencies, and interested public and private 
entities. The amendments allowed EPA to enter into cooperative 
agreements for research.
    Section 1412(a)(3) requires EPA to propose a maximum contaminant 
level goal (MCLG) simultaneously with the national primary drinking 
water regulation. The MCLG is defined in section1412(b)(4)(A) as ``the 
level at which no known or anticipated adverse effects on the health of 
persons occur and which allows an adequate margin of safety.'' Section 
1412(b)(4)(B) specifies that each national primary drinking water 
regulation will specify a maximum contaminant level (MCL) as close to 
the MCLG as is feasible, with two exceptions added in the 1996 
amendments. First, the Administrator may establish an MCL at a level 
other than the feasible level if the treatment to meet the feasible MCL 
would increase the risk from other contaminants or the technology would 
interfere with the treatment of other contaminants (section1412(b)(5)). 
Second, if benefits at the feasible level would not justify the costs, 
EPA may propose and promulgate an MCL ``that maximizes health risk 
reduction benefits at a cost that is justified by the benefits (section 
1412(b)(6)).''
    When proposing an MCL, EPA must publish, and seek public comment 
on, the health risk reduction and cost analyses (HRRCA) of each 
alternative maximum contaminant level considered (section 
1412(b)(3)(C)(i)). This includes the quantifiable and nonquantifiable 
benefits from reductions in health risk, including those from removing 
co-occurring contaminants (not counting benefits resulting from 
compliance with other proposed or final regulations), costs of 
compliance (not counting costs resulting from other regulations), any 
increased health risks (including those from co-occurring contaminants) 
that

[[Page 38893]]

may result from compliance, incremental costs and benefits of each 
alternative MCL considered, and the effects on sensitive subpopulations 
(e.g., infants, children, pregnant women, elderly, seriously ill, or 
other groups at greater risk). EPA must analyze the quality and extent 
of the information, the uncertainties in the analysis, and the degree 
and nature of the risk.
    The 1996 amendments also require EPA to base its action on the best 
available, peer-reviewed science and supporting studies and to present 
health effects information to the public in an understandable fashion. 
To meet the latter obligation, EPA must specify, among other things, 
the methodology used to reconcile inconsistencies in the scientific 
data for the final regulation (section 1412(b)(3)(B)(v)).
    Section 1451(a) allows EPA to delegate primary enforcement 
responsibility to federally recognized Indian Tribes, providing grant 
and contract assistance, using the procedures applied to States. 
Section 1413(a)(1) allows EPA to grant States primary enforcement 
responsibility for NPDWRs when EPA has determined that the State has 
adopted regulations that are no less stringent than EPA's. States must 
adopt comparable regulations within two years of EPA's promulgation of 
the final rule, unless a two-year extension is justified. State primacy 
also requires, among other things, adequate enforcement (including 
monitoring and inspections) and reporting. EPA must approve or deny 
State applications within 90 days of submission (section 1413(b)(2)). 
In some cases, a State submitting revisions to adopt a national primary 
drinking water regulation has enforcement authority for the new 
regulation while EPA action on the revision is pending (section 
1413(c)).

B. What Is Arsenic?

    Arsenic is an element that occurs naturally in rocks, soil, water, 
air, plants, and animals. Arsenic is a metalloid, which exhibits both 
metallic and nonmetallic chemical and physical properties. The primary 
valence states for arsenic are 0, -3, +3 and +5. Although arsenic is 
found in nature to a small extent in its elemental form (0 valence), it 
occurs most often as inorganic and organic compounds in either the As 
(III) (+3) or As (V) (+5) valence states. The trivalent forms of 
inorganic arsenic [As (III) (e.g., arsenite, 
H3AsO3)] and the pentavalent forms [As (V) (e.g., 
arsenate, H2AsO4-, 
HAsO42-)] are inorganic species which tend to be 
more prevalent in water than the organic arsenic species (Irgolic, 
1994; Clifford and Zhang, 1994). The dominant inorganic species present 
in water is largely a function of the pH and the oxidizing/reducing 
conditions which affects the need for pretreatment and removal effects. 
Arsenates are more likely to occur in aerobic surface waters and 
arsenites are more likely to occur in anaerobic ground waters.

C. What Are the Sources of Arsenic Exposure?

1. Natural Sources of Arsenic
    There are numerous natural sources as well as human activities that 
may introduce arsenic into food and drinking water. The primary natural 
sources include geologic formations (e.g., rocks, soil, and sedimentary 
deposits), geothermal activity, and volcanic activity. Arsenic and its 
compounds comprise 1.5-2% of the earth's crust (Welch, personal 
communication). While concentrations of arsenic in the earth's crust 
vary, the average concentrations are generally reported to range from 
1.5 to 5 mg/kg. Arsenic is a major constituent of many mineral species 
in igneous and sedimentary rocks. It is commonly present in the sulfide 
ores of metals including copper, lead, silver, and gold. There are over 
100 arsenic-containing minerals, including arsenic pyrites (e.g., 
FeAsS), realgar (AsS), lollingite (FeAs2, 
Fe2As3, Fe2As5), and 
orpiment (As2S3). Geothermal water can be a 
source of inorganic arsenic in surface water and ground water. Welch et 
al. (1988) identified fourteen areas in the Western United States where 
dissolved arsenic concentrations ranged from 80 to 15,000 g/L. 
In addition, natural emissions of arsenic are associated with forest 
fires and grass fires. Volcanic activity appears to be the largest 
natural source of arsenic emissions to the atmosphere (ATSDR, 1998). 
Arsenic compounds, both inorganic and organic, are also found in food.
2. Industrial Sources of Arsenic
    Major present and past sources of arsenic include wood 
preservatives, agricultural uses, industrial uses, mining and smelting. 
The human impact on arsenic levels in water depends on the level of 
human activity, the distance from the pollution sources, and the 
dispersion and fate of the arsenic that is released. The production of 
chromated copper arsenate (CCA), an inorganic arsenic compound and wood 
preservative, accounts for approximately 90% of the arsenic used 
annually by industry in the United States (USGS, 1998; USGS, 1999). CCA 
is used to pressure treat lumber, which is typically used for the 
construction of decks, fences, and other outdoor applications. In 
addition to wood preservatives, the other EPA-registered use of 
inorganic arsenic is for sealed ant bait. In the past, agricultural 
uses of arsenic included pesticides, herbicides, insecticides, 
defoliants, and soil sterilants. Inorganic arsenic pesticides are no 
longer used for agricultural purposes; the last agricultural 
application was voluntarily canceled in 1993 (58 FR 64579, US EPA, 
1993b).
    Organic forms of arsenic are constituents of some agricultural 
pesticides that are currently used in the U.S. Monosodium 
methanearsonate (MSMA) is the most widely applied organoarsenical 
pesticide, which is used to control broadleaf weeds and is applied to 
cotton (Jordan et al., 1997). Small amounts of disodium methanearsonate 
(DSMA, or cacodylic acid) are also applied to cotton fields as 
herbicides. The Food and Drug Administration regulates other organic 
arsenicals (e.g., roxarsone and arsanilic acid) used as feed additives 
for poultry and swine for increased rate of weight gain, improved feed 
efficiencies, improved pigmentation, and disease treatment and 
prevention. These additives undergo little or no metabolism before 
excretion (NAS, 1977; Moody and Williams, 1964; Aschbacher and Feil, 
1991).
    Arsenic and arsenic compounds (arsenicals) are used for a variety 
of industrial purposes, including: electrophotography, catalysts, 
pyrotechnics, antifouling paints, pharmaceutical substances, dye and 
soaps, ceramics, alloys (automotive solder and radiators), battery 
plates, optoelectronic devices, semiconductors, and light emitting 
diodes in digital watches (Azcue and Nriagu, 1994). In addition, 
burning of fossil fuels, combustion of wastes, mining and smelting, 
pulp and paper production, glass manufacturing, and cement 
manufacturing can result in emissions of arsenic to the environment (US 
EPA, 1998). Arsenic has been identified as a contaminant of concern at 
916 of the 1,467 National Priorities List (Superfund) hazardous waste 
sites (ATSDR, 1998).
3. Dietary Sources
    Because arsenic is naturally occurring, the entire population is 
exposed to low levels of arsenic through food, water, air, and contact 
with soil. The National Research Council report (NRC, 1999) described 
in sections III.C. and III.E.3. provides Food and Drug Administration 
(FDA) ``market basket'' data for total arsenic intake by age

[[Page 38894]]

group. NRC assumed that, for fish and seafood, inorganic arsenic is 10% 
of the total arsenic and that other food contains entirely inorganic 
arsenic. These assumptions are probably high and conservative for 
public health protection to avoid underestimating the contributions 
from food. Table 3-5 in the 1999 NRC report characterizes inorganic 
arsenic intake from food in the U.S. as being 1.3 g/day for 
infants under one year old, 4.4 g/day for 2-year olds, almost 
10 g/day for 25-30 year-old males, with a maximum of 12.5 
g/day for 60-65 year-old males (females had lower arsenic 
intake in every age group). MacIntosh et al. (1997) estimated that 785 
adults had a mean inorganic arsenic consumption of 10.22 g/
day, with a standard deviation of 6.54 g/day and a range of 
0.36-123.84 g/day based on semi-quantitative food surveys.
    Likewise, the 2 L/day assumption of adult drinking water intake 
used to develop the MCLG does not represent intake by the average 
person; rather it represents intake of a person in the 90th percentile. 
(See Section X.B.1.a. for a description of water consumption for the 
general population.)
4. Environmental Sources
    Internal exposure after skin contact with water or soil containing 
arsenic or inhalation of arsenic from air is believed to be low. 
Studies of inorganic arsenic absorption from skin from cadavers 
estimated 0.8% uptake from soil and 1.9% uptake from water over a 24-
hour period (Wester et al., 1993). EPA's arsenic health assessment 
document for the Clean Air Act (US EPA, 1984) cited respiratory arsenic 
as being about 0.12 g/day from a daily ventilation rate of 20 
m\3\ using a 1981 national average arsenic air concentration of 0.006 
g/m\3\. Assuming 30 percent absorption, the daily amount of 
arsenic from breathing would be 0.03 g, so air is a minor 
source of arsenic (50 FR 46936 at 46960; US EPA, 1985b). At this time, 
EPA is basing health risks on estimates of arsenic exposure from food 
and water. The Centers for Disease Control and Prevention (CDC) is 
initiating a study of arsenic intake from bathing. EPA requests comment 
on whether available data on skin absorption and inhalation indicate 
that these are significant exposure routes that should be considered in 
the risk assessment.

D. What is the Regulatory History for Arsenic?

    Regulation of arsenic has been the subject of scientific debate 
that has lasted for decades despite research and scientific review. The 
controversy has affected policy and regulatory decisions for arsenic in 
drinking water from low, environmental exposure.
1. Earliest U.S. Arsenic Drinking Water Standards
    In 1942 the U.S. Public Health Service first established an arsenic 
drinking water standard for interstate water carriers at 0.05 mg 
arsenic per liter (mg/L, or 50 g/L), as measured with a 
colorimetric method. The report did not cite any reason for choosing 
that level, but it defined ``safety of water supplies'' as ``the 
danger, if any, is so small that it cannot be discovered by available 
means of observation (US Public Health Service 1943).'' In 1946, the 
Surgeon General of the U.S. Public Health Service noted that the 
American Water Works Association had accepted the 1942 drinking water 
standards, including the arsenic standard (U.S. Public Health Service 
1946). In 1962 (U.S. Public Health Service 1962) the U.S. Public Health 
Service issued more stringent drinking water standards for arsenic of 
0.01 mg/L (10 g/L) for a water supply in 42 CFR 72.205(b)(1) 
and 0.05 mg/L in 42 CFR 72.205(b)(2) as grounds for rejection of a 
water supply, as measured by the current edition of Standard Methods 
for the Examination of Water and Wastewater per 42 CFR 72.207(a).
    The Safe Drinking Water Act of 1974 amended the Public Health 
Service Act and specified that EPA set primary and secondary drinking 
water standards. On December 24, 1975 (40 FR 59566 at 59570; US EPA, 
1975), EPA issued a National Interim Primary Drinking Water Regulation 
for arsenic in Sec. 141.23(b) of 0.05 mg/L (50 g/L), effective 
18 months later (Sec. 141.6). Commenters recommended an MCL of 100 
g/L, saying there were no observed adverse health effects (40 
FR 59566 at 59576; US EPA, 1975). EPA noted long-term chronic effects 
at 300-2,750 g/L, but observed no illnesses in a California 
study at 120 g/L. Drinking 2 liters of water a day containing 
arsenic at 50 g/L would provide approximately 10% of total 
ingested arsenic from food and water, estimated to be 900 g/
day. The section on arsenic noted that arsenic has been believed to be 
a carcinogen ``[s]ince the early nineteenth century  * *; however 
evidence from animal experiments and human experience has accumulated 
to strongly suggest that arsenicals do not produce cancer. One 
exception is a report from Taiwan * * *. The text goes on to note 
occupational skin and lung cancer from arsenic dust and skin cancer in 
England from drinking water with 12 mg/L. (US EPA, 1976 Appendix A).
2. EPA's 1980 Guidelines
    Scientific data at the time the 1980 Ambient Water Quality 
Guidelines were formulated did not support a safe or ``threshold'' 
concentration for carcinogens, so EPA's public health policy was

``that the recommended concentration for maximum protection of human 
health is zero. In addition, the Agency presented a range of 
concentrations corresponding to incremental cancer risks of 10-\7\ 
to 10-\5\ (one additional case of cancer in populations ranging from 
ten million to 100,000, respectively) * * * [that did not 
necessarily represent] an Agency judgement on an `acceptable' risk 
level (45 FR 79318 at 79323, US EPA, 1980).''

    In the November 28, 1980 Federal Register document, using its then 
current risk assessment approach (assumed toxicity increased as a 
natural logarithm linear function across species), EPA set the Clean 
Water Act surface water quality criterion for arsenic at 2.2 nanograms 
(ng/L) (0.0022 g/L) at an increased cancer risk of 10-\6\. The 
criterion was to prevent skin cancer in humans drinking contaminated 
water and eating aquatic organisms from those water bodies (45 FR 79318 
at 79326). The 1980 Federal Register notice indicated that drinking 
water standards consider a range of factors, including health effects, 
technological and economic feasibility of removal, and monitoring 
capability. On the other hand the Clean Water Act criteria of section 
304(a)(1) ``have no regulatory significance under the SDWA.'' The Clean 
Water Act section 304(a)(1) criteria are more similar to the health-
based goals of the recommended maximum contaminant levels (now referred 
to as MCLGs), than to MCLs; and differences in mandates ``may result in 
differences between the two numbers.'' (45 FR 79318 at 79320; US EPA, 
1980). In 1992, the Clean Water Act criterion was recalculated based on 
the updated cancer risk assessment in EPA's Integrated Risk Information 
System (IRIS) database, to a level of 0.018 g/L for arsenic at 
a 10-\6\ cancer risk (57 FR 60848; US EPA, 1992c).
3. Research and Regulatory Work
    The 1980 National Academy of Science (NAS) Volume III of ``Drinking 
Water and Health'' report encouraged EPA to research whether arsenic is 
essential for humans, as demonstrated in four studies of mammalian 
species. The 1983 NAS Volume V report projected that 0.05 mg/kg of 
total arsenic may be a desirable level for people, and 25 to 50 
g a day may be required (as cited in 50 FR 46936 at 46960; US 
EPA, 1985b).

[[Page 38895]]

    In 1983, EPA requested comment on whether the arsenic MCL should 
consider carcinogenicity, other health effects, and nutritional 
requirements, and whether MCLs are necessary for separate valence 
states (e.g., arsenite vs. arsenate) (48 FR 45502 at 45512; US EPA, 
1983). On November 13, 1985, EPA proposed (50 FR 46936; US EPA, 1985b) 
a recommended maximum contaminant level (RMCL), a non-enforceable 
health goal now known as an MCLG, of 50 g/L based on the 1983 
NAS conclusion that 50 g/L balanced toxicity and possible 
essentiality and provided ``a sufficient margin of safety'' (50 FR 
46936 at 46960). EPA also requested comment on alternate RMCLs of 100 
g/L based on noncarcinogenic effects (calculated from an 
animal study and an uncertainty factor of 1000) and 0 g/L 
based on carcinogenicity (50 FR 46936 at 46961). EPA chose not to base 
the proposed RMCL on the animal study because each dose group had only 
four Rhesus monkeys. Also, at that time, studies had ``not detected 
increased risks via drinking water in the USA'' (50 FR 46936 at 46960). 
The 1985 proposed drinking water regulation preamble noted the 1980 
excess cancer risk values derived from the ambient water quality 
criteria were based on skin cancer using the 1968 Tseng et al. study 
(50 FR 46936 at 46961).
    The June 19, 1986 amendments to the Safe Drinking Water Act (SDWA; 
Public Law 99-339) converted the 1975 interim arsenic standard to a 
National Primary Drinking Water Regulation (section 1412(a)(1)), 
subject to revision by 1989 (section 1412(b)(1)). Review of the arsenic 
risk assessment issues caused the Agency to miss the 1989 deadline for 
proposing a revised NPDWR. As a result of a citizen suit to enforce the 
deadline, EPA entered into a consent decree providing deadlines for 
issuing the arsenic rule.
    In 1988, EPA's Risk Assessment Forum issued the Special Report on 
Ingested Inorganic Arsenic: Skin Cancer; Nutritional Essentiality (EPA/
625/3-87/013), in part, to evaluate the validity of applying skin 
cancer data from Taiwanese studies (published in 1968 and 1977) in 
dose-response assessments in the U.S. As described in the report, the 
maximum likelihood estimate of risk ranged from 3  x  10-\5\ to 7  x  
10-\5\ for a 70-kilogram person consuming 2 liters of water per day 
contaminated with 1 g of arsenic per liter. Calculated at the 
50 g/L standard, the U.S. lifetime risk of skin cancer ranged 
from 1  x  10-\3\ to 3  x  10-\3\, which means one to three skin 
cancers would occur in a group of one thousand people drinking water 
containing arsenic at 50 g/L. Existing studies could not 
determine whether arsenic was an essential nutrient.
    After reviewing the scientific evidence for carcinogenicity, EPA's 
Science Advisory Board (US EPA, 1989a and b) stated in its August 1989 
and September 1989 reports that (1) the animal studies suggesting 
arsenic is an essential nutrient are not definitive; (2) the skin 
changes seen in hyperkeratosis may not always result in skin cancer; 
(3) the 1968 Taiwan data demonstrate that high doses of ingested 
arsenic can cause skin cancer; (4) the Taiwan study is inconclusive to 
determine cancer risk at levels ingested in the United States (U.S.); 
and (5) As (III) levels below 200-250 g per day may be 
detoxified. SAB recommended that EPA set the MCL using a non-linear 
dose-response (at some low dose, arsenic would not be toxic). The SAB 
report recommended that EPA revise the risk assessment based on dose of 
arsenic to target tissues (the concentration of arsenic that damages 
tissues, rather than the concentration in water) and consider 
detoxification.
    The SAB also reviewed EPA's April 12, 1991 Arsenic Research 
Recommendations (US EPA, 1991c). The final report provided SAB's 
recommendations (US EPA, 1992a) and ``identified research needed to 
resolve major uncertainties about inorganic arsenic cancer risk'' to 
evaluate if work could be done in three to five years. It noted that 
``important work can be done within the time available. Although the 
results from this work will not completely resolve any issue, * * * the 
results will likely significantly improve the Agency's ability to 
evaluate the risk. * * * through improved knowledge of arsenic 
metabolism and * * * as a carcinogen.'' The report reflected 
uncertainty as to whether or not EPA could obtain enough data to 
regulate arsenic using a non-linear model, which needed more 
information on how arsenic induces cancer. The group noted that it 
would take longer than five years to develop an animal model to help 
understand the toxicity of arsenic. SAB recommended four short-term 
studies: (a) Investigation of chromosome damage, arsenic metabolites, 
and the times cells are most susceptible to arsenic, (b) study of human 
liver capacity to add methyl groups to arsenic, (c) identifying the 
species in urine in several populations to look for evidence of 
saturation of methylation enzymes, and (d) comparing methylated arsenic 
excreted in the U.S., Taiwan, Mexico, and Argentina to consider the 
effect of nutritional or genetic differences on methylation capacity. 
However, if time were not a factor, SAB ranked developing an animal 
model of arsenic-induced cancer as the first priority.
    In 1993 SAB reviewed EPA's draft ``Drinking Water Criteria Document 
on Inorganic Arsenic (US EPA, 1993a).'' In 1995, SAB reviewed the 
analytical methods, occurrence estimate, treatment technologies, and 
approach for assigning costs in the regulatory impact analysis (US EPA, 
1995). Besides highlighting previous SAB reviews of 1989, 1992, and 
1994 on health effects, the 1995 report recommended changes to the 
practical quantitation limit approach, use of occurrence data, review 
of technologies, and support for the decision tree, with some 
reservations.
    EPA held internal workgroup meetings throughout 1994, addressing 
risk assessment, treatment, analytical methods, arsenic occurrence, 
exposure, costs, implementation issues, and regulatory options. EPA 
decided in early 1995 to defer the arsenic regulation in order to 
better characterize health effects and assess cost-effective removal 
technologies for small utilities.
    The 1996 amendments to SDWA included a new statutory deadline for 
the arsenic regulations, as discussed in section II.A.

E. EPA's Arsenic Research Plan

    EPA held a workshop in March 1994 entitled ``Workshop on Developing 
an Epidemiology Research Strategy for Arsenic in Drinking Water.'' The 
cover letter to the final report (US EPA, 1997b), dated April 14, 1997, 
notes that EPA has been using the recommendations to direct its 
research directions. The report listed ten projects and seventeen 
conclusions on exposure, endpoints, study design and statistical power, 
population selection, feasibility of conducting a study in the U.S., 
international studies, importance of developing biomarkers to measure 
health effects of arsenic, and animal studies.
    In 1995, the Water Industry Technical Action Fund (WITAF) ( funded 
by the American Water Works Association, National Association of Water 
Companies, Association of Metropolitan Water Agencies, National Rural 
Water Association, and National Water Resources Association), the AWWA 
Research Foundation, and the Association of California Water Agencies 
(ACWA) sponsored an Expert Workshop on Arsenic Research Needs in 
Ellicott City, MD, May 31-June 2, 1995. The final report (AWWA et al., 
1995) identified research projects in mechanisms, epidemiology, 
toxicology, and treatment. It identified ten high

[[Page 38896]]

priority projects which would need over $3 million to fund, eleven 
medium priority projects needing over $6 million, and ten low priority 
projects costing over $9 million, that totaled over $19 million in 
research needs.
    Congress recognized the importance of health effects research in 
regulating arsenic, as demonstrated by the 1996 statutory requirement 
to develop a research plan within 180 days ``in support of drinking 
water rulemaking to reduce the uncertainty in assessing health risks 
associated with exposure to low levels of arsenic * * * (section 
1412(b)(12)(A)(ii)). In the research plan EPA recognized that ``[t]he 
research needs are broader than those that EPA can address alone, and 
it is anticipated that other entities will be involved in conducting 
some of the needed research (US EPA, 1998a).'' (See section III.E.1. on 
industry-funded research and the arsenic research plan (at www.epa.gov/ORD/WebPubs/final/arsenic.pdf) for EPA-funded projects.) In December 
1996, EPA submitted its draft research plan for peer review by its 
Board of Scientific Counselors' (BOSC) Ad Hoc Committee, and the 
committee met in January 1997. The February 1998 Arsenic Research Plan 
addressed the June 1997 comments from BOSC.
    Major areas covered in the research plan included studies to:
     Improve our qualitative and quantitative assessment of the 
human toxicity of arsenic;
     Understand mechanisms of arsenic toxicity that may aid in 
extension of the observed human findings when extrapolation is 
required;
     Measure exposures of the US population to arsenic from 
various sources (particularly diet) to allow better definition of 
cumulative exposures to arsenic;
     Refine treatment technologies that may better remove 
arsenic from water supplies;
     Improve methods for analyzing and monitoring arsenic in 
drinking water.
    EPA also set priorities in the plan and identified projects that 
met the short term and long term criteria:
Short Term Criteria
    1. Will the research improve the scientific basis for risk 
assessments needed for proposing a revised arsenic MCL by January 1, 
2000?
    2. Will the research improve the scientific basis for risk 
management decisons needed for proposinig a revised arsenic MCL by 
January 1, 2000?
Long Term Criteria
    1. Will the research improve the scientific basis for risk 
assessment and risk management decisions needed to review and develop 
future MCLs beyond the year 2000?
    2. Is the research essential to improving our scientific 
understanding of the health risks of arsenic?
    The research plan included the following priority topics for 
research under the five major areas of investigation supporting 
drinking water rulemaking:

Exposure Analysis

     Arsenic speciation and preservation: Improvements in 
analytical methods to support water treatment decisions.
     Measurement of background exposures to arsenic in U.S. 
population, particularly inorganic arsenic intake in the U.S. diet.
     Development and evaluation of biomarkers (e.g., species of 
arsenic in urine) of exposures.
     Development of standard reference material for arsenic in 
water, food, urine, tissues.

Cancer Effects

     Further study of internal cancers associated with arsenic 
exposures.
     Dose response data on hyperkeratosis as a likely precursor 
to skin cancer.
     Research on factors influencing human susceptibility 
including age, genetic characteristics and dietary patterns.
     Metabolic and pharmacokinetic studies that can identify 
dose dependent metabolism.
     Mechanistic studies for arsenic-induced genotoxicity and 
carcinogenicity.

Noncancer Effects

     Development of human dose-response data for 
hyperkeratosis, cardiovascular disease, neurotoxicity and developmental 
effects.
     Development of additional health effects and hazard 
identification data on other non-cancer endpoints such as diabetes and 
hematologic effects.

Risk Management Research

     Identification of limitations of treatment technologies 
and impacts on water quality.
     Development of treatment technologies for small water 
systems.
     Development of data on cost and performance capabilities 
of various treatment options.
     Consideration of residuals management issues, including 
disposal options and costs.

Risk Assessment/Characterization

     Development of risk characterizations to provide interim 
support to States and local communities.
     Development of predictive tools and statistical models for 
assessing bioavailability, interactions and dose-response as better 
mass balance data become available.
     Comprehensive assessment of exposure levels and 
incorporation of data into risk estimates for better characterization 
of actual risks associated with arsenic exposure.
     Comprehensive assessment of arsenic mode of action provide 
a greater understanding of biological mechanisms and factors that may 
impact the shape of a dose response curve.
     Comprehensive assessment of non-cancer risks and 
consideration of appropriate modeling tools for quantitative estimation 
of non-cancer risks.
     Comprehensive assessment of human dose-response data for 
hyperkeratosis, cardiovascular disease, neurotoxicity and developmental 
effects.

III. Toxic Forms and Health Effects of Arsenic

A. What Are the toxic Forms of Arsenic?

    Arsenic exists in several forms which vary in toxicity and 
occurrence. Accordingly, for this proposed regulation, it is important 
to consider those forms that can exert toxic effects and to which 
people may be exposed. For example, the metallic form of arsenic (0 
valence) is not absorbed from the stomach and intestines and does not 
exert adverse effects. On the other hand, a volatile compound such as 
arsine (AsH3) is toxic, but is not present in water or food. 
Moreover, the primary organic forms (arsenobetaine and arsenocholine) 
found in fish and shellfish seem to have little or no toxicity 
(Sabbioni et al., 1991). Arsenobetaine quickly passes out of the body 
in urine without being metabolized to other compounds (Vahter, 1994). 
Arsenite (+3) and arsenate (+5) are the most prevalent toxic forms of 
inorganic arsenic that are found in drinking water. However, recovery 
of identified arsenic species in vegetables, grains and oils has been 
limited and difficult, so little is known about types of species in 
these foods (NRC, 1999).
    In animals and humans, inorganic pentavalent arsenic is converted 
to trivalent arsenic that can be methylated (i.e., chemically bonded to 
a methyl group, which is a carbon atom linked to

[[Page 38897]]

three hydrogen atoms) to mono-methyl arsenic (MMA) and di-methyl 
arsinic acid (DMA), which are organic arsenicals. The primary route of 
excretion for arsenic metabolites is in the urine. Studies indicate 
that the organic arsenicals MMA and DMA were hundreds of times less 
likely to produce genetic changes in animal cells than inorganic 
arsenicals. Moreover, many studies reported organic arsenicals to be 
less reactive in tissues, to kill less cells, and to be more easily 
excreted in urine (NRC, 1999).

B. What Are the Effects of Acute Toxicity?

    Inorganic arsenic can exert toxic effects after acute (short-term) 
or chronic (long-term) exposure. From human acute poisoning incidents, 
the LD50 of arsenic has been estimated to range from 1 to 4 
mg/kg (Vallee et al., 1960, Winship, 1984). This dose would correspond 
to a lethal dose range of 70 to 280 mg for 50% of adults weighing 70 
kg. At nonlethal, but high acute doses, inorganic arsenic can cause 
gastroenterological effects, shock, neuritis (continuous pain) and 
vascular effects in humans (Buchanan, 1962). Such incidents usually 
occur after accidental exposures. However, sometimes high dose acute 
exposures may be self-administered. For example, inorganic arsenic is a 
component of some herbal medicines and adverse effects have been 
reported after use. In one report of 74 cases (Tay and Seah, 1975), the 
primary signs were skin lesions (92%), neurological (i.e., nerve) 
involvement (51%), and gastroenterological, hematological (i.e., blood) 
and renal (i.e., kidney) effects (19 to 23%). Although acute or short-
term exposures to high doses of inorganic arsenic can cause adverse 
effects, such exposures do not occur from public water supplies in the 
U.S. at the current MCL of 50 g/L. EPA's proposed drinking 
water regulation addresses the long-term, chronic effects of exposure 
to low concentrations of inorganic arsenic in drinking water.

C. What Cancers Are Associated With Arsenic?

    Inorganic arsenic is a multi-site human carcinogen by the drinking 
water route. Asian, Mexican and South American populations with 
exposures to arsenic in drinking water generally at or above several 
hundred micrograms per liter are reported to have increased risks of 
skin, bladder, and lung cancer. The current evidence also suggests that 
the risks of liver and kidney cancer may also be increased following 
exposures to inorganic forms of arsenic. The weight of evidence for 
ingested arsenic as a causal factor of carcinogenicity is much greater 
now than a decade ago, and the types of cancer occurring as a result of 
ingesting inorganic arsenic have even greater health implications for 
U.S. and other populations than the occurrence of skin cancer alone. 
(Until the late 1980s skin cancer had been the cancer classically 
associated with arsenic in drinking water.) Epidemiologic studies 
(e.g., of people) provide direct data on arsenic risks from drinking 
water at exposure levels much closer to those of regulatory concern 
than environmental risk assessments based on animal toxicity studies.
1. Skin Cancer
    Early reports linking inorganic arsenic contamination of drinking 
water to skin cancer came from Argentina (Neubauer, 1947, reviewing 
studies published as early as 1925) and Poland (Geyer, 1898, as 
reported in Tseng et al., 1968). However, the first studies that 
observed dose-dependent effects of arsenic associated with skin cancer 
came from Taiwan (Tseng et al., 1968; Tseng, 1977). These studies 
focused EPA's attention on the health effects of ingested arsenic. 
Physicians physically examined over 40,000 residents from 37 villages 
and 7500 residents exposed to 0.017 mg/L arsenic ( reference group). 
The study population was divided into three groups based on exposure to 
inorganic arsenic (0 to 0.29, 0.30 to 0.59 and 0.60 mg of 
inorganic As/Liter) measured at the village level. A dose-and age-
related increase of arsenic-induced skin cancer among the villagers was 
noted. No skin cancers were observed in the low arsenic reference 
areas. The 1999 NRC report noted that the ``primary limitation of this 
study * * * was the lack of detail'' reported, such as grouping 
individuals into ``broad exposure groups'' (rather than grouping into 
37 village exposures). This limits the usefulness of these studies. 
However, these Tseng reports and other corroborating studies such as 
those by Albores et al. (1979) and Cebrian et al. (1983) on drinking 
water exposure and exposures to inorganic arsenic in medicines (Cuzick 
et al., 1982) and in pesticides (Roth, 1956) led the EPA, using skin 
cancer as the endpoint, to classify inorganic arsenic as a human 
carcinogen (Group A) by the oral route (US EPA, 1984).
2. Internal Cancers
    Exposure to inorganic arsenic in drinking water has also been 
associated with the development of internal cancers. ``No human studies 
of sufficient statistical power or scope have examined whether 
consumption of arsenic in drinking water at the current MCL results in 
an increased incidence of cancer or noncancer effects (NRC, 1999, pg. 
7).''
    Chen et al. (1985) used standardized mortality ratios (SMRs) to 
evaluate the association between ingested arsenic and cancer risk in 
Taiwan. (SMRs, ratios of observed to expected deaths from specific 
causes, are standardized to adjust for differences in the age 
distributions of the exposed and reference populations.) The authors 
found statistically significant increased risks of mortality for 
bladder, kidney, lung, liver and colon cancers. A subsequent mortality 
study in the same area of Taiwan found significant dose-response 
relationships for deaths from bladder, kidney, skin, and lung cancers 
in both sexes and from liver and prostate cancer for males. They also 
found increases in peripheral and cardiovascular diseases but not in 
cerebrovascular accidents (Wu et al., 1989). There are several 
corroborating reports of the increased risk of cancers of internal 
organs from ingested arsenic including two from two South American 
countries. In Argentina, significantly increased risks of death from 
bladder, lung and kidney cancer were reported (Hopenhayn-Rich et al., 
1996; 1998). In a population of approximately 400,000 in northern 
Chile, Smith et al. (1998) found significantly increased risks of 
bladder and lung cancer mortality.
    There have only been a few studies of inorganic arsenic exposure 
via drinking water in the U.S., and most have not considered cancer as 
an endpoint. People have written EPA asking that the new MCL be set 
considering that these U.S. studies have not seen increases in cancers 
at the low levels of arsenic exposure in U.S. drinking water. 
Optimally, low-exposure arsenic studies involve long-term residency 
(20-40 years with known drinking water arsenic exposure), access to 
health records, populations large enough to detect statistically 
significant increases in cancers and other health endpoints, and 
limited use of multiple sources of water (bottled, filtered, beverages, 
food prepared outside the home).
    Recently, Lewis et al. (1999) conducted a mortality study of a 
population in Utah whose drinking water contained relatively low 
concentrations of arsenic (averaged 18-191 g/L). They reported 
no significant increase in bladder or lung mortality. They did report a 
statistically significant dose-response for an increased risk of 
prostate cancer mortality. Smoking is an established risk factor for 
bladder and lung cancer, and inorganic arsenic

[[Page 38898]]

behaves as a comutagen even though it is not mutagenic alone (NRC, 
1999, pg. 200). It is possible that inorganic arsenic potentiates other 
risk factors for these cancers. This potential role is consistent with 
the NRC, 1999 view that arsenic's mode of action may be to interfere 
with cell ``housekeeping'' functions that normally repair genetic 
damage and ensure that damaged cells die (programmed cell death) rather 
than reproduce (see section III.D.2. below).

D. What Non-Cancer Effects Are Associated With Arsenic?

    A large number of adverse noncarcinogenic effects have been 
reported in humans after exposure to drinking water highly contaminated 
with inorganic arsenic. The earliest and most prominent changes are in 
the skin, e.g., hyperpigmentation and keratoses (calus-like growths). 
Other effects that have been reported include alterations in 
gastrointestinal, cardiovascular, hematological (e.g., anemia), 
pulmonary, neurological, immunological and reproductive/developmental 
function (ATSDR, 1998).
    The most common symptoms of inorganic arsenic exposure appear on 
the skin and occurr after 5-15 years of exposure equivalent to 700 
g/day for a 70 kg adult, or within 6 months to 3 years at 
exposures equivalent to 2,800 g/day for a 70 kg adult (pg. 131 
NRC, 1999). They include alterations in pigmentation and the 
development of keratoses which are localized primarily on the palms of 
the hands, the soles of the feet and the torso. The presence of 
hyperpigmentation and keratoses on parts of the body not exposed to the 
sun is characteristic of arsenic exposure (Yeh, 1973, Tseng, 1977). The 
same alterations have been reported in patients treated with Fowler's 
solution (1% potassium arsenite; Cuzick et al., 1982), used for asthma, 
psoriasis, rheumatic fever, leukemia, fever, pain, and as a tonic (WHO 
1981 and NRC 1999).
    Chronic exposure to inorganic arsenic is often associated with 
alterations in gastroenterological (GI) function. For example, 
noncirrhotic hypertension is a relatively specific, but not commonly 
found manifestation in inorganic arsenic-exposed individuals and may 
not become a clinical observation until the patient demonstrates GI 
bleeding (Morris et al., 1974; Nevens et al., 1990). Physical 
examination may reveal spleen and liver enlargement, and 
histopathological examination of tissue specimens may demonstrate 
periportal fibrosis (Morris et al., 1974; Nevens et al., 1990; Guha 
Mazumder et al., 1997). There have been a few reports of cirrhosis 
after inorganic arsenic exposure, but the authors of these studies did 
not determine the subjects' alcohol consumption (NRC 1999).
    Development of peripheral vascular disease (hardening of the 
arteries to the arms and legs, that can cause pain, numbness, tingling, 
infection, gangrene, and clots) after inorganic arsenic exposure has 
also been reported. In Taiwan, blackfoot disease (BFD, a severe 
peripheral vascular insufficiency which may result in gangrene of the 
feet and other extremities) has been the most severe manifestation of 
this effect. Tseng (1977) reported over 1,000 cases of BFD in the 
arsenic study areas of Taiwan. Less severe cases of peripheral vascular 
disease have been described in Chile (Zaldivar et al., 1974) and Mexico 
(Cebrian, 1987). In a Utah study, increased SMRs for hypertensive heart 
disease were noted in both males and females after exposure to 
inorganic arsenic-contaminated drinking water (Lewis et al., 1999). 
These reports link exposure to inorganic arsenic effects on the 
cardiovascular system.
    Studies in Taiwan (Lai et al., 1994) and Bangladesh (Rahman et al., 
1998) found an increased risk of diabetes among people consuming 
arsenic-contaminated water. Two Swedish studies found an increased risk 
of mortality from diabetes among those occupationally exposed to 
arsenic (Rahman and Axelson, 1995; Rahman et al., 1998).
    Although peripheral neuropathy (numbness, muscle weakness, tremors, 
ATSDR 1998) may be present after exposure to short-term, high doses of 
inorganic arsenic (Buchanan, 1962; Tay and Seah, 1975), there are no 
studies that definitely document this effect after exposure to levels 
of less than levels (50 g/L) of inorganic arsenic in drinking 
water. Hindmarsh et al. (1977) and Southwick et al. (1983) have 
reported limited evidence of peripheral neuropathy in Canada and the 
U.S., respectively, but it was not reported in studies from Taiwan, 
Argentina or Chile (Hotta, 1989, as cited by NRC 1999).
    There have been a few, scattered reports in the literature that 
inorganic arsenic can affect reproduction and development in humans 
(Borzysonyi et al., 1992; Desi et al., 1992; Tabacova et al., 1994). 
After reviewing the available literature on arsenic and reproductive 
effects, the National Research Council panel (NRC 1999) wrote that 
``nothing conclusive can be stated from these studies.''
    Based on the studies mentioned in this section, it is evident that 
inorganic arsenic contamination of drinking water can cause dermal and 
internal cancers, affect the GI system, alter cardiovascular function, 
and increase risk of diabetes, based on studies of people exposed to 
drinking water well above the current arsenic MCL. EPA's MCL is chosen 
to be protective of the general population within an acceptable risk 
range, not at levels at which adverse health effects are routinely seen 
(see section III.F.7. on risk considerations).

E. What Are the Recent Developments in Health Effects Research?

1. Funding of Health Effects Research
    As mentioned earlier in section II.A., Congress recognized that we 
needed more research to determine the health effects at low levels of 
arsenic (below the observed health effects and below 50 g/L). 
On December 6, 1996, EPA issued a Federal Register notice (61 FR 64739; 
US EPA, 1996e) asking for public comment on four arsenic health 
research topics to fund research projects with $2 million from EPA 
appropriations and $1 million in funds raised by water industry groups 
(US EPA, 1996d). In addition, the Office of Research and Development's 
(ORD's) Board of Scientific Counselors (BOSC) peer reviewed the draft 
research topics and the arsenic research plan. In the fall of 1997, EPA 
and the industry partners funded their respective choices for arsenic 
research, after having the applications peer reviewed. EPA issued three 
grants for the following research: Dose Response of Skin Keratoses and 
Hyper-Pigmentation, Arsenic Glutathione Interactions and Skin Cancer, 
and Cellular Redox Status. The water industry groups awarded two 
contracts, studying Contribution of Arsenic From Dietary Sources and 
Tumor Studies in Mice.
2. Expert Panel on Arsenic Carcinogenicity
    As part of the Integrated Risk Information System (IRIS) update 
effort, EPA sponsored an ``Expert Panel on Arsenic Carcinogenicity: 
Review and Workshop'' in May 1997 (US EPA, 1997d). The panel evaluated 
existing data to comment on arsenic's carcinogenic mode of action and 
the effect on dose-response extrapolations. The panel noted that 
arsenic compounds have not formed DNA adducts (i.e., bound to DNA) nor 
caused point mutations. Trivalent inorganic forms inhibit enzymes, but 
arsenite and arsenate do not affect DNA replication. The panel 
discussed several modes of action, concluding that arsenic indirectly 
affects DNA, inducing chromosomal changes. The panel thought that 
arsenic-induced

[[Page 38899]]

chromosomal abnormalities could possibly come from errors in DNA repair 
and replication that affect gene expression; that arsenic may increase 
DNA hypermethylation and oxidative stress; that arsenic may affect cell 
proliferation (cell death appears to be nonlinear); and that arsenic 
may act as a co-carcinogen. Arsenite causes cell transformation but not 
mutation of cells in culture. It also induces gene amplification 
(multiple copies of DNA sequences) in a way which suggests interference 
with DNA repair or cell control instead of direct DNA damage. The panel 
noted that all identified modes of action support a nonlinear dose-
response curve, that few data supports any one mode as most important, 
and that more than one mode of action may be operating. At low doses 
the slope of the dose response would decrease, and at very low doses 
``might effectively be linear but with a very shallow slope, probably 
indistinguishable from a threshold.''
    In terms of implications for the risk assessment, the panel noted 
that risk per unit dose estimates from human studies can be biased 
either way. For the Taiwanese study, the ``* * * biases associated with 
the use of average doses and with the attribution of all increased risk 
to arsenic would both lead to an overestimation of risk (US EPA, 1997d, 
page 31).'' While health effects are most likely observed in people 
getting high doses, the effects are assigned to the average dose of the 
exposure group. Thus, risk per unit dose estimated from the average 
doses would lead to an overestimation of risk (US EPA, 1997d, page 31).
3. NAS Review of EPA's Risk Assessment
    In 1997, at EPA's request, the National Academy of Sciences' (NAS) 
Subcommittee on Arsenic of the Committee on Toxicology of the National 
Research Council (NRC) met. Their charge was to review EPA's 
assessments of arsenic. The NAS/NRC Subcommittee finished their work in 
March 1999 (The report can be viewed from the National Academy Press 
website: www.nap.edu/books/0309063337/html/index.html). The detailed 
discussion of their work is in section III.F. In general, the NRC 
report confirms and extends concerns about human carcinogenicity of 
drinking water containing arsenic and offers perspective on dose-
response issues and needed research. For the decisions in this 
regulation, the EPA has relied upon the NRC report as presenting the 
best available, peer reviewed science as of its completion and has 
augmented it with more recently published, peer reviewed information. 
Further work on the risk assessment will also be done before the final 
rule is issued to analyze the risks of internal cancers. The NRC 
provided risk numbers for bladder cancer using the Agency's approach. 
The NRC report noted that ``some studies have shown that excess lung 
cancer deaths attributed to arsenic are 2-5 fold greater than the 
excess bladder cancer deaths. * * * (NRC, 1999, pg. 8).'' The NRC 
recommended that EPA analyze risks of internal cancers both separately 
and combined. Peer-reviewed quantitative analysis of lung tumor risk is 
expected to be available for consideration in the final rulemaking. 
Meanwhile, this proposal, in a ``what if'' analysis (discussed in 
section X.B), estimates the potential monetary benefits that would 
result if the lung cancer and bladder cancer risks were the same, which 
would be the case if the excess lung cancer deaths actually were 2- to 
5-fold greater than the excess bladder cancer deaths.
4. May 1999 Utah Mortality Study
    EPA scientists conducted an epidemiological study of 4,058 Mormons 
exposed to arsenic in drinking water in seven communities in Millard 
County, Utah (Lewis et al., 1999). The 151 samples from their public 
and private drinking water sources had arsenic concentrations ranging 
from 4 to 620 g/L with seven mean (arithmetic average) 
community exposure concentrations of 18 to 191 g/L and all 
seven community exposure medians (mid-point of arsenic values) 200 
g/L. Observed causes of death in the study group (numbering 
2,203) were compared to those expected from the same causes based upon 
death rates for the general white male and female population of Utah. 
Several factors suggest that the study population may not be 
representative of the rest of the United States. The Mormon church, the 
predominant religion in Utah, prohibits smoking and consumption of 
alcohol and caffeine. Utah had the lowest statewide smoking rates in 
the U.S. from 1984 to 1996, ranging from 13 to 17%. Mormon men had 
about half the cancers related to smoking (mouth, larynx, lung, 
esophagus, and bladder cancers) as the U.S. male population from 1971 
to 1985 (Lyon et al., 1994). The Utah study population was relatively 
small (4,000 persons) and primarily English, Scottish, and 
Scandinavian in ethnic background.
    While the study population males had a significantly higher risk of 
prostate cancer mortality, females had no significantexcess risk of 
cancer mortality at any site. Millard County subjects had higher 
mortality from kidney cancer, but this was not statistically 
significant. Both males and females in the study group had less risk of 
bladder, digestive system and lung cancer mortality than the general 
Utah population. The Mormon females had lower death rates from breast 
and female genital cancers than the State rate. These decreased death 
rates were not statistically significant.
    Although deaths due to hypertensive heart disease were roughly 
twice as high as expected in both sexes, increases in death did not 
relate to increases in dose, calculated as the years of exposure times 
the median arsenic concentration. The Utah data indicate that heart 
disease should be considered in the evaluation of potential benefits of 
U.S. regulation. Vascular effects have also been reported as an effect 
of arsenic exposure in studies in the U.S. (Engel et al. 1994), Taiwan 
(Wu et al., 1989) and Chile (Borgono et al., 1977). The overall 
evidence indicating an association of various vascular diseases with 
arsenic exposure supports consideration of this endpoint in evaluation 
of potential noncancer health benefits of arsenic exposure reduction.
5. 1999 Review of Health Effects
    Tsai et al. (1999) estimated standardized mortality ratios (SMR's) 
for 23 cancer and non-cancer causes of death in women and 27 causes of 
death in men in an area of Taiwan with elevated arsenic exposures 
(Tsai, et al., 1999). The SMRs in this study are an expression of the 
ratio between deaths that were observed in an area with elevated 
arsenic levels and those that were expected to occur, compared to both 
the mortality of populations in nearby areas without elevated arsenic 
levels and to the national population. Drinking water (250-1,140 
g/L) and soil (5.3-11.2 mg/kg) in the Tsai (1999) population 
study had high arsenic content. There are, of course, possible 
differences between the population and health care in Taiwan and the 
United States; and arsenic levels in the U.S. are not generally as high 
as they were in the study area of Taiwan. However, the study gives an 
indication of the types of health effects that may be associated with 
arsenic exposure via drinking water. The study reports a high mortality 
rate (SMR > 3) for both sexes from bladder, kidney, skin, lung, and 
nasal cavity cancers and for vascular disease. Females also had high 
mortalities for laryngeal cancer.
    The SMRs calculated by Tsai (1999) used the single cause of death 
noted on the death certificates. Many chronic

[[Page 38900]]

diseases, including some cancers, are not generally fatal. 
Consequently, the impact indicated by the SMR in this study may 
underestimate the total impact of these diseases. The causes of death 
reported in this study are consistent with what is known about the 
adverse effects of arsenic. Tsai et al. (1999) identified ``bronchitis, 
liver cirrhosis, nephropathy, intestinal cancer, rectal cancer, 
laryngeal cancer, and cerebrovascular disease'' as possibly ``related 
to chronic arsenic exposure via drinking water,'' which had not been 
reported before. In addition, people in the study area were observed to 
have nasal cavity and larynx cancers not caused by occupational 
exposure to inhaled arsenic.
6. Study of Bladder and Kidney Cancer in Finland
    Kurttio et al. (1999) conducted a case-cohort design study of 61 
bladder and 49 kidney cancer cases and 275 controls to evaluate the 
risk of these diseases with respect to arsenic drinking water 
concentrations. In this study the median exposure was 0.1 g/L, 
the maximum reported was 64 g/L, and 1% of the exposure was 
greater than 10 g/L. The authors reported that very low 
concentrations of arsenic in drinking water were significantly 
associated with being a case of bladder cancer when exposure occurred 
2-9 years prior to diagnosis. Arsenic exposure occurring greater than 
10 years prior to diagnosis was not associated with bladder cancer 
risk. Arsenic was not associated with kidney cancer risk even after 
consideration of a latency period.

F. What Did the National Academy of Sciences/National Research Council 
Report?

1. The National Research Council and Its Charge
    Due to controversy surrounding the risk assessment of inorganic 
arsenic, EPA asked the National Research Council (NRC) to do the 
following: (1) Review EPA's characterization of potential human health 
risks from ingestion of inorganic arsenic in drinking water; (2) review 
the available data on the carcinogenic and noncarcinogenic effects of 
inorganic arsenic; (3) review the data on the metabolism, kinetics and 
mechanism(s)/mode(s) of action of inorganic arsenic; and (4) identify 
research needs to fill data gaps. To accomplish this task, NRC convened 
a panel of scientific experts with backgrounds in chemistry, 
toxicology, genetics, epidemiology, nutrition, medicine, statistics and 
risk assessment. In addition to the general expertise of the panel 
members, many had conducted research on inorganic arsenic. NRC 
identified the thirteen scientists with ``diverse perspectives and 
technical expertise'' that peer reviewed the draft report. The report 
noted that ``EPA did not request, nor did the subcommittee endeavor to 
provide, a formal risk assessment for arsenic in drinking water (NRC, 
1999).''
2. Exposure
    Arsenic is naturally occurring and ubiquitously distributed in the 
earth's surface. Because of this, the general population is exposed to 
low levels of arsenic through the food supply. The NRC report provides 
FDA market basket data for inorganic arsenic intake by age group which, 
along with similar data for water intake, will permit communication of 
total exposure estimates of the general population by age group. The 
assumption is made in the FDA data that, for fish and seafood, 
inorganic arsenic is 10% of total arsenic. This 10% assumption is 
acknowledged to be conservative and has been adopted for public health 
protection so as not to underestimate the contribution from fish and 
seafood. Likewise, the 2 L/day assumption of adult drinking water 
intake does not represent intake by the average person; rather it 
represents intake of a person in the 90th percentile.
3. Essentiality
    The NRC report examined the question of essentiality of arsenic in 
the human diet. It found no information on essentiality in humans and 
only data in experimental animals suggesting growth promotion 
(arsenicals are fed to livestock for this reason). Inorganic arsenic 
has not been found to be essential for human well-being or involved in 
any required biochemical pathway. Given this and the fact that arsenic 
occurs naturally in food, consideration of essentiality is not 
necessary for public health decisions about water.
4. Metabolism and Disposition
    Data from humans show that inorganic arsenic is readily absorbed 
and transported through the body. It has a half-life in the body of 
approximately four days and is primarily excreted in the urine. If a 
human is exposed to the inorganic arsenate form (+5 valence), the 
arsenite will be reduced to arsenite (+3). Some of the arsenite will be 
sequentially methylated to form monomethylarsonic acid (MMA) and 
dimethylarsinic acid (DMA). This methylation process decreases acute 
toxicity and facilitates excretion from the body. Individuals and 
populations vary in their metabolism of arsenic. Such variations may be 
due to genetic differences, species and dose of inorganic arsenic 
ingested, nutrition, disease and possibly other factors. Whether these 
methylated products (MMA and DMA) play a role in the development of 
cancer and noncancer endpoints is unknown at the present time (NRC, 
1999). The NRC report recommended that experiments be conducted on the 
factors affecting interspecies differences in inorganic arsenic 
toxicity including use of human tissue when available.
5. Human Health Effects and Variations in Sensitivity
    The NRC panel concluded that there is sufficient evidence that 
chronic ingestion of inorganic arsenic causes bladder, lung and skin 
cancers and adverse noncancer effects on the cardiovascular systems, 
mainly from studies exposed to ``several hundred micrograms per liter. 
Few data address the degree of cancer risk at lower concentrations of 
ingested arsenic (NRC, 1999, pg. 130).'' The Utah study (Lewis et al., 
1999), published after the NRC report, indicates that cardiovascular 
effects can occur at lower exposures than those seen in the studies 
available for the NRC report. At the present time, the NRC report 
indicates that there is insufficient evidence to judge whether 
inorganic arsenic can affect reproduction or development in humans. 
However, inorganic arsenic can pass through the placenta (Concha et 
al., 1998), and developmental toxicity needs investigation. In animal 
studies, intraperitoneal (injection into the abdominal cavity) 
administration of inorganic arsenic can cause malformations, and oral 
dosing has been reported to alter fetal growth and viability. The NRC 
report recommended additional studies to characterize the dose-response 
curve for inorganic arsenic-induced cancer and noncancer health 
endpoints. They also stated that the reported beneficial effects of 
inorganic arsenic in animals should be carefully monitored. In 
addition, the potential effects of inorganic arsenic on human 
reproduction should be investigated.
    There are many factors (genetics, diet, metabolism, health and sex) 
that may affect a human's response to inorganic arsenic exposure. For 
example, reduction in methylation of inorganic arsenic methylation can 
cause humans to retain more arsenic in their tissues. The retention of 
a greater arsenic load could place a person at a greater risk. The NRC 
report (1999) recommended that various factors that have the ability

[[Page 38901]]

to alter a human's response to inorganic arsenic exposure be carefully 
examined. Specifically, these studies should focus on the extent of 
human variability with respect to metabolism, tissue deposition and 
excretion under different environmental conditions.
    Humans are variable in their metabolic processing of inorganic 
arsenic, and internal dose will vary from person to person because of 
this as well as because of diet, nutritional status, lifestyle, and 
health status. Human variability also exists in response 
characteristics (susceptibility). The full quantitative extent of this 
variability is not known. For instance, men are more susceptible than 
women to bladder cancer throughout the world even though bladder cancer 
rates vary from region to region. We do not know whether arsenic may 
have a greater effect at different ages (e.g., infants v.s. adults).
6. Modes of Action
    Knowledge of a ``mode of action'' means that data are available to 
describe the key events at the cellular and/or subcellular level that 
lead to the development of the cancer or noncancer endpoint. A number 
of potential modes of carcinogenic action have been proposed for 
arsenic, with varying degrees of supporting data. The key events in the 
cancer process caused by arsenic exposure are not known. Nevertheless, 
the data are sufficient to support the conclusion of the NRC report and 
the EPA 1997 expert panel workshop report that: ``Arsenic exposure 
induces chromosomal abnormalities without direct reaction with DNA (US 
EPA, 1997d).''
    There is strong evidence against a mode of action for inorganic 
arsenic involving direct reaction with DNA. One of the hallmarks of 
direct DNA reactivity is multi-species carcinogenic activity. For 
arsenic, long-term bioassays for carcinogenic activity in rats, mice, 
dogs, and monkeys have been uniformly negative (Furst, 1983). The kinds 
of genetic alterations seen in both in vivo and in vitro studies of 
arsenic effects are at the level of loss and rearrangement of 
chromosomes; these are results of errors of ``cellular housekeeping'' 
either in DNA repair or in chromosome replication. The NRC and EPA 
expert panel (US EPA, 1997d) reports examined several lines of evidence 
for various modes of action that might be operative. These included 
changes in DNA methylation patterns that could change gene expression 
and repair, oxidative stress, potentiation of effects of mutations 
caused by other agents, cell proliferative effects, and interference 
with normal DNA repair processes. Further examination in both of these 
reports of dose-response shapes associated with these effects led to 
the conclusion that they involve processes that have either thresholds 
of dose at which there would be no response or sublinearity of the dose 
response relationship (response decreasing disproportionately as dose 
decreases).
    The NRC report concluded: ``For arsenic carcinogenicity, the mode 
of action has not been established, but the several modes of action 
that are considered plausible (namely, indirect mechanisms of 
mutagenicity) would lead to a sublinear dose-response curve at some 
point below the point at which a significant increase in tumors is 
observed. * * * However, because a specific mode (or modes) of action 
has not yet been identified, it is prudent not to rule out the 
possibility of a linear response.''
    The NRC report noted that in certain in vitro studies of human and 
animal cells, genotoxic effects have been shown to occur at 
submicromolar concentrations of arsenite that are similar to 
concentrations found in urine of humans ingesting water at the current 
MCL. This emphasizes the potentially low margin of exposure (health 
effects observed at concentrations eight times above the MCL) for 
arsenic in water at the current MCL.
    For noncancer effects, inhibition of cellular respiration in 
mitochondria by arsenic may be the focal point of its toxicity. In 
addition, inorganic arsenic causes oxidative stress that could play a 
role in the development of adverse health effects. The NRC report 
(1999) recommended that biomarkers of inorganic arsenic exposure and 
cancer appearance be thoroughly studied. Such data might better 
characterize the dose-response effects of inorganic arsenic at lower 
exposure levels. For noncancer effects, a greater understanding of 
arsenic's effects on cellular respiration and subsequent effects of 
methylation and oxidative stress are needed (NRC, 1999).
    NRC recommended several mode of action studies, using biomarkers, 
to help predict the shape of the dose-response curve for cancer and 
non-cancer endpoints. NRC concluded that `` * * *Additional 
epidemiological evaluations are needed to characterize the dose-
response relationship for arsenic-associated cancer and non-cancer 
endpoints, especially at low doses.''
7. Risk Considerations
    The NRC study used the results of epidemiological, (i.e., human) 
studies; research on the mode of action, and information about factors 
affecting sensitivity to arsenic to project to risks to the U.S. 
population. The numerical estimation of risk in the NRC report has 
several features to consider. The range of drinking water levels 
associated with health endpoints in the available studies is generally 
hundreds of ppb which is, however, within a factor of 10 of the 
existing standard of 50 ppb. Because of uncertainty about the shape of 
the dose-response relationship below this range of observed responses, 
the NRC report used the approach of the 1996 EPA proposed carcinogen 
risk assessment guidelines (US EPA, 1996b). For the male bladder cancer 
deaths which were emphasized in the report, NRC used a lower limit on 
the dose associated with a 1% (1 in 100) cancer response, and the 
LED01 is estimated to be 400 ppb. This is a 
point of departure for extrapolating to exposure levels outside the 
range of observed data based on inference. Consistent with the proposed 
revisions to the Guidelines for Cancer Risk Assessment, the report 
shows both a linear extrapolation and a margin of exposure 
extrapolation (difference between the point of departure and selected 
exposure). Because current data on potential modes of action are 
supportive of sub-linear extrapolations, the linear approach could 
overestimate risk at low doses. However, EPA believes that within the 
several-fold range (10x) just below the point of departure, this should 
make little difference. EPA's scientists note that it makes an 
increasing difference as dose decreases, and the difference results in 
an overestimate of risk at lower exposures. With a straight-line 
extrapolation from the point of departure, the report estimated risk to 
be 1.0 to 1.5  x  10-\3\ at the current MCL of 50 ppb and the margin of 
exposure to be less than 8.
    As described further in section X.A., EPA used parts of NRC's risk 
analysis and applied U.S. water consumption, weights, and estimate of 
population exposed to arsenic to model the U.S. population risk. In 
selecting the proposed MCL, EPA considered the uncertainties of the 
quantitative dose-response assessment for inorganic arsenic's health 
effects, particularly the possible nonlinearity of the dose-response 
and multiple cancer risks. Given the current outstanding questions 
about human risk at low levels of exposure, decisions about safe levels 
are public health policy judgments.
8. Risk Characterization
    In 1983 the National Academy of Sciences (NAS, 1983) defined risk

[[Page 38902]]

assessment as containing four steps: hazard identification, dose-
response assessment, exposure assessment, and risk characterization. 
Risk characterization is the process of estimating the health effects 
based on evaluating the available research, extrapolating to estimate 
health effects at exposure levels, and characterizing uncertainties. In 
risk management, regulatory agencies such as EPA evaluate alternatives 
and select the regulatory action. Risk management considers 
``political, social, economic, and engineering information'' using 
value judgments to consider ``the acceptability of risk and the 
reasonableness of the costs of control (NAS, 1983).''
    Unlike most chemicals, there is a large data base on the effects of 
arsenic on humans. Inorganic arsenic is a human poison, and oral or 
inhalation exposure to the chemical can induce many adverse health 
conditions in humans. Specifically oral exposure to inorganic arsenic 
in drinking water has been reported to cause many different human 
illnesses, including cancer and noncancer effects, as described in 
Section III. The NRC panel (1999) reviewed the inorganic arsenic health 
effects data base. The panel members concluded that the studies from 
Taiwan provided the current best available data for the risk assessment 
of inorganic arsenic-induced cancer. (There are corroborating studies 
from Argentina and Chile.) They obtained more detailed Taiwanese 
internal cancer data and modeled the data using the multistage Weibull 
model and a Poisson regression model. Three Poisson data analyses 
showed a 1% response level of male bladder cancer at approximately 400 
g of inorganic arsenic/L. The 1% level was used as a Point of 
Departure (POD) for extrapolating to exposure levels outside the range 
of observed data.
    For an agent that is either acting by reacting directly with DNA or 
whose mode of action has not been sufficiently characterized, EPA's 
public health policy is to assume that dose and response will be 
proportionate as dose decreases (linearity of the extrapolated dose-
response curve). This is a science policy approach to provide a public 
health conservative assessment of risk. The dose-response relationship 
is extrapolated by taking a straight line from the POD rather than by 
attempting to extend the model used for the observed range. This 
approach was adopted by the NRC report which additionally noted that 
using this approach for arsenic data provides results with alternative 
models that are consistent at doses below the observed range whereas 
extending the alternative models below the observed range gives 
inconsistent results. Drawing a straight line from the POD to zero 
gives a risk of 1 to 1.5 per 1,000 at the current MCL of 50 g/
L. Since some studies show that lung cancer deaths may be 2- to 5-fold 
higher than bladder cancer deaths, the combined cancer risk could be 
even greater. The NRC panel also noted that the MCL of 50 g/L 
is less than 10-fold lower than the 1% response level for male bladder 
cancer. Based on its review, the consensus opinion of the NRC panel was 
that the current MCL of 50 g/L does not meet the EPA's goal of 
public-health protection. Their report recommended that EPA lower the 
MCL as soon as possible.

IV. Setting the MCLG

A. How Did EPA Approach It?

    For the decisions in this regulation, the EPA has relied upon the 
NRC report as presenting the best available, peer reviewed science as 
of its completion and has augmented it with more recently published, 
peer reviewed information. EPA used the 1999 NRC report and other 
published scientific papers to characterize the potential health 
hazards of ingested inorganic arsenic. As NRC (1999) noted, DMA may 
enhance the carcinogenicity of other chemicals, but more data are 
needed. Based on current knowledge, the organic forms of arsenic in 
fish and shellfish do not appear to present a significant risk to 
humans. The overall weight of evidence indicates that the inorganic 
arsenate and arsenite forms found in drinking water are responsible for 
the adverse health effects of ingested arsenic. EPA focused its risk 
assessment on the carcinogenic effects of inorganic arsenic (the forms 
found in drinking water sources).
    A factor that could modify the degree of individual response to 
inorganic arsenic is its metabolism. There is ample evidence (NRC, 
1999) that the quantitative patterns of inorganic arsenic methylation 
vary considerably and that the extent of this variation is unknown. It 
is certainly possible that the metabolic patterns of people affect 
their response to inorganic arsenic.
    There are studies underway in humans and experimental animals under 
the EPA research plan and other sponsorships. Over the next several 
years these will provide better understanding of the mode(s) of 
carcinogenic action of arsenic, metabolic processes that are important 
to its toxicity, human variability in metabolic processes, and the 
specific contributions of various food and other sources to arsenic 
exposure in the U.S. These are important issues in projecting risk from 
the observed data range in the epidemiologic studies to lower 
environmental exposures experienced from U.S. drinking water.
    Until further research is completed, questions will remain 
regarding the dose-response relationship at low environmental levels. 
The several Taiwan studies have strengths in their long-term 
observation of exposed persons and coverage of very large populations 
(>40,000 persons). Additionally, the collection of pathology data was 
unusually thorough. Moreover, the populations were quite homogeneous in 
terms of lifestyle. Limitations in exposure information exist that are 
not unusual in such studies. In ecological epidemiology studies of this 
kind, the exposure of individuals is difficult to measure because their 
exposure from water and food is not known. This results in 
uncertainties in defining a dose-response relationship. The studies in 
Chile and Argentina are more limited in extent, (e.g., years of 
coverage, number of persons, or number of arsenic exposure categories 
analyzed), but provide important findings which corroborate one another 
and those of the Taiwan studies.
    These epidemiological studies provide the basis for assessing 
potential risk from lower concentrations of inorganic arsenic in 
drinking water, without having to adjust for cross-species toxicity 
interpretation. Ordinarily, the characteristics of human carcinogens 
can be explored and experimentally defined in test animals. Dose-
response can be measured, and animal studies may identify internal 
transport, metabolism, elimination, and subcellular events that explain 
the carcinogenic process. Arsenic presents unique problems for 
quantitative risk assessment because there is no test animal species in 
which to study its carcinogenicity. While such studies have been 
undertaken, it appears that test animals, unlike humans, do not respond 
to inorganic arsenic exposure by developing cancer. Their metabolism of 
inorganic arsenic is also quantitatively different than humans. 
Inorganic arsenic does not react directly with DNA. If it did, it would 
be expected to cause similar effects across species and to cause 
response in a proportionate relationship to dose. Moreover, its 
metabolism, internal disposition, and excretion are different and vary 
across animal and plant species and humans--in test studies and in 
nature.

[[Page 38903]]

    Until more is known, EPA will take a traditional, public health 
conservative approach to considering the potential risks of drinking 
water containing inorganic arsenic. EPA recognizes that the traditional 
approach may overestimate risk, as explained in the next section.

B. What Is the MCLG?

    EPA concludes that exposure to inorganic arsenic induces cancer in 
humans. It also is associated with adverse noncancer effects such as 
hypertension (NRC, 1999). The NRC report stated that ``Data on the 
modes of action for carcinogenicity can help to predict the shape of 
cancer dose-response curves below the level of direct observation of 
tumors. * * * For arsenic carcinogenicity * * * modes of action that 
are considered most plausible (namely, indirect mechanisms of 
mutagenicity) lead to a sublinear dose-response at some point below the 
level at which a significant increase in tumors is observed. However, 
because a specific mode (or modes) of action has not been identified at 
this time, it is prudent not to rule out the possibility of a linear 
response (NRC 1999, pgs. 213-214).'' The expert panel report (US EPA, 
1997d, pg. 31) stated: ``* * * for each of the modes of action regarded 
as plausible, the dose-response would either show a threshold or would 
be nonlinear. * * * [H]owever, ``the dose response for arsenic at low 
doses would likely be truly nonlinear--i.e., with a decreasing slope as 
the dose decreased. However, at very low doses such a curve might 
effectively be linear but with a very shallow slope, probably 
indistinguishable from a threshold.'' In the absence of a known mode of 
action(s), EPA has no basis for determining the shape of a sublinear 
dose-response curve for inorganic arsenic. As a result, consistent with 
EPA public health policy, EPA will continue to use a linear dose-
response curve for inorganic arsenic effects. Using a linear type of a 
dose-response curve, EPA is proposing an MCLG of zero. The Agency 
welcomes comments on setting a nonzero MCLG and submission of data 
supporting a nonzero MCLG.

C. How Will a Health Advisory Protect Potentially Sensitive 
Subpopulations?

    The NRC report was inconclusive about the health risks to pregnant 
woman, developing fetus, infants, lactating women, and children. When 
the Agency completes this rulemaking, it intends to issue a health 
advisory on arsenic in drinking water, in order to decrease risk to 
sensitive subpopulations prior to the implementation of the new MCL. 
The effective date of a revised MCL will be three to five years after 
the final rule is issued (2004-2006).
    A health advisory is a non-regulatory document that supports water 
providers in their independent decisions on actions to take regarding 
water contaminants and their communication with the general public. In 
the health advisory on arsenic the Agency intends to address a 
precautionary step to protect infants. This step would be to avoid 
using water containing high levels of arsenic to make up infant 
formula. The reason for this precaution is that epidemiologic studies 
indicate that arsenic in drinking water (Lewis et al., 1999) affects 
the cardiovascular system. While there are no studies of effects of 
arsenic on human infants, both the cardiovascular system and brain (and 
its vascular system) continue to develop after birth (Thompson, P.M et 
al. 2000); thus, the effects discussed in this notice on the 
cardiovascular system raise a concern about potential effects of 
arsenic on infant development. In large part, causes of cerebrovascular 
incidents (stroke) in children are not understood except for certain, 
known associations with organic diseases and genetic diseases. 
Congenital and acquired heart disease are the most common cause of 
stroke in children. The current toxicity data on arsenic do not 
contradict this precautionary view.

D. How Will the Clean Water Act Criterion Be Affected by This 
Regulation?

    EPA is also working to harmonize the human health arsenic criteria 
for the Clean Water Act (CWA) and the SDWA. The major reason for the 
present difference (discussed in section II.D.) between the MCL and the 
Ambient Water Quality Criterion (AWQC) was the result of using separate 
bases for determining the two standards. The AWQC for arsenic was 
derived from the risk assessment for arsenic-induced skin cancer, while 
the current SDWA MCL, adopted in 1975 as a National Interim Primary 
Drinking Water Regulation, evolved from the U.S. Public Health Service 
standard dating back to the 1940s. The Agency will use the conclusions 
of the NRC (1999) report to form the human health basis for both the 
AWQC and the MCL. However, the CWA and SDWA statutes require that the 
Agency consider different factors during the derivation of a standard. 
For example, SDWA requires that the Agency consider: (1) Cost/benefit 
analyses, including sizes of the public water systems, (2) the level of 
arsenic that can be analyzed by laboratories on a routine basis, [i.e., 
the practical quantitation limit (PQL)] and (3) treatment techniques 
for removing the chemical from the water. On the other hand, the CWA 
requires the EPA to consider water and fish consumption (including 
amount of fish eaten, percent lipid in the fish and the bioaccumulation 
factor for the chemical in the fish), but not cost/benefits, analytical 
or treatment techniques. Accordingly, developing a AWQC under the CWA 
may produce a standard that differs from the MCL derived under the SDWA 
even though both standards are based on the same health endpoint. The 
Agency will begin work on a new AWQC for arsenic after promulgating the 
MCL for arsenic.

V. EPA's Estimates of Arsenic Occurrence

    One of the key components in the development of the proposed 
arsenic rule is the analysis of arsenic occurrence in public water 
supplies, both community water systems (CWS) and non-transient, non-
community, water systems (NTNCWS). EPA's national occurrence assessment 
of arsenic provides a basis for estimating:
    (1) The number of systems expected to exceed various arsenic 
levels;
    (2) the number of people exposed to the different levels of 
arsenic; and
    (3) the variability in arsenic levels in water systems among the 
wells and/or entry points to the distribution system.

EPA uses the estimate of the total number of systems and populations 
affected in the United States in its cost-benefit analysis. EPA is 
seeking comment on its analysis of arsenic occurrence in the U.S., as 
well as requesting additional data.

A. What Data Did EPA Evaluate?

    For previous occurrence analyses EPA used four older national 
arsenic databases: (1) The National Inorganic and Radionuclide Survey 
(NIRS), conducted from 1984 to 1986, for ground water CWSs; (2) a 1976-
1977 National Organic Monitoring Survey (NOMS); (3) a 1978-1980 Rural 
Water Survey (RWS); and (4) the 1978 Community Water System Survey 
(CWSS) for surface water CWSs. However, these older databases have 
several limitations. First, the surveys of surface water systems will 
not reflect changes in raw water sources which occurred in the last 
twenty years. Second, filtration treatment added to comply with the 
Surface Water Treatment Rule (110 54 FR 27486, June 29, 1989) would 
tend to decrease arsenic exposure, through incidental arsenic removal. 
Finally, most of the

[[Page 38904]]

data were censored (reported as less than the analytical test method 
detection level or reporting limit, e.g., ``not detected'' or ``5 
g/L''). NIRS, CWSS, and RWS, respectively, had 93%, 97%, and 
90% censored data. This limits the estimation of low level occurrence 
of arsenic and makes it statistically difficult to extrapolate 
occurrence with the limited amount of non-censored data. The EPA 
Science Advisory Board recommended that EPA abandon the older data when 
sufficient new data become available because of the high percentage of 
censored data in the older surveys and the difficulty of using highly 
censored data sets to estimate occurrence (US EPA, 1995). Therefore, 
with improved analytical techniques for detecting arsenic at lower 
levels, as low as 0.5 g/L, and the lower reporting limits in 
the new data received by EPA, the Agency focused the data evaluation on 
post-1980 data sources for estimating national occurrence.
    Since 1992, EPA OGWDW has received arsenic databases from other EPA 
offices, States, public water utilities, and associations. EPA combined 
the compliance monitoring data obtained from States into the ``25 
States'' database. The Agency evaluated the databases listed in Table 
V-1. (Note that EPA's database, the Safe Drinking Water Information 
System (SDWIS), only records violations of the current arsenic MCL, so 
it is censored at 50 g/L.) A more detailed description of the 
databases and evaluations are presented in the EPA document titled 
``Arsenic Occurrence in Public Drinking Water Supplies,'' (US EPA, 
2000b).

                                   Table V-1.--Summary of Arsenic Data Sources
----------------------------------------------------------------------------------------------------------------
                                 Reporting level
          Data source            (g/L)    Number of CWSs        Source water            Water type
----------------------------------------------------------------------------------------------------------------
25 States\1\..................  1 to 10.........  >19,000.........  Surface, Ground......  finished.
Metro \2\.....................  1...............  140.............  Surface, Ground......  raw & finished.
NAOS \3\......................  0.5.............  517.............  Surface, Ground......  raw & predicted
                                                                                            finished.
USGS \4\......................  1...............  not available     Ground...............  raw.
                                                   (20,000 sites).
ACWA \5\......................  0.1 to 1........  180 (1,500        Surface, Ground......  finished.
                                                   samples).
WESTCAS \6\...................  not available...  not available...  Ground...............  finished.
----------------------------------------------------------------------------------------------------------------
\1\ Arsenic compliance monitoring data from community water systems (CWSs) from Alabama, Alaska, Arizona,
  Arkansas, California, Illinois, Indiana, Kentucky, Kansas, Maine, Michigan, Minnesota, Missouri, Montana,
  Nevada, New Hampshire, New Jersey, New Mexico, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Texas,
  and Utah.
\2\ Metropolitan Water District of Southern California (MWDSC, or Metro) 1992-1993 national survey of 140 CWSs
  serving more than 10,000 people.
\3\ 1996 National Arsenic Occurrence Survey (NAOS) funded by the Water Industry Technical Action Fund (WITAF),
  which includes the following organizations: American Water Works Association, National Association of Water
  Companies, Association of Metropolitan Water Agencies, National Rural Water Association, and National Water
  Resources Association.
\4\ U.S. Geological Survey (USGS) ambient (raw water) ground water from approximately 20,000 wells throughout
  the U.S. used for various purposes, including public supply, research, agriculture, industry and domestic
  supply.
\5\ 1993 survey from 180 water agencies, utilities, and cities in southern California, conducted by the
  Association of California Water Agencies (ACWA).
\6\ 1997 Western Coalition of Arid States (WESTCAS) Research Committee Arsenic Occurrence Study which aggregated
  arsenic data (e.g., median arsenic value for county, city, or provider) from Arizona, New Mexico, and Nevada.

B. What Databases Did EPA Use?

    EPA evaluated the databases for representativeness, accuracy and 
coverage of community water systems in the U.S. EPA determined that the 
compliance monitoring data from the 25 States (``25-States database'') 
would establish the most accurate and scientifically defensible 
national occurrence and exposure distributions of arsenic in public 
ground water and surface water supplies. Figure V.1 shows the coverage 
of these States in the U.S. The 25-States database provides more 
finished water arsenic data, from over 19,000 ground and surface water 
CWSs, than the other national databases. EPA is interested in finished 
water data, rather than raw water data, because it indicates the 
current arsenic levels in water systems after treatment and reflects 
their customers' level of exposure to arsenic. The 25-States database 
provides system and individual arsenic data for a significant number of 
CWSs in each State. The arsenic data can be linked directly to specific 
water systems by their identification code to obtain additional 
information in SDWIS, such as population served, system type (e.g., 
CWS, NTNCWS), source type (e.g., ground water, surface water, purchased 
water, ground water under the influence), and location. For this 
reason, EPA chose to use the compliance monitoring data from the States 
of California, Nevada, New Mexico, and Arizona, rather than the data 
about these States from ACWA and WESTCAS.
    Most of the 25-States data had reporting limits of less than 2 
g/L. In addition, the database includes multiple samples from 
the water systems over time and from multiple sources within the 
systems. The multiple samples provide for a more accurate estimate of 
the arsenic levels in the systems, than a survey with one sample per 
system. The arsenic compliance monitoring data provides point-of-entry 
or well data within systems from eight States, which is used for 
intrasystem variability analysis (discussed in Section V.G). 
Intrasystem variability analysis provides an understanding of the 
variation of arsenic levels within a system, from well to well or entry 
point to entry point.
    EPA also received arsenic data from Florida, Idaho, Iowa, 
Louisiana, Pennsylvania, and South Dakota; however EPA did not include 
these States in the database. These States either provided data that 
(1) could not be linked to CWSs; (2) did not indicate if the results 
were censored or non-censored; (3) were all zero, without providing the 
analytical/reporting limit; or (4) rounded results to the nearest ten 
g/L.
    EPA used the USGS and NAOS databases and their occurrence estimates 
for comparison purposes. In addition, EPA used the NAOS approach to 
partitioning of the U.S. for its analysis.
    We combined State data sets with different data naming conventions, 
and the database development and data

[[Page 38905]]

conditioning process is described in Appendix D-3 of the occurrence 
support document (US EPA, 2000b). Appendix D-1 identifies who provided 
the data and data provided for each State in the 25-State database. 
Appendix D-2 lists the data names we used to develop the national 
database. We assumed that the data represented compliance sampling, and 
some States have reportedly provided source water data and compliance 
data. If you are aware of errors in our data set, please let us know. 
Also, additional data would reduce the uncertainty of our national 
occurrence estimate. We encourage commenters to submit arsenic 
compliance monitoring data sets either from States not already in our 
data set, more recent data that were not included in the described data 
sets, or a more official version of compliance data. We will use this 
information to obtain a more representative national occurrence 
estimate for the final rule.
BILLING CODE 6560-50-P

[[Page 38906]]

[GRAPHIC] [TIFF OMITTED] TP22JN00.000

BILLING CODE 6560-50-C

[[Page 38907]]

C. How Did EPA Estimate National Occurrence of Arsenic in Drinking 
Water?

    EPA derived the national estimates of arsenic occurrence in three 
steps: (1) Estimate system means; (2) estimate State distribution of 
system means; and (3) estimate national distributions of system means.
    As discussed in section V.B, EPA determined that the 25-States 
database would be used for estimating national occurrence. EPA 
calculated a system average for each water system in its database. When 
the database provided 5 or more detected (greater than the reporting 
limit) arsenic samples in a system, we used the method of ``regression 
on order statistics'' (Helsel and Cohn, 1988) to extrapolate values for 
the non-detected observations, then calculated the arithmetic mean. 
When there were 1 to 4 detected values, we substituted half the 
reporting limit for each non-detected value (less than the reporting 
limit) and calculated an arithmetic average. When there were no 
detected values (all samples had non-detected values), we set the 
arsenic system average as a non-detect at the mode (most frequently 
occurring) of the reporting limits. As a result, each system has a 
calculated system mean, either a non-detected or detected value.
    In order to estimate the distribution of systems means in a State, 
EPA aggregated the system means into a single distribution and derived 
separate estimates of percentage of systems with average arsenic values 
greater than 2, 3, 5, 10, 15, 20, 25, 30, 40, and 50 g/L 
(referred to as exceedance estimates). We developed separate estimates 
for ground water and surface water systems. Within each State, EPA fit 
a lognormal distribution to the population of estimated system means, 
and used the fitted distribution to estimate exceedance probabilities. 
However, when fitting the lognormal distribution, EPA excluded system 
means which were estimated to be less than their reporting limit, since 
these require more extrapolation below the reporting limit and were 
judged to be less reliable. EPA also did not make exceedance estimates 
below the most frequently occurring reporting limit or censoring point 
in each of the States.
    To estimate the national distribution of system means, EPA grouped 
the States into the seven regions developed in the NAOS (Frey and 
Edwards, 1997). Frey and Edwards derived a natural occurrence factor by 
weighting detection, number of data points, and higher arsenic values 
from data in the USGS WATSTORE water quality database and the Metro 
survey. Then they grouped States into seven regions based on the 
calculated natural occurrence factors. Figure V.1 is a map of the U.S. 
with the NAOS regions. With this regional grouping of States, EPA 
developed separate regional estimates for surface water and ground 
water systems. In a separate analysis, EPA found the national result 
from using the NAOS regions to be similar to grouping States into 
different regions, based on a preliminary examination of generally 
related exceedance probabilities.
    EPA derived each regional estimate by using exceedance estimates 
from the States with compliance monitoring data in the region, weighted 
by the number of community water systems in those specific States. For 
example, we used the exceedance estimates from Montana and North 
Dakota, weighted by the number of community water systems in those 
States, to derive the North Central region estimate. Within each 
region, we estimated the percentages of systems with average arsenic 
values greater than 2, 3, 5, 10, 15, 20, 25, 30, 40, and 50 g/
L. We then weighted the regional exceedance estimates, by the total 
number of community water systems in each region (including the number 
of community water systems in the States without compliance monitoring 
data) to obtain national estimates of percentages of systems with 
average arsenic values greater than 2, 3, 5, 10, 15, 20, 25, 30, 40, 
and 50 g/L.
    EPA believes that separate estimates are not justified for 
different system sizes. A graphical analysis (``box and whisker'' 
plots) of the occurrence distributions suggests that in some regions, 
systems in different size categories do have different mean 
concentrations. However the differences in means are much smaller than 
the variability of the observed concentrations. Moreover, the 
differences do not vary with system size in a consistent way. For 
example, for ground water systems, arsenic concentrations in the New 
England Region (NAOS Region 1) decrease as system size increases, while 
in the Mid-Atlantic and South Central regions (NAOS Regions 2 and 5), 
arsenic concentrations increase as system size increases. In the four 
remaining regions, no systematic patterns are evident. For these 
reasons, and because additional stratification decreases the precision 
of the estimates, EPA has not developed separate estimates for 
different system sizes.
    The method of substitution that EPA used for non-detected 
concentrations (described above) is different from the method that 
water systems use for determining compliance with the MCL: We 
substituted positive values for non-detects, while for purposes of 
compliance, non-detected concentrations are treated as zero. Therefore, 
our estimates of occurrence will be higher on average than those found 
by water systems monitoring for compliance with the MCL. As a result we 
might overestimate both the costs and benefits of the proposed MCL. 
However we believe that our estimate of occurrence is justified, for 
two reasons. First, it is more accurate (less biased). Second, as the 
detection limits of analytical methods continue to improve (i.e., lower 
than 1 g/L), the difference between the two substitution 
methods will be small and will occur in the range below the MCL.

D. What Are the National Occurrence Estimates of Arsenic in Drinking 
Water for Community Water Systems?

    Arsenic is found in both ground water and surface water sources. 
Figure V.1 presents the regions of the United States referred to in 
this discussion. Table V-2 data indicate that higher levels of arsenic 
tend to be found in ground water sources (e.g., aquifers) than in 
surface water sources (e.g., lakes, rivers). The 25-States finished 
water data also indicate that the North Central, Midwest Central, and 
New England regions of the United States tend to have low to moderate 
(2-10 g/L) ground water arsenic levels, while the Western 
region tends to have higher levels of ground water arsenic (>10 
g/L) than the other regions. Systems in the other regions of 
the U.S. may have high levels of arsenic (hot spots), while many 
systems and portions of the States in the listed regions may not have 
any detected arsenic in their drinking water.

[[Page 38908]]



                                           Table V-2.--Regional Exceedance Probability Distribution Estimates
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                           Percent of systems exceeding arsenic concentrations (g/L) of:
                              Region                               -------------------------------------------------------------------------------------
                                                                       2        3        5       10       15      20       25       30      40      50
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  Ground Water Systems
--------------------------------------------------------------------------------------------------------------------------------------------------------
New England.......................................................     29       21      21      7         4      3         2        2      1       0.7
Mid Atlantic......................................................  .......  .......    *0.3   *1         0.3    0.1       0.06     0.03   0.009   0.003
South East........................................................      2        1       0.5    0.2       0.1    0.07      0.05     0.04   0.02     .01
Midwest...........................................................     28       21      14      6         4      2         2        1       .8     0.5
South Central.....................................................     27       19      10      4         2      1         0.8      0.5    0.3     0.2
North Central.....................................................     29       21      13      6         4      2         2        1      0.9     0.6
West..............................................................     42       31      25     12         7      5         4        3      2       1
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  Surface Water Systems
--------------------------------------------------------------------------------------------------------------------------------------------------------
New England.......................................................     11       *8      *9      1.0       0.6    0.4       0.3      0.3    0.2     0.1
Mid Atlantic......................................................  .......  .......    *0.1   *0.1       0.01   0.001     0        0      0       0
South East........................................................      0.8      0.2     0.03   0.001     0      0         0        0      0       0
Midwest...........................................................      4        3       1      0.4       0.2    0.1       0.1      0.07   0.05    0.03
South Central.....................................................      9        4       1      0.3       0.1    0.08      0.05     0.03   0.02    0.01
North Central.....................................................     20       10       4      0.8       0.2    0.1       0.05     0.02   0.008   0.003
West..............................................................     19       13       7      3         2      1         0.8      0.6    0.4     0.3
--------------------------------------------------------------------------------------------------------------------------------------------------------
*Estimates at these regions and levels are inconsistent, in that the estimated % exceedances at lower values are smaller than the estimates at higher
  values. This inconsistency occurs because fewer States were used to estimate % exceedances at lower levels. EPA did not attempt to resolve the
  inconsistency, but combined the regional distribution into a national distribution which is consistent.

    The estimates of the number of CWSs expected to exceed different 
arsenic levels is based on the distribution of average arsenic 
concentrations in water systems. Using the data from the 25-States 
database, EPA estimates that 5.4% of ground water CWSs and 0.7% of 
surface CWSs have average arsenic levels above 10 g/L. 
Similarly, 12.1% and 2.9% of ground water CWSs and surface water CWSs, 
respectively, have average arsenic levels above 5 g/L. Tables 
V-3 and V-4 provide estimates by system size category. The percentage 
of systems that have average arsenic levels within a specific range 
does not vary across the system size categories. For example, 2.3% of 
ground water systems in each of the five system size categories have 
average arsenic levels in the range of >10 g/L to 15 
g/L. Therefore, the arsenic exceedance estimates have the same 
distribution in any system size. These estimates of percent (or 
probability) of systems that have average arsenic levels within a 
specific range are multiplied by the number of systems in each size 
category to derive the number of systems in Table V-3 and V-4.

                Table V-3.--Statistical Estimates of Number of Ground Water CWSs With Average Arsenic Concentrations in Specified Ranges
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                        Number of systems with average arsenic concentrations in specified ranges (g/L; 43,749
                                                                                                 systems total)
           System size (population served)            --------------------------------------------------------------------------------------------------
                                                                   >2.0 to    >3.0 to    >5.0 to    >10.0 to   >15.0 to   >20.0 to   >30.0 to
                                                          2.0        3.0        5.0        10.0       15.0       20.0       30.0       50.0      >50.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
25 to 500............................................     21,325      2,158      2,268      1,960        674        314        287        188        129
501 to 3,300.........................................      7,616        771        810        700        241        112        103         67         46
3,301 to 10,000......................................      1,811        183        193        167         57         27         24         16         11
10,001 to 50,000.....................................        933         94         99         86         29         14         13          8          6
>50,000..............................................        154         16         16         14          5          2          2          1          1
    Total............................................     31,840      3,221      3,386      2,927      1,006        468        429        280        192
    (% of systems)...................................    (72.8%)     (7.4%)     (7.7%)     (6.7%)     (2.3%)     (1.1%)     (1.0%)     (0.6%)    (0.4%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Totals may not add up due to rounding of the number of systems to the nearest whole number. Systems serving fewer than 25 people are not included
  in this table. The estimates in this table do not take into account most treatment in place; in particular most of the systems in the ``>50.0'' column
  will have treated for arsenic in order to reduce their concentration below 50 g/L. See text for more details.

    In Tables V-3 and V-4, the estimated numbers of systems with mean 
concentrations above 50 g/L do not represent the number of 
systems which are believed to be out of compliance with the current MCL 
of 50 g/L; nor do they represent actual systems at all. 
Rather, they are statistical extrapolations above 50 g/L, 
based primarily on data below 50 g/L. Since most data below 50 
g/L comes from systems which have not treated for arsenic, the 
``>50.0'' columns in Tables V-3 and V-4 do not take into account most 
treatment currently in place. Therefore, the ``>50.0'' columns 
represent the estimated number of systems which would have mean arsenic 
concentrations above 50 g/L if they had not treated for 
arsenic. By comparison with Tables V-3 and V-4, during the three-year 
period from September 1994 through August 1997, EPA recorded a total of 
14 samples from 10 public water systems in which arsenic concentrations 
exceeded 50 g/L.

[[Page 38909]]



                Table V-4.--Statistical Estimates of Number of Surface Water CWSs With Average Arsenic Concentrations in Specified Ranges
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                        Number of systems with average arsenic concentrations in specified ranges (g/L; 10,683
                                                                                                 systems total)
           System size (population served)            --------------------------------------------------------------------------------------------------
                                                                   >2.0 to    >3.0 to    >5.0 to    >10.0 to   >15.0 to   >20.0 to   >30.0 to
                                                           2.0       3.0        5.0        10.0       15.0       20.0       30.0       50.0      >50.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
25 to 500............................................      2,794        122         94         69         11          4          4          2          2
501 to 3,300.........................................      3,308        144        111         82         13          5          4          3          2
3,301 to 10,000......................................      1,656         72         56         41          6          3          2          1          1
10,001 to 50,000.....................................      1,384         60         47         34          5          2          2          1          1
> 50,000.............................................        477         21         16         12          2          1          1          0          0
    Total............................................      9,622        419        323        239         37         15         13          8          7
    (% of systems)...................................    (90.1%)     (3.9%)     (3.0%)     (2.2%)     (0.4%)     (0.1%)     (0.1%)     (0.1%)    (0.1%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Totals may not add up due to rounding of the number of systems to the nearest whole number. Systems serving fewer than 25 people are not included
  in this table. The estimates in this table do not take into account most treatment in place; in particular most of the systems in the ``>50.0'' column
  will have treated for arsenic in order to reduce their concentration below 50 g/L. See text for more details.

E. How Do EPA's Estimates Compare With Other Recent National Occurrence 
Estimates?

    In addition to EPA's national occurrence results presented in 
section V.D., two additional studies recently developed national 
occurrence estimates for arsenic in drinking water: the NAOS study 
(Frey and Edwards, 1997), and the USGS study of arsenic occurrence in 
ground water (USGS, 2000). The databases that supported the NAOS and 
USGS estimates are briefly described in section V.A., ``What data did 
EPA evaluate?'' Each of these occurrence estimates was developed in a 
slightly different manner. Whereas EPA's occurrence estimates are based 
on compliance monitoring data from more than 19,000 CWSs in 25 states, 
the NAOS occurrence estimates are based on a stratified random sampling 
from representative groups defined by source type, system size, and 
geographic location. The NAOS database contains 435 predicted finished 
water arsenic data points (derived from raw water arsenic 
concentrations and treatment information), from more than 400 CWSs. The 
USGS analysis is based on arsenic ambient (untreated, or raw water) 
ground water data, providing 17,496 samples for 1,528 counties (with 5 
or more data points) in the United States (out of a total of 3,222 
counties). USGS derived exceedance estimates for each county by 
calculating the percentage of data points in each county exceeding 
specific concentrations, from 1 g/L to 50 g/L. Then 
USGS associated the percentages for each county with the number of CWSs 
that use ground water in these counties, which was based on data 
derived from SDWIS. This information was aggregated for all of the 
appropriate counties to derive the national estimates for ground water 
CWSs. USGS did not have estimates for surface water CWSs.

    Table V-5.--Comparison of CWSs From EPA, NAOS, and USGS Estimates
                    Exceeding Arsenic Concentrations
------------------------------------------------------------------------
                                EPA GW   NAOS GW &
       % CWS exceeding           &SW         SW       EPA GW    USGS GW
                              (percent)  (percent)  (percent)  (percent)
------------------------------------------------------------------------
2 g/L..............       24.1       21.7       27.2       25.0
5 g/L..............       10.3       11.5       12.1       13.6
10 /L..............        4.5        4.5        5.4        7.6
------------------------------------------------------------------------

    Table V-5 compares the EPA, NAOS, and USGS estimates of the percent 
of samples exceeding various arsenic concentrations. At a concentration 
of 2 g/L, the EPA national exceedance estimate for both 
surface water and ground water CWSs (24.1 percent) is higher than the 
NAOS estimate (21.7 percent). At 5 g/L, the EPA and NAOS 
predicted exceedance probabilities are relatively similar (10.3 and 
11.5 percent, respectively). These two estimates are the same at 10 
g/L (4.5 percent). For ground water CWSs, the USGS and EPA 
estimates are also relatively similar. At 2 g/L, the EPA 
national ground water exceedance estimate (27.2 percent) is slightly 
higher than the USGS estimate (25.0 percent). At 5 and 10 g/L, 
the USGS exceedance estimates (13.6 percent and 7.6 percent, 
respectively) are slightly higher than the EPA estimates (12.1 percent 
and 5.4 percent). This comparison of exceedance probabilities suggests 
that EPA's arsenic occurrence projections based on compliance 
monitoring data are relatively close to the NAOS and USGS projections 
through the range of this comparison. In addition, the USGS estimates 
are expected to be slightly higher than the EPA estimates for ground 
water, because they are based on raw water arsenic levels (untreated).

F. What Are the National Occurrence Estimates of Arsenic in Drinking 
Water for Non-Transient, Non-Community Water Systems?

    The 25-States database contains data for non-transient, non-
community water systems (NTNCWSs) in 15 States (two additional States 
only provided data from two systems). NTNCWSs are public water systems 
that regularly serve at least 25 of the same persons more than 6 months 
a year. Most NTNCWSs serve less than 3,300 people (99.5%) and use 
ground water (96%).
    EPA calculated basic statistics for ground water CWSs and NTNCWSs 
in each of these States. EPA compared the data and found that arsenic 
distributions in NTNCWSs are quite

[[Page 38910]]

similar to arsenic distributions in CWSs. In general, the means, 
standard deviations, and level of censoring for CWSs in a particular 
State are very close to the levels observed in NTNCWSs in that State. 
In some States, mean levels are slightly higher in CWSs than in 
NTNCWSs, whereas in others, mean levels are slightly lower in CWSs. 
There is no clear pattern and the differences are relatively minor, 
suggesting that any differences are due to random variation, rather 
than systematic underlying differences between NTNCWSs and CWSs. As a 
result, the occurrence distributions for CWSs were used to derive the 
occurrence distributions for NTNCWS systems. If the NTNCWSs data from 
the 15 States were used to derive the estimates, there would have been 
less spatial coverage of United States, which would have resulted in 
more uncertainty in the estimate. The NTNCWSs estimates are presented 
in Tables V-6 and V-7.
    As in the case of Tables V-3 and V-4, the estimated numbers of 
systems in Tables V-6 and V-7 with mean concentrations above 50 
g/L do not represent the number of systems which are believed 
to be out of compliance with the current MCL of 50 g/L; nor do 
they represent actual systems at all. Rather they represent the 
estimated number of systems which would have mean arsenic 
concentrations above 50 g/L if they had not treated for 
arsenic. By comparison with Tables V-6 and V-7, during the three-year 
period from September 1994 through August 1997, EPA recorded a total of 
14 samples from 10 public water systems in which arsenic concentrations 
exceeded 50 g/L.

               Table V-6.--Statistical Estimates of Number of Ground Water NTNCWSs With Average Arsenic Concentrations in Specified Ranges
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                        Number of systems with average arsenic concentrations in specified ranges (g/L; 19,293
                                                                                                 systems total)
           System size (population served)            --------------------------------------------------------------------------------------------------
                                                                   >2.0 to    >3.0 to    >5.0 to    >10.0 to   >15.0 to   >20.0 to   >30.0 to
                                                          2.0        3.0        5.0        10.0       15.0       20.0       30.0       50.0      >50.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
25 to 500............................................     12,088      1,223      1,285      1,111        382        178        163        106         73
501 to 3,300.........................................      1,902        192        202        175         60         28         26         17         11
3,301 to 10,000......................................         43          4          5          4          1          1          1          0          0
10,001 to 50,000.....................................          8          1          1          1          0          0          0          0          0
> 50,000.............................................          0          0          0          0          0          0          0          0          0
    Total............................................     14,041      1,421      1,493      1,291        444        206        189        123         85
    (% of systems)...................................    (72.8%)     (7.4%)     (7.7%)     (6.7%(     (2.3%)     (1.1%)     (1.0%)     (0.6%)    (0.4%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Totals may not add up due to rounding of the number of systems to the nearest whole number. Systems serving fewer than 25 people are not included
  in this table. The estimates in this table do not take into account most treatment in place; in particular most of the systems in the ``>50.0'' column
  will have treated for arsenic in order to reduce their concentration below 50 g/L. See text for more details.


              Table V-7.--Statistical Estimates of Number of Surface Water NTNCWSs With Average Arsenic Concentrations in Specified Ranges
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Number of systems with average arsenic concentrations in specified ranges (``g/L; 764
                                                                                                 systems total)
           System size (population served)            --------------------------------------------------------------------------------------------------
                                                                   >2.0 to    >3.0 to    >5.0 to    >10.0 to   >15.0 to   >20.0 to   >30.0 to
                                                          2.0        3.0        5.0        10.0       15.0       20.0       30.0       50.0      >50.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
25 to 500............................................        502         22         17         12          2          1          1          0          0
501 to 3,300.........................................        163          7          5          4          1          0          0          0          0
3,301 to 10,000......................................         18          1          1          0          0          0          0          0          0
10,001 to 50,000.....................................          4          0          0          0          0          0          0          0          0
50,000...............................................          2          0          0          0          0          0          0          0          0
    Total............................................        688         30         23         17          3          1          1          1          0
    (% of systems)...................................    (90.1%)     (3.9%)     (3.0%)     (2.2%)     (0.4%)     (0.1%)     (0.1%)     (0.1%)    (0.1%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Totals may not add up due to rounding of the number of systems to the nearest whole number. Systems serving fewer than 25 people are not included
  in this table. The estimates in this table do not take into account most treatment in place; in particular most of the systems in the ``>50.0'' column
  will have treated for arsenic in order to reduce their concentration below 50 g/L. See text for more details.

G. How Do Arsenic Levels Vary From Source To Source and Over Time?

    EPA analyzed the variability of arsenic concentrations within a 
system, from well to well or entry point to entry point (sampling 
point). This analysis allows EPA to estimate the number of sampling 
points in a system that may be above the proposed MCL and to improve 
estimation of the treatment costs for systems with multiple sampling 
points. The result of the intrasystem analysis is a constant 
coefficient of variation (CV), which is one of the inputs to the cost-
benefit computer modeling. EPA analyzed six of the eight States that 
provided intrasystem data: California, Utah, New Mexico, Oklahoma, 
Illinois and Indiana. Arkansas and Alabama were not analyzed because 
these States had very little occurrence of arsenic and almost all of 
the arsenic values were below the detection limit. After statistical 
analysis of 127 systems with five or more sampling points, EPA derived 
an arithmetic average CV of 0.64 or 64%. The EPA document titled 
``Arsenic Occurrence in Public Drinking Water Supplies,'' presents this 
statistical analysis (US EPA, 2000b).
    USGS examined its raw water arsenic data to assess the variability 
of arsenic levels over time and to determine whether there are temporal 
trends (USGS, 2000). Data came from about 350 wells with 10 or more 
arsenic analyses collected over different time periods. These wells 
were used for various purposes, such as public supply, research, 
agriculture, industry, and domestic supply, and encompassed non-potable 
and potable water quality. USGS conducted a regression analysis

[[Page 38911]]

of arsenic concentration and time for each well and found that most of 
the wells had little or no change in concentration over time (low ``r-
squared'' values when arsenic concentrations were regressed with time). 
Arsenic levels for most of the wells probably do not consistently 
increase or decrease over time. In addition, USGS found that well depth 
had no relationship to temporal variability. To determine the extent of 
the temporal variability, EPA analyzed the CVs for the mean arsenic 
level in the wells. More than 100 wells had a CV and standard deviation 
of zero. Most of these wells consistently had arsenic concentrations 
below the detection limit of 1 g/L. EPA examined the CVs for 
the other wells in relation to the mean arsenic level and found a 
relatively constant CV on the lognormal scale. The geometric mean of 
the CVs, excluding CVs of zero, is 0.39 or 39%. The report (USGS, 2000) 
listed several factors that may contribute to this variability, 
including natural variability in geochemistry or source of 
contamination, sampling technique, and changes in pumping over time.

H. How Did EPA Evaluate Co-Occurrence?

    Sections 1412(b)(3)(C)(i)(II), (III) and (VI) of the SDWA, as 
amended in 1996, require EPA to take into account activities under 
preceding rules which may have impacts on each new successive rule. To 
fulfill this need EPA began the analysis of the co-occurrence of 
drinking water contaminants. The information on co-occurrence will be 
used to determine the level of overlap in regulatory requirements. For 
example, this will include cases where treatment technologies applied 
for one regulation may resolve monitoring and/or additional treatment 
needs for another regulation or where water utilities may incur costs 
for installing multiple treatments to address other co-occurring 
substances. This information may also be used to show where specific 
levels of one contaminant may interfere with the treatment technology 
for another.
1. Data
    For the co-occurrence analysis, EPA relied on data from the 
National Water Information System (NWIS), a U.S. Geological Survey 
(USGS) database. The NWIS database was used for several reasons:
     It contains both ground and surface water data;
     It is national in scope, representing raw water samples 
from approximately 40,000 observation stations across the U.S.; and
     It provides latitude/longitude coordinates for monitoring 
stations, which can be used in subsequent analyses to associate with 
Public Water Supply Systems.
    NWIS contains a water quality data storage retrieval system 
developed by the USGS Water Resources Division. NWIS is a distributed 
water database; data can be processed over a network of computers at 
USGS offices throughout the U.S. The system comprises the Automated 
Data Processing System, the Ground Water Site Inventory System, the 
Water-Quality System, and the Water-Use Data System. NWIS does not 
represent Public Water Supply Systems directly but can be associated 
with them because it provides latitude/longitude coordinates for 
monitoring stations.
    Using the NWIS data, arsenic was analyzed with 18 other 
constituents. The other constituents included: Sulfate, radon, radium, 
uranium, nitrate, antimony, barium, beryllium, cadmium, chromium, 
cyanide, iron, manganese, mercury, nickel, nitrite, selenium, thallium, 
hardness, and total dissolved solids. An additional set of ancillary 
parameters were selected for use as indicators of the hydrogeologic and 
geochemical conditions that could influence the co-occurrence of 
specific constituents. These ancillary parameters included: turbidity, 
conductance, dissolved oxygen, pH, alkalinity, well depth, and depth 
below land.
2. Results of the Co-occurrence Analysis (US EPA, 1999f)
    Dissolved arsenic was observed to have 5442 detected counts and 
total arsenic was observed to have 1273 detected counts in the database 
at the minimal threshold level of 2 g/L. The national co-
occurrence estimates derived from the USGS NWIS data revealed several 
correlations between arsenic/sulfate and arsenic/iron at the threshold 
levels chosen by EPA as likely to affect treatment (see section VIII.). 
First, a significant correlation was observed between dissolved arsenic 
and sulfate in surface water and ground water samples at the national 
level. The analysis of the surface and ground water data from EPA 
Regions 1, 2, 4, 5, 6, 7, 8, 9 and 10 show 339 co-occurrence frequency 
counts of the data above the threshold values of dissolved arsenic >5 
g/L and sulfate >250 mg/L (Table V-8). For total arsenic and 
sulfate there are 143 co-occurrence frequency counts for the same 
threshold levels. There was no significant co-occurrence of arsenic and 
sulfate in EPA Region 3. Secondly, a correlation was observed between 
dissolved arsenic and iron and total arsenic and iron in surface and 
ground waters from EPA Regions 1, 2, 4, 5, 7, 8 and 9 (Table V-8). 
There are 562 co-occurrence frequency counts of the data above the 
threshold levels of dissolved arsenic >5 g/L and iron >300 
g/L. There are 542 co-occurrence frequency counts of the data 
above the threshold values of total arsenic >5 g/L and iron 
>300 g/L. There was no significant co-occurrence of arsenic 
and iron in EPA Regions 3, 6 and 10.

  Table V-8.--Correlation of Arsenic With Sulfate and Iron (Surface and
                             Ground Waters)
------------------------------------------------------------------------
                                              Correlation
                          Arsenic types      elements and     Frequency
      EPA regions       (threshold levels   their threshold     counts
                         >5 g/L)        level
------------------------------------------------------------------------
1, 2, 4, 5, 6, 7, 8,    Dissolved Arsenic  Sulfate (>250 mg/         339
 9, 10.                                     L).
                        Total Arsenic....  Sulfate (>250 mg/         143
                                            L).
1, 2, 4, 5, 7, 8, 9...  Dissolved Arsenic  Iron (>300                562
                                            g/L).
                        Total Arsenic....  Iron (>300                542
                                            g/L).
------------------------------------------------------------------------

    The results also show some co-occurring pairs of arsenic with 
radon. This appears to occur in EPA Regions 5 and 6 for ground water. 
However, the co-occurrence of arsenic and radon at levels of concern is 
not significant (Table V-9). At present, the analysis does not show 
significant co-occurring pairs between arsenic and radon in surface 
water in any EPA region. The impact from the co-occurrence of arsenic 
and radon is not a concern on a national level because there was no 
significant co-occurring pairs in EPA Regions 1, 2, 3, 4, 7, 8, 9, and 
10. EPA requests comments on whether the NWIS database and this 
analysis is appropriate to use to represent co-

[[Page 38912]]

occurrence of arsenic with other constituents.

      Table V-9.--Correlation of Arsenic With Radon (Ground Water)
------------------------------------------------------------------------
                                                 Radon and
                         Arsenic types and       threshold    Frequency
    EPA  regions     threshold levels (g/L)                l)
------------------------------------------------------------------------
5 and 6............  Dissolved 25..  10010.  1005......  0100
                                                10010.....  0100
                                                100 Is the method sensitive enough to address the level of 
concern (i.e., the MCL)?
     Does the method give reliable analytical results at the 
MCL? What is the precision (or reproducibility) and the bias (accuracy 
or recovery)?
     Is the method specific? Does the method identify the 
contaminant of concern in the presence of potential interferences?
     Is the availability of certified laboratories, equipment 
and trained personnel sufficient to conduct compliance monitoring?
     Is the method rapid enough to permit routine use in 
compliance monitoring?
     What is the cost of the analysis to water supply systems?

C. What Analytical Methods and Method Updates Are Currently Approved 
for the Analysis of Arsenic in Drinking Water?

    EPA approved analytical methods and method updates for the analysis 
of arsenic in drinking water in previous rulemakings. EPA took the 
factors listed in section VI.B into consideration when it approved 
these methods and updates. The methods and updates, listed in Table VI-
1, are based on atomic absorption, atomic emission and mass 
spectroscopy methodologies and have been used for compliance monitoring 
of arsenic at the 0.05 mg/L MCL by State, Federal and private 
laboratories for many years. In this section on the discussion of 
analytical methods, and in the sections discussing the consumer 
confidence rule and public notification, EPA uses the mg/L units of 
measure, the units used in the regulatory language. Note that EPA's 
drinking water analytical methods refer to mg/L instead of g/
L, and milligrams are 1,000 times larger than micrograms.

             Table VI-1.--Approved Analytical Methods (and Method Updates) for Arsenic (CFR 141.23)
----------------------------------------------------------------------------------------------------------------
                                                                                                       MDL 2 or
                       Methodology                                    Reference method 1             EDL 3  (mg/
                                                                                                          L)
----------------------------------------------------------------------------------------------------------------
Inductively Coupled Plasma Atomic Emission Spectroscopy   200.7 (EPA)                                      0.008
 (ICP-AES).                                               3120B (SM)                                     3 0.050
Inductively Coupled Plasma Mass Spectroscopy (ICP-MS)     200.8 (EPA)                                     0.0014
 ICP-MS with Selective Ion Monitoring.                                                                4 (0.0001)
Stabilized Temperature Platform Graphite Furnace Atomic   200.9 (EPA)                                     0.0005
 Absorption (STP-GFAA) STP-GFAA with Multiple                                                         5 (0.0001)
 Depositions.
Graphite Furnace Atomic Absorption (GFAA)...............  3113B (SM)                                     3 0.001
                                                          D-2972-93C (ASTM)                              3 0.005
Gaseous Hydride Atomic Absorption (GHAA)................  3114B (SM)                                    3 0.0005
                                                          D-2972-93B (ASTM)                             3 0.001
----------------------------------------------------------------------------------------------------------------
1 The reference methods approved for measuring arsenic in drinking water are cited in 40 CFR 141.23. The
  reference methods include:
EPA = ``Methods for the Determination of Metals in Environmental Samples--Supplement I'', EPA/600/R-94-111, US
  EPA, May 1994. (US EPA, 1994b)

[[Page 38913]]

 
SM = Standard Methods for the Examination of Water and Wastewater, 18th and 19th eds., Washington, D.C., 1992
  and 1995. (APHA, 1992 and 1995 respectively). The 19th edition of SM was approved in the December 1, 1999
  final methods rule (64 FR 67450, US EPA 1999j).
ASTM = Annual Book of ASTM Standards: Waster and Environmental Technology,'' Vol. 11.01 and 11.02, American
  Society for Testing and Materials, 1994 and 1996. (ASTM, 1994 and 1996). The 1996 edition of ASTM was approved
  in the December 1, 1999 final methods rule (64 FR 67450, US EPA 1999j).
2 MDL = Method Detection Limit = ``the minimum concentration of a substance that can be measured and reported
  with 99% confidence that the analyte concentration is greater than zero.'' (40 CFR Part 136 Appendix B).
3 EDL = Estimated Detection Limit (EDL) is defined as either the MDL or a concentration of a compound in a
  sample yielding a peak in the final extract with a signal to noise ratio of 5, whichever value is greater.
  Although the ASTM GFAA method (D-2972-93C) has a reported EDL of 0.005 mg/L, this method is similar to other
  GFAA methods. EPA believes D-2972-93C is capable of detection limits similar to other GFAA methods.
4 In 1994 (59 FR 62456; US EPA, 1994c), the Agency approved the use of the updated ``Methods for the
  Determination of Metals in Environmental Samples--Supplement I,'' (US EPA, EPA/600/R-94/111, 1994). The
  revised manual allows the use of selective ion monitoring with ICP-MS. The determined MDL for the direct
  analysis of arsenic in aqueous samples was 0.1 g/L.
5 In 1994 (59 FR 62456; US EPA, 1994c), the Agency approved the use of the updated ``Methods for the
  Determination of Metals in Environmental Samples--Supplement I,'' (US EPA, EPA/600/R-94/111, 1994). The
  revised manual allows the use of multiple depositions with STP-GFAA. The determined MDL for arsenic using
  multiple deposition with STP-GFAA is 0.1 g/L.

D. Will Any of the Approved Methods for Arsenic Analysis Be Withdrawn?

    EPA believes all of the analytical methods listed in Table VI-1, 
with the exception of EPA Method 200.7 and SM 3120B, are technically 
and economically feasible for compliance monitoring of arsenic in 
drinking water at the proposed MCL of 0.005 mg/L. EPA is proposing to 
withdraw approval for EPA Method 200.7 and SM 3120B because the 
detection limit for the first ICP-AES method, 0.008 mg/L, and the 
estimated detection limit for the second ICP-AES method, 0.050 mg/L, 
are inadequate to reliably determine the presence of arsenic at the 
proposed MCL of 0.005 mg/L. Analysis of the Water Supply (WS) studies 
used to derive the PQL (Analytical Methods Support Document, US EPA, 
1999l) indicates that ICP-AES technology was rarely used for low level 
arsenic analysis. Therefore, the Agency believes the removal of the 
methods that use ICP-AES technologies will not have an impact on 
laboratory capacity.
    Even at the MCL options of 0.003, 0.010 mg/L, and 0.020 mg/L, the 
Agency would still withdraw both EPA Method 200.7 and SM 3120B. At 
these MCL options, these methods are still inadequate for compliance 
monitoring of arsenic in drinking water.

E. Will EPA Propose Any New Analytical Methods for Arsenic Analysis?

    The Agency conducted a literature search to identify additional 
analytical methods which are capable of compliance monitoring of 
arsenic at the proposed MCL of 0.005 mg/L (Analytical Methods Support 
Document, US EPA, 1999l). A large majority of the analytical techniques 
identified from the literature search were from EPA's Office of Solid 
Waste SW-846 methods manual, which can be accessed online at 
www.epa.gov/epaoswer/hazwaste/test/index.html. Of the Solid Waste 
methods, the Agency evaluated:
     SW-846 Method 6020 (ICP-MS, MDL = 0.0004 mg/L; US EPA, 
1994d);
     SW-846 Method 7060A (GFAA, MDL = 0.001 mg/L; US EPA, 
1994e);
     SW-846 Method 7062 (GFAA, MDL = 0.001 mg/L; US EPA, 
1994f);
     SW-846 Method 7063 (Anodic Stripping Voltammetry-ASV, MDL 
= 0.0001 mg/L; US EPA, 1996d);
    In addition to the SW-846 method, the Agency also reviewed:
     EPA Method 1632 (a wastewater GHAA method with an MDL = 
0.000002 mg/L or 0.002 g/L; US EPA 1996a); and
     EPA Method 200.15 (an ICP-AES with ultrasonic nebulization 
as part of the written method, MDL = 0.003 mg/L or 0.002 mg/L; US EPA, 
1994a).
    Although the SW-846 methods and the EPA 1632 wastewater method are 
capable of reaching the detection limits needed at the proposed arsenic 
MCL, most of these techniques (with the exception of the method using 
ASV technology) are similar to methods that have already been approved 
for the analysis of arsenic in drinking water. The Agency does not 
believe approval of these methods for drinking water would provide 
additional analytical benefits. Moreover, the addition of the SW-846 
methods could complicate the laboratory certification process because 
SW-846 methods are not mandatory procedures, but rather guidance. At 
this time, laboratories are certified at different times for different 
EPA programs. Therefore, laboratories certified for both drinking water 
methods and Office of Solid Waste methods may need to be certified 
separately under both programs to use SW-846 methods for drinking 
water.
    While SW-846 Method 7063 (using ASV technology) is not similar to 
any technique approved thus far, this method will not be approved for 
the measurement of arsenic in drinking water because it only detects 
dissolved arsenic as opposed to total arsenic. Today's proposal would 
regulate total arsenic in drinking water not dissolved arsenic. The 
techniques currently approved for drinking water measure total arsenic 
(arsenic species in the dissolved and suspended fractions of a water 
sample). A preliminary total metals digestion would be necessary with 
the ASV technique in order to determine the total arsenic concentration 
in a drinking water sample.
    The Agency also reviewed but does not propose to approve EPA Method 
200.15, an ICP-AES method which requires the use of ultrasonic 
nebulization to introduce the sample into the plasma. To provide 
uniform signal response using EPA Method 200.15, it is necessary for 
arsenic to be in the pentavalent state. The addition of hydrogen 
peroxide to the mixed acid solutions of samples and standards prior to 
ultrasonic nebulization is necessary to convert all of the arsenic 
species to the pentavalent state. Although EPA Method 200.15 is capable 
achieving a MDL of 0.003 mg/L using direct analysis and a MDL of 0.002 
mg/L using a total recoverable digestion and a 2-fold concentration, 
these levels of detection are still insufficient for compliance 
monitoring at the proposed MCL of 0.005 mg/L.
    At the MCL options of 0.010 mg/L and 0.020 mg/L, the Agency would 
approve the use of EPA Method 200.15 but only with the use of a total 
recoverable digestion and a 2-fold concentration (MDL = 0.002 mg/L). At 
an MCL option of 0.003 mg/L, EPA method 200.15 would not be approved.

F. Other Method-Related Items

1. The Use of Ultrasonic Nebulization with ICP-MS
    In the September 3, 1998 Analytical Methods for Drinking Water 
Contaminants Proposed Rule (63 FR 47907; US EPA 1998d), EPA proposed 
the use of ultrasonic nebulization with EPA Method 200.7 (ICP-AES) and 
EPA Method 200.8 (ICP-MS). Because EPA Method 200.7 and SM 3120B will 
be withdraw for the analysis of arsenic in drinking water under the 
proposed MCL of 0.005 mg/L, ultrasonic nebulization as a modification 
would not be allowed.

[[Page 38914]]

Even with the modification of ultrasonic nebulization, the ICP-AES 
method is not capable of compliance monitoring for arsenic at the 
proposed MCL of 0.005 mg/L. EPA Method 200.8 (ICP-MS) would still be 
allowed for compliance monitoring at the proposed MCL of 0.005 mg/L. 
The use of ultrasonic nebulization can enhance transport efficiency and 
lower the detection limits for ICP-MS by approximately 5 to 10 fold. 
The final methods update rule was published in the Federal Register on 
December 1, 1999 (64 FR 67450; US EPA 1999j).
2. Performance-Based Measurement System
    On October 6, 1997, EPA published a Notice of the Agency's intent 
to implement a Performance Based Measurement System (PBMS) in all of 
its programs to the extent feasible (62 FR 52098; US EPA, 1997e). EPA 
is currently determining how to adopt PBMS into its drinking water 
program, but has not yet made final decisions. When PBMS is adopted 
into the drinking water program, its intended purpose will be to 
increase flexibility in laboratories in selecting suitable analytical 
methods for compliance monitoring, significantly reducing the need for 
prior EPA approval of drinking water analytical methods. Under PBMS, 
EPA will modify the regulations that require exclusive use of Agency-
approved methods for compliance monitoring of regulated contaminants in 
drinking water regulatory programs. EPA will probably specify 
``performance standards'' for methods, which the Agency would derive 
from the existing approved methods and supporting documentation. A 
laboratory would be free to use any method or method variant for 
compliance monitoring that performed acceptably according to these 
criteria. EPA is currently evaluating which relevant performance 
characteristics under PBMS should be specified to ensure adequate data 
quality for drinking water compliance purposes. After PBMS is 
implemented, EPA may continue to approve and publish compliance methods 
for laboratories that choose not to use PBMS. After EPA makes final 
determinations about the implementation of PBMS in programs under the 
Safe Drinking Water Act, the Agency would then provide specific 
instruction on the specified performance criteria and how these 
criteria would be used by laboratories for compliance monitoring of 
SDWA analytes.

G. What Are the Estimated Costs of Analysis?

    To obtain cost information on the analysis of arsenic in drinking 
water, the Agency collected price information from a random telephone 
survey of seven commercial laboratories, which were certified in 
drinking water analysis, and from price lists posted on the Internet 
(Analytical Methods Support Document, US EPA, 1999l). Table VI-2 
summarizes the results of this survey, including the specific 
methodology and the associated cost range. The actual costs of 
performing an analysis may vary with laboratory, the analytical 
technique selected, and the total number of samples analyzed by a 
laboratory. The estimated cost range is only for the analysis of 
arsenic and does not include shipping and handling costs. The Agency 
solicits comments from the public on the cost estimates listed in Table 
VI-2.

  Table VI-2.--Estimated Costs for the Analysis of Arsenic in Drinking
                                Water \1\
------------------------------------------------------------------------
                                                   Estimated cost range
                   Methodology                              ($)
------------------------------------------------------------------------
Inductively Coupled Plasma Atomic Emission        15 to 25.
 Spectroscopy (ICP-AES).
Inductively Coupled Plasma Mass Spectroscopy      10 to 15.
 (ICP-MS).
Stabilized Temperature Platform Graphite Furnace  15 to 50.
 Atomic Absorption (STP-GFAA).
Graphite Furnace Atomic Absorption (GFAA).......  15 to 50.
Gaseous Hydride Atomic Absorption (GHAA)........  15 to 50.
------------------------------------------------------------------------
\1\ Analytical Methods Support Document (US EPA, 1999l).

H. What Is the Practical Quantitation Limit?

    Method detection limits (MDLs) and practical quantitation levels 
(PQLs) are two performance measures used by EPA's drinking water 
program to estimate the limits of performance of analytic chemistry 
methods for measuring contaminants in drinking water. As cited in Table 
VI-1, EPA defines the MDL as ``the minimum concentration of a substance 
that can be measured and reported with 99% confidence that the analyte 
concentration is greater than zero (40 CFR part 136, appendix B).'' 
MDLs can be operator, method, laboratory, and matrix specific. MDLs are 
not necessarily reproducible within a laboratory or between 
laboratories on a daily basis due to the day-to-day analytical 
variability that can occur and the difficulty of measuring an analyte 
at very low concentrations. In an effort to integrate this analytical 
chemistry data into regulation development, EPA's OGWDW uses the PQL to 
estimate or evaluate the minimum, reliable quantitation level that most 
laboratories can be expected to meet during day-to-day operations. 
EPA's Drinking Water program defined the PQL as ``the lowest 
concentration of an analyte that can be reliably measured within 
specified limits of precision and accuracy during routine laboratory 
operating conditions (50 FR 46906, November 13, 1985).''
1. PQL Determination
    A PQL is determined either through the use of interlaboratory 
studies or, in absence of sufficient information, through the use of a 
multiplier of 5 to 10 times the MDL. The inter-laboratory data is 
obtained from water supply (WS) performance evaluation (PE) studies 
that are conducted twice a year by EPA to certify drinking water 
laboratories (now referred to as the Performance Testing or PT 
program). In addition to certification of drinking water laboratories, 
WS studies also provide:
     Large-scale evaluation of analytical methods;
     A database for method validation;
     Demonstration of method utilization by a large number of 
laboratories; and
     Data for PQL determinations.

Using graphical or linear regression analysis of the WS data, the 
Agency sets a PQL at a concentration where at least 75% of the 
laboratories (generally EPA and State laboratories) could perform 
within an acceptable level of precision and accuracy. This method of 
deriving a PQL was used in the past for inorganics such as antimony, 
beryllium,

[[Page 38915]]

cyanide, nickel and thallium (57 FR 31776 at 31800; US EPA, 1992b).
2. PQL for Arsenic
    In 1994, EPA derived a preliminary PQL for arsenic based on data 
collected by the Agency from WS studies 20 through 33 (WS 31 was 
excluded because the spiked samples were mixed incorrectly). In 
response to concerns from the water utility industry, the results of 
this derivation and a separate evaluation conducted by the American 
Water Works Association (AWWA) were reviewed by the EPA Science 
Advisory Board (SAB) in 1995. The SAB noted that the acceptance limits 
of + 40% used by EPA to derive the PQL in 1994 were wider than those 
for other SDWA metal contaminants. The acceptance limits and PQLs for 
several SDWA metals are shown in Table VI-3. The SAB recommended that 
EPA set the PQL using acceptance limits similar to those used for other 
inorganics.

  Table VI-3.--Acceptance Limits and PQLs for Other Metals (in Order of
                             Decreasing PQL)
------------------------------------------------------------------------
                                                Acceptance
                 Contaminant                    limit \1\    PQL (mg/L)
                                                (percent)        \2\
------------------------------------------------------------------------
Barium.......................................  15
Chromium.....................................  15
Selenium.....................................  20
Antimony.....................................  30
Thallium.....................................  30
Cadmium......................................  20
Beryllium....................................  15
Mercury......................................  30
------------------------------------------------------------------------
\1\ Acceptance limits for the listed inorganics are found at CFR 141.23
  (k) (3)(ii).
\2\ The PQL for antimony, beryllium and thallium was published in 57 FR
  31776 at 31801 (July 17, 1992; US EPA, 1992b). The PQL for barium,
  cadmium, chromium, mercury and selenium was published in 66 FR 3526 at
  3459 (January 30, 1991; US EPA, 1991a).

    Subsequent to SAB's recommendation, EPA derived a new PQL for 
arsenic (Analytical Methods Support Document, US EPA, 1999l). The 
process employed by the Agency to determine the new PQL utilized:
     Data from six voluntary, low-level (0.006 mg/L of arsenic) 
WS studies;
     Acceptance limits similar to other low-level inorganics; 
and
     Linear regression analysis to determine the point at which 
75% of EPA Regional and State laboratories fell within the chosen 
acceptance range.
    The derivation of the PQL for arsenic was consistent with the 
process used to determine PQLs for other metal contaminants regulated 
under SDWA and took into consideration the recommendations from the 
SAB. Using acceptance limits of + 30% and linear regression analysis of 
WS studies 30 through 36 (excluding 31) yielded a PQL of 0.00258 mg/L. 
The Agency rounded up to derive a PQL for arsenic of 0.003 mg/L at the 
 30% acceptance limit. While the PQL represents a stringent 
target for laboratory performance, the Agency believes most 
laboratories, using appropriate quality assurance and quality control 
procedures, will achieve this level on a routine basis.

I. What Are the Sample Collection, Handling and Preservation 
Requirements for Arsenic?

    The manner in which samples are collected, handled and preserved is 
critical to obtaining valid data. Specific sample collection, handling 
and preservation procedures for SDWA analytes are outlined in the 
``Manual for the Certification of Laboratories Analyzing Drinking 
Water'' (US EPA, 1997a). For metals such as arsenic, the certification 
manual specifies the following:
     Nitric acid (HNO3 at pH 2) as the preservative;
     A maximum sample holding time of 6 months;
     And a sample size of 1 liter, collected in an 
appropriately cleaned plastic or glass container, is suggested.
    Currently, arsenic does not have an entry for preservation, 
collection, and holding time. EPA is proposing in this rule, to revise 
the table following Sec. 141.23(k)(2) to add ``arsenic, Conc. 
HNO3 to pH  2, P or G, and 6 months.'' EPA requests comment 
on the appropriateness of this revision.
    While 40 CFR 141.23(a)(4) allows compositing of up to 5 samples 
from the same PWS, the detection limit required for compositing must be 
\1/5\ of the MCL. Also, compositing for inorganic samples must be done 
in the laboratory. Samples should only be held if the laboratory 
detection limit is adequate for the number of samples being composited. 
In any case, the composite is not to exceed five samples. EPA is adding 
the test methods and detection limits for the approved arsenic 
analytical methods to the table following Sec. 141.23(a)(4)(i).

J. Laboratory Certification

1. Background
    The ultimate effectiveness of today's regulation depends upon the 
ability of laboratories to reliably analyze arsenic at the proposed 
MCL. The existing drinking water laboratory certification program 
(LCP), which was established by States with guidance and 
recommendations from EPA, requires that only certified laboratories 
analyze compliance samples. External checks of a laboratory's ability 
to analyze samples of regulated contaminants within specific limits is 
the one means of judging laboratory performance and determining whether 
or not to grant certification. Under a performance testing (PT) program 
(formerly known as the performance evaluation or PE program), 
laboratories are required to successfully analyze PT samples 
(contaminant concentrations are unknown to the laboratory being 
reviewed) that are prepared by appropriate third parties. Successful 
participation in a PT program is a prerequisite for a laboratory to 
achieve certification and to remain certified for analyzing drinking 
water compliance samples. Achieving acceptable performance in these 
studies of unknown test samples provides some indication that the 
laboratory is following proper practices. Unacceptable performance may 
be indicative of problems that could affect the reliability of the 
compliance monitoring data.
    2. What Are the Performance Testing Criteria for Arsenic?
    The Agency has historically identified acceptable performance using 
one of two different approaches:
    (a) Regressions from the performance of preselected laboratories 
(using 95 percent confidence limits), or

[[Page 38916]]

    (b) Specified accuracy requirements.
    Acceptance limits based on specified accuracy requirements are 
developed from past PE study data. EPA has traditionally preferred to 
use the second (``true value'') approach because it is the better 
indicator of performance and provides laboratories with a fixed target. 
Under this approach, each laboratory demonstrates its ability to 
perform within pre-defined limits. Laboratory performance is evaluated 
using a constant ``yardstick'' independent of performance achieved by 
other laboratories participating in the same study. A fixed criterion 
based on a percent error around the ``true'' value reflects the 
experience obtained from numerous laboratories and includes 
relationships of the accuracy and precision of the measurement to the 
concentration of the analyte. It also assumes little or no bias in the 
analytical methods that may result in average reporting values 
different from the reference ``true'' value.
    In today's rulemaking, the Agency is proposing that the laboratory 
certification criteria for arsenic be set at an acceptance limit of + 
30 % at > 0.003 mg/L in Sec. 141.23(k)(3)(ii). Analysis of water supply 
data indicate that laboratory capacity at this level should be 
sufficient for compliance monitoring. At this level, 75 % of EPA 
Regional and State laboratories and 62 % of non-EPA laboratories were 
capable of achieving acceptable results. As discussed in the Analytical 
Methods Support Document, (US EPA, 1999l), setting an acceptance limit 
of 20% would have decreased laboratory capacity. EPA 
requests comment on setting the acceptance limit at the upper range of 
SAB's recommendation.
    3. How Often is a Laboratory Required To Demonstrate Acceptable PT 
Performance?
    EPA requires that a PT (PE) sample for chemical contaminants be 
successfully analyzed at least once a year using each method which is 
used to report compliance monitoring results. For arsenic this would 
require that the laboratory successfully analyze a PT (PE) sample using 
the method which is used to report the results for compliance 
monitoring. Additional guidance on the minimum quality assurance 
requirements, conditions of laboratory inspections and other elements 
of laboratory certification requirements for laboratories conducting 
compliance monitoring measurements are detailed in the Manual for the 
Certification of Laboratories Analyzing Drinking Water, Criteria and 
Procedures Quality Assurance (US EPA, 1997a), which can be downloaded 
via the Internet at ``http://www.epa.gov/ogwdw000/certlab/
labindex.html.''
4. Externalization of the PT Program (Formerly Known as the PE Program)
    Due to resource limitations, on July 18, 1996 EPA proposed options 
for the externalization of the PT studies program (61 FR 37464; US EPA, 
1996c). After evaluating public comment, in the June 12, 1997 final 
notice EPA (62 FR 32112; US EPA, 1997c):

``decided on a program where EPA would issue standards for the 
operation of the program, the National Institute of Standards and 
Technology (NIST) would develop standards for private sector PE (PT) 
suppliers and would evaluate and accredit PE suppliers, and the 
private sector would develop and manufacture PE (PT) materials and 
conduct PE (PT) studies. In addition, as part of the program, the PE 
(PT) providers would report the results of the studies to the study 
participants and to those organizations that have responsibility for 
administering programs supported by the studies.''

EPA has addressed this topic in public stakeholders meetings and in 
some recent publications, including the Federal Register notices 
mentioned in this paragraph. More information about laboratory 
certification and PT (PE) externalization can be accessed at the OGWDW 
laboratory certification website under the drinking water standards 
heading (www.epa.gov/safewater).

VII. Monitoring and Reporting Requirements

    The currently applicable monitoring requirements for arsenic are 
different than the other inorganic contaminants (IOCs). First of all, 
arsenic's MCL and compliance requirements are found in Sec. 141.11, 
instead of in Sec. 141.62(b). Monitoring, compliance, and reporting 
requirements for arsenic are also different than the standardized 
monitoring framework for the grouped IOCs (which does not include 
radon). EPA is proposing to move arsenic to the standardized monitoring 
framework for IOCs (antimony, asbestos, barium, beryllium, cadmium, 
chromium, cyanide, fluoride, mercury, nickel, nitrate, nitrite, 
selenium, and thallium), including the State reporting and compliance 
requirements. Table VII-1 presents a comparison of the existing and 
proposed arsenic requirements, in abbreviated form. For a full picture 
of the regulations, you must look at the regulatory language.
    In addition, EPA is proposing to clarify the regulatory language 
for sampling to determine compliance for inorganics, volatiles and 
synthetic organic contaminants.

     Table VII-1.--Comparison of Sampling, Monitoring, and Reporting
                              Requirements
  [This table is not complete for compliance purposes, but provides an
                         overview for readers.]
------------------------------------------------------------------------
         Requirement              Current rule          Proposed rule
------------------------------------------------------------------------
Compliance with Sec.          MCL only applies to   Would link
 141.11(a).                    CWS and compliance    compliance with 50
                               is calculated using   g/L with
                               Sec.  141.23.         Sec.  141.23(l) and
                                                     would not add
                                                     NTNCWS.
Compliance with Sec.          MCL is 0.05 mg/L....  MCL will remain 50
 141.11(b).                                          g/L for
                                                     CWS serving 10,000
                                                     or less until 5
                                                     years after
                                                     publication of
                                                     final rule, and be
                                                     effective for
                                                     larger systems 3
                                                     years after
                                                     publication of
                                                     final rule. New
                                                     lower MCL in Sec.
                                                     141.62.
                                                    NTNCWS will be
                                                     subject to
                                                     sampling,
                                                     monitoring and
                                                     reporting 3 years
                                                     after publication
                                                     of final rule, but
                                                     not subject to
                                                     increased
                                                     monitoring after
                                                     exceedances, nor to
                                                     MCL violations.
Monitoring frequency........  Groundwater Sec.      No change to Sec.
                               141.23(a)(1) One      141.23(a)(1).
                               sample at each
                               entry point to the
                               distribution system
                               (sampling point).
                              Surface water Sec.    No change to Sec.
                               141.23(a)(2) One      141.23(a)(2).
                               sample at every
                               entry point to the
                               distribution system
                               (sampling point).

[[Page 38917]]

 
Compositing inorganics......  Sec.  141.23(a)(4)    Adding approved
                               may composite up to   arsenic analytical
                               5 samples in the      methods and
                               lab; detection        detection limits to
                               limit \1/5\ of the    the table following
                               MCL.                  Sec.  141.23(a)(4)(
                                                     i).
Composite >\1/5\ MCL........  Sec.  141.23(a)(4)(i  Same but Sec.
                               ) take follow-up      141.23(a)(4)(i)
                               samples within 14     table will list MCL
                               days of each          and detection
                               sampling point in     limits for arsenic.
                               the composite.
Compositing by system size..  Sec.  141.23(a)(4)(i  No change to Sec.
                               i) State may permit   141.23(a)(4)(ii).
                               compositing at
                               sampling points
                               within a system
                               serving >3,300
                               people.
                              Sec.  141.23(a)(4)(i  No change to Sec.
                               i) State may permit   141.23(a)(4)(ii).
                               compositing among
                               different systems,
                               5-sample limit,
                               systems serving
                               3,300 people.
Resampling composites.......  Sec.  141.23(a)(4)(i  No change to Sec.
                               ii) Can use           141.23(a)(4)(iii).
                               duplicates of the
                               original sample
                               instead, must be
                               analyzed and
                               reported to State
                               within 14 days of
                               collection.
Compliance with Sec.  141.11  Sec.  141.23(l)(1)    Sec.  141.23(c)(1)
 CWSs have same                CWS surface water     surface water one
 requirements, but arsenic     yearly.               sample per
 monitoring would move from                          compliance point
 Sec.  141.23(l) to Sec.                             annually.
 141.23(c).
                              Sec.  141.23(l)(2)    Sec.  141.23(c)(1)
                               CWS ground water      groundwater one
                               every three years..   sample at each
                                                     sampling point
                                                     during each
                                                     compliance period.
Monitoring waivers Sec.       None currently        Sec.  141.23(c)(2)
 141.23(c).                    available for         System may apply to
                               arsenic..             the State.
                                                    Sec.  141.23(c)(3)Mu
                                                     st take at least
                                                     one sample during
                                                     waiver, which
                                                     cannot exceed one
                                                     compliance period
                                                     (9 years).
Minimum data for waivers:     ....................  Sec.  141.23(c)(4)
 Surface water Ground water                          at least 3 years.
 All results MCL. New water                          At least 3 rounds
 source needs three rounds                           of monitoring. At
 of monitoring.                                      least one sample
                                                     must be taken after
                                                     January 1, 1990.
Once MCL exceeded sampling..  Sec.  141.23(m)       Sec.  141.23(c)(7)
                               Supplier must         exceed MCL as
                               report to State       calculated in (i),
                               within 7 days and     go to quarterly
                               initiate three        monitoring next
                               additional samples    quarter. Sec.
                               at the same           141.31(d) within 10
                               sampling point        days of giving
                               within a month.       public notice,
                                                     contact primacy
                                                     agency. Sec.
                                                     141.203(b) Tier 2
                                                     public notice no
                                                     later than 30 days
                                                     after learning of
                                                     violation and
                                                     repeat every 3
                                                     months or at least
                                                     once a year if
                                                     allowed by primacy
                                                     agency.
Compliance based on less      Not currently         Sec.  141.23(i)(1)
 than required number of       specified..           for IOCs, Sec.
 samples.                                            141.24(f)(15)(i)
                                                     for VOCs, and Secs.
                                                     141.24(h)(11)(i)
                                                     and (ii) for SOCs
                                                     will average based
                                                     on # samples
                                                     collected.
Average that determines       Sec.  141.23(n) When  Sec.  141.23(i)(5)
 violation..                   the 4 analyses,       arsenic will be
State notice................   rounded to the same   reported to the
Public notice...............   number of             nearest 0.001 mg/L.
                               significant figures   Sec.  141.23(i)(1)
                               as the MCL exceeds    monitoring >
                               the MCL, supplier     annually, running
                               must notify the       annual average at
                               State Sec.  141.31    sampling point. If
                               and give notice to    less samples taken
                               the public Sec.       than required,
                               141.32. Monitoring    compliance is based
                               frequency             on average of
                               determined by the     samples. Any sample
                               State must continue   below method
                               until  MCL in two     detection limit is
                               consecutive samples   assigned zero for
                               or until a            calculation.
                               variance,
                               exemption, or
                               enforcement action
                               schedule becomes
                               effective.
Sampling frequency after MCL    ..................  Sec.  141.23(i)(2)
 compliance monitoring begun.                        monitoring annually
                                                     or less often if
                                                     sampling point >
                                                     MCL.
Confirmation sample.........  None currently        If State requires a
                               specified for         confirmation
                               arsenic.              sample, then
                                                     compliance based on
                                                     average of the two
                                                     samples. If State
                                                     specifies
                                                     additional
                                                     monitoring,
                                                     compliance based on
                                                     running annual
                                                     average. If less
                                                     samples taken than
                                                     required,
                                                     compliance is based
                                                     on average of
                                                     samples.
Increased monitoring            ..................  Sec.  141.23(f)(1)
 frequency.                                          State may require
                                                     one within two
                                                     weeks.
                                                    Sec.  141.23(c)(8)
                                                     State can decrease
                                                     monitoring after a
                                                     minimum of 2
                                                     quarters for ground
                                                     water and 4
                                                     quarters for
                                                     surface water MCL.

[[Page 38918]]

 
                                                    Sec.  141.23(f)(1)
                                                     If >MCL, State can
                                                     require a
                                                     confirmation sample
                                                     within two weeks.
                                                     Sec.  141.23(f)(3)
                                                     Average used to
                                                     determine
                                                     compliance with
                                                     (i). States can
                                                     delete results with
                                                     obvious sampling
                                                     errors. Sec.
                                                     141.23(g) State may
                                                     require more
                                                     frequent
                                                     monitoring.
New system and new sources..  Only mentions waiver  Sec.  141.23(c)(9)
                               eligibility in Sec.   IOCs, Sec.
                                141.23(c)(4).        141.24(f)(22) VOCs,
                                                     Sec.  141.24(h)(20
                                                     SOCs, Compliance
                                                     demonstrated within
                                                     State-specified
                                                     time and sampling
                                                     frequencies.
Subpart O Consumer            >50 g/L      Lowers MCL & adds
 Confidence Reports for CWS.   annual report Sec.    MCLG to Appendices
                               141.153(d)(6)         A & B to Subpart O-
                               length of             effective 30 days
                               violation,            after final arsenic
                               potential health      rule is published,
                               effects using         before compliance
                               Appendix C, actions   with lower MCL is
                               taken. 25-50 g/L informational
                               statement per Sec.
                               141.154(b).
Subpart Q Public              >50 g/L      Sec.  141.203(b)
 Notification for PWS.         CWSs Tier 2 annual    Tier 2 public
                               report Sec.           notice no later
                               141.203 required      than 30 days after
                               October 31, 2000      learning of
                               (if they are in       violation and
                               jurisdictions where   repeat every 3
                               the program is        months or at least
                               directly              once a year if
                               implemented by EPA)   allowed by primacy
                               or on the date a      agency.
                               primacy State
                               adopts the new
                               requirements (not
                               to exceed May 6,
                               2002)..
                                                    Sec.  141.31(d)
                                                     within 10 days of
                                                     giving public
                                                     notice, contact
                                                     primacy agency.
                                                    >5 g/L CWSs
                                                     & add NTNCWS to
                                                     Table 1 of Sec.
                                                     141.203 to require
                                                     Tier 2 annual
                                                     report Sec.
                                                     141.203 after
                                                     effective date of
                                                     arsenic MCL (3-5
                                                     yrs).
------------------------------------------------------------------------

A. What Are the Existing Monitoring and Compliance Requirements?

    The arsenic monitoring requirements appear in 40 CFR 141.23(a). 
Surface water systems must collect routine samples annually and ground 
water systems must collect a routine sample every three years. However, 
Sec. 141.11(a) currently only requires community water systems (CWS) to 
monitor for arsenic. EPA understands that some States also require 
their non-transient non-community water systems (NTNCWS) to collect 
samples for the analysis of arsenic as well. Under the proposal, CWSs 
would continue to be allowed to composite samples as specified in 
Sec. 141.23(a)(3); however, the one-fifth arsenic MCL will no longer be 
10 g/L (It will be 1 g/L).
    Sections 141.23(l) through (q) are currently used to determine 
compliance for arsenic. That is, if arsenic is detected at a 
concentration greater than the maximum contaminant level (MCL), the 
community water system must collect 3 additional samples within one 
month at the entry point to the distribution system that exceeded the 
MCL (Sec. 141.23(n)). If the average of the four analyses performed, 
rounded to one significant figure, exceeds the MCL, the system must 
notify the State; and the system must provide public notice 
(Sec. 141.23(n)). After public notification, the monitoring continues 
at the frequency designated by the State until the MCL ``has not been 
exceeded in two successive samples or until [the State establishes] a 
monitoring schedule as a condition to a variance, exemption or 
enforcement action (Sec. 141.23(n)).'' Monitoring waivers are not 
permitted to exclude a system from the sampling requirements under 
Sec. 141.23(l)-(q) which currently apply to arsenic.

B. How Does the Agency Plan To Revise the Monitoring Requirements?

    The Agency is proposing to require CWS and NTNCWSs to monitor for 
arsenic using Sec. 141.23(c). This will make the arsenic monitoring 
requirements consistent with the inorganic contaminants (IOC's) 
regulated under the standardized monitoring framework. EPA is proposing 
that NTNCWSs monitor and report arsenic results to the State and 
public, as a Tier 2 notice in subpart Q, Public Notification. However, 
the Agency is proposing that NTNCWSs not be required to meet the MCL, 
unlike the other inorganics listed in Sec. 141.62(b). EPA's analysis 
for not requiring NTNCWSs to comply with the MCL is based on the cost-
benefit analysis discussed later in section XI.C. of this preamble.
    If arsenic exceeds the MCL, the CWS will be triggered into 
quarterly monitoring for that sampling point ``in the next quarter 
after the violation occurred (Sec. 141.23(c)(7).'' The State may allow 
the system to return to the routine monitoring frequency when the State 
determines that the system is reliably and consistently below the MCL. 
However, the State cannot make a determination that the system is 
reliably and consistently below the MCL until a minimum of 2 
consecutive ground water or 4 consecutive surface water samples have 
been collected (Sec. 141.23(c)(8)). All systems must comply with the 
sampling requirements, unless a waiver has been granted in writing by 
the State (Sec. 141.23(c)(6)).
    As shown in Table VI-1, the approved methods can measure to 0.001 
mg/L or below. In order to use the analytical power of the methods, EPA 
is proposing that arsenic data be reported to the nearest 0.001 mg/L. 
Therefore, a result of 0.0055 mg/L would be rounded to 0.006 mg/L, and 
0.0145 mg/L would be rounded to 0.014 mg/L (Figures ending in ``5'' 
rounded down to end on an even digit and up to an even digit.). During 
the writing of this regulation, some people had asked whether data 
above 0.01 mg/L could be rounded to one significant figure because the 
MCL is being proposed with one significant figure. EPA is issuing a 
clarification to arsenic reporting in Sec. 141.23(i) to indicate that 
arsenic results will be reported to the nearest 0.001 mg/L. The 
significance for compliance purposes will be that values between 0.010 
mg/

[[Page 38919]]

L and 0.014 mg/L will be averaged to the nearest 0.001 mg/L, and the 
yearly average will more closely reflect the values measured. EPA 
requests comment on these clarifications to reporting requirements.

C. Can States Grant Monitoring Waivers?

    As proposed, States will be able to grant a 9-year monitoring 
waiver to a system (Sec. 141.23(c)(3)). Waivers of arsenic sampling 
requirements must be based on all analytical results from previous 
sampling and a vulnerability assessment or the assessment from an 
approved source water assessment program (provided that the assessments 
were designed to collect all of the necessary information needed to 
complete a vulnerability assessment for a waiver). States issuing 
waivers must consider the requirements in 40 CFR 141.23(c)(2)-(6). In 
order to qualify for a waiver, there must be three previous samples 
from a sampling point (annual for surface water and three rounds for 
groundwater) with analytical results reported below the proposed MCL 
(i.e., the reporting limit must be  0.005 mg/L). The use of 
grandfathered data collected after January 1, 1990 that is consistent 
with the analytical methodology and detection limits of the proposed 
regulation may be used for issuing sampling point waivers. The existing 
Sec. 141.23(l)-(q) regulations do not permit the use of monitoring 
waivers. However, a State could now use the analytical results from the 
three previous compliance periods (1993-1995, 1996-1998, and 1999-2001) 
to issue ground water sampling point waivers. Surface water systems 
must collect annual samples so a State could use the previous 3 years 
sampling data (1999, 2000, and 2001) to issue sampling point waivers. 
One sample must be collected during the nine-year compliance cycle that 
the waiver is effective, and the waiver must be renewed every nine 
years. Vulnerability assessments must be based on a determination that 
the water system is not susceptible to contamination and arsenic is not 
a result of human activity (i.e., it is naturally occurring).
    Although the approved analytical methods can measure to 0.005 mg/L, 
not all States have required systems to report arsenic results below 50 
g/L. In this case, the States would not have adequate data to 
grant waivers until enough data are available to make the 
determinations. EPA has compliance monitoring data from 25 States at 10 
g/L and below. On the other hand, one State submitted data to 
EPA rounded to tens of g/L, so some States may not be able to 
grant waivers until the data are reported below the proposed MCL.
    EPA believes that some States may have been regulating arsenic 
under the standardized inorganic framework being proposed today. If so, 
those States will have to ensure that existing monitoring waivers have 
been granted using data reported below the new proposed MCL. Otherwise 
States will have to notify the systems of the new lower reporting 
requirements that need to be met to qualify for a waiver for the 
proposed MCL.

D. How Can I Determine if I Have an MCL Violation?

    For this proposal, violations of the arsenic MCL would be 
determined under Sec. 141.23(f)-(i). If a system samples more 
frequently than annually (e.g., quarterly), the system would be in 
violation if the running annual average at any sampling point exceeds 
the MCL or if any one sample would cause the annual average to be 
exceeded (Sec. 141.23(i)(1)). If a system conducts sampling at an 
annual or less frequent basis, the system would be in violation if one 
sample (or the average of the initial and State-required confirmation 
sample(s)), at any sampling point exceeds the MCL (Sec. 141.23(i)(2). 
However, States can require more frequent monitoring per Sec. 141.23(g) 
for systems sampling annually or less often. Therefore, the Agency is 
proposing to clarify this section for situations for IOCs in 
Sec. 141.23(i)(2)) and the corresponding sections for volatile and 
synthetic organic contaminants (Secs. 141.24(f)(15)(ii) and 
141.24(h)(11)(ii), respectively. This proposal clarifies compliance for 
contaminants subject to Secs. 141.23(i)(2)), 141.24(f)(15)(ii), and 
141.24(h)(11)(ii) by pointing out that compliance will be based on the 
running annual average of the initial MCL exceedance and subsequent 
State-required confirmation samples. These confirmation samples may be 
required at State-specified frequencies (e.g., quarterly or some other 
frequency depending on site-specific conditions).
    In addition, the clarifications to Secs. 141.23(i)(2)), 
(141.24(f)(15)(ii) and 141.24(h)(11)(ii) address calculation of 
compliance when a system fails to collect the required number of 
samples. Compliance (determined by the average concentration) would be 
based on the total number of samples collected. The Agency expects 
systems will conduct all required monitoring. However, some systems 
have purposely not collected the required number of quarterly samples, 
and in doing so some avoided reporting an MCL violation. While these 
systems all incurred monitoring and reporting violations for the 
uncollected samples, some systems divided the sum of the samples taken 
by four, which lowered the annual average reported to below the MCL, 
avoiding an MCL violation. The Agency requests comment on this 
clarification of exceedances determined under a State-determined 
monitoring frequency.
    For purposes of calculating MCL annual averages, Sec. 141.23(i)(1) 
continues to set all non-detects equal to a value of zero. However, the 
Agency realizes that some States use the detection limit or a fraction 
of the detection limit to calculate an average.

E. When Will Systems Have To Complete Initial Monitoring?

    The rule becomes effective 3 years after promulgation (about 
January 1, 2004) for large PWS (serving over 10,000). This will require 
all GW and SW systems serving over 10,000 to complete the initial round 
of monitoring by December 31, 2004. However, States may allow systems, 
on a case-by-case basis, 2 additional years to comply with the MCL if 
capital improvements are necessary.
    The Agency is proposing a national finding that capital 
improvements are necessary for public water systems serving less than 
10,000, on the basis that existing treatments are not expected to be 
effective in arsenic removal. Table VII-2 shows the percentage of small 
systems with no treatment in place as well as the percentage of systems 
which currently have in place technologies that can remove arsenic. The 
data shows that capital improvements would be necessary for many 
systems. The rule would be effective 5 years after promulgation (about 
January 1, 2006) for systems serving under 10,000. This would require 
these small GW systems to complete the initial round of monitoring by 
the December 31, 2007 ('05-'07 compliance period), and small SW systems 
to complete the initial round of monitoring by December 31, 2006. EPA 
is requesting comment on whether it is appropriate to make a national 
finding that systems serving less than 10,000 people will need the two 
additional years to add capital improvements in order to comply with 
the proposed MCL. The alternative would require States to issue 
individual two-year extensions for these small systems.

[[Page 38920]]



                                Table VII-2.--Treatment In-Place at Small Water Systems (US EPA, 1999e and US EPA, 1999m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   Percent of        Percent of        Percent of        Percent of        Percent of
                                                                 systems with no  systems with ion    systems with      systems with      systems with
                                                                  treatment in       exchange in      coagulation/     lime softening    reverse osmosis
                          System size                                 place             place         filtration in       in place          in place
                                                               ------------------------------------       place      -----------------------------------
                                                                                                   ------------------
                                                                   GW       SW       GW       SW       GW       SW       GW       SW       GW       SW
--------------------------------------------------------------------------------------------------------------------------------------------------------
25-100........................................................       50        7      1.7        0      1.7     21.7      2.6      4.3        0        0
101-500.......................................................       25        6      1.4        0      4.1     53.3      2.7      8.9      0.5        0
501-1K........................................................       25        0      2.9        0      2.4     73.0      2.4     18.9        0        0
1K-3.3K.......................................................       27        0      1.6        0      2.7     76.4      2.7     16.4      0.4        0
3.3K-10K......................................................       26        0      2.1        0      8.1     85.3      3.3      7.4      0.6       0
--------------------------------------------------------------------------------------------------------------------------------------------------------
References: Geometries and Characteristics of Public Water Systems, August 1999, (US EPA, 1999e) Drinking Water Baseline Handbook, February 24,1999, (US
  EPA, 1999m)

    The regulatory changes affected by the revised arsenic MCL are 
summarized in Table VII-3.

           Table VII-3.--Table Identifying Regulatory Changes
------------------------------------------------------------------------
         CFR citation                       Topic or subpart
------------------------------------------------------------------------
Sec.  141.23(a)(4)...........  Sample compositing allowed by the State.
141.23(a)(4)(i)..............  Detection limit for arsenic.
141.23(a)(5).................  Frequency of monitoring for arsenic
                                determined in Sec.  141.23(c).
141.23(c)....................  Standard inorganic monitoring framework,
                                with State waivers possible.
141.23(f)(1).................  Confirmation sampling may be required by
                                the State.
141.23(g)....................  More frequent monitoring may be required
                                by the State.
141.23(i)(5).................  Compliance determination reporting.
141.23(k)(1).................  Approved methodology.
141.23(k)(2).................  Container, preservation, and holding
                                time.
141.23(k)(3)(ii).............  Acceptance limit for certified
                                laboratories.
141.62(b)(16)................  MCL for arsenic.
141.62(c)....................  BATs for arsenic.
141.26(d)....................  Small system compliance technologies
                                (SSCTs).
141.154(b)...................  Requires CWS to report exceedances of new
                                MCL in CCR before lower MCL is
                                effective, removing 25-50 g/L
                                informational statement requirement.
Appendix A to Subpart O of     Converting lower MCL compliance values
 141.                           for CCRs and listing MCLG.
Appendix B to Subpart O of     Changes MCLG and MCL values effective 30
 141.                           days after MCL is final.
PN, Subpart Q, Table 1 to      Add NTNCWS exceeding MCL (not a
 Sec.  141.203.                 violation) to Tier 2 reporting.
Appendix A to Subpart Q of     Public notification regulatory citations
 141.                           revised.
Appendix B to Subpart Q of     Standard Health Effects Language
 141.                           unchanged; revise MCLG, MCL.
------------------------------------------------------------------------

    In order to prevent the arsenic MCL of 5 g/L from becoming 
effective immediately, EPA is proposing to delete the reference to 
Sec. 141.11(a) in Sec. 141.6(c), which provides effective dates. While 
examining Sec. 141.6(c) for sections that affect arsenic, we found 
several sections that do not exist. Therefore, EPA is proposing to 
remove the reference to the following sections in Sec. 141.6(c) listed 
in Table VII-4:

              Table VII-4.--Table Listing Deleted Sections
------------------------------------------------------------------------
              CFR section                        Topic or reason
------------------------------------------------------------------------
141.11(a)..............................  New arsenic MCL would be
                                          effective immediately.
141.11(e)..............................  Section 141.11(e) does not
                                          exist
141.14(a)(1)...........................  Section 141.14 does not exist.
141.14(b)(1)(i)........................  Section 141.14 does not exist.
141.14(b)(2)(i)........................  Section 141.14 does not exist.
141.14(d)..............................  Section 141.14 does not exist.
141.24(a)(3)...........................  Section 141.24(a) is reserved.
------------------------------------------------------------------------

    The Agency requests comment on whether these deletions to 
Sec. 141.6(c) are necessary and appropriate.

F. Can I use Grandfathered Data To Satisfy the Initial Monitoring 
Requirement?

    Ground water systems may use grandfathered data collected after Jan 
1, 2002 to satisfy the sampling requirements for the 2002--2004 
compliance period. However, the detection limit must be less than the 
revised MCL. If the grandfathered data is used to comply with the 2002-
2004 compliance period and the analytical result is between the current 
MCL and the revised MCL, then that system will be in violation of the 
revised MCL on the effective date of the rule. If the system chooses 
not to use the grandfathered data, then it must collect another sample 
by December 31, 2004 to demonstrate compliance with the revised MCL.

[[Page 38921]]

G. What Are the Monitoring Requirements for New Systems and Sources?

    The current regulations only address new systems and sources in the 
waiver provisions of Sec. 141.23(c)(4), so the proposal specifically 
adds monitoring requirements for these systems for inorganic, volatile 
organic, and synthetic organics contaminants. All new systems or 
systems that use a new source of water that begin operation after the 
effective date of this rule would have to demonstrate compliance with 
the MCL within a period of time specified by the State. The State would 
also specify sampling frequencies to ensure a system can demonstrate 
compliance with the MCL. This requirement would be effective for all 
inorganic, volatile organic, and synthetic organic contaminants 
regulated in Sec. 141.23 and Sec. 141.24. The Agency recognizes that 
many States have established requirements for new systems and new 
sources, and these are part of the approved State primacy programs. 
Therefore EPA believes that recognizing State-determined compliance 
will be the most effective way to regulate new systems and sources. EPA 
requests comment on this proposed clarification.

H. How Does the Consumer Confidence Report Change?

    On August 19, 1998, EPA issued subpart O, the final rule requiring 
community water systems to provide annual reports on the quality of 
water delivered to their customers (63 FR 44512; US EPA, 1998e). The 
first Consumer Confidence Reports (CCRs) were required by October 19, 
1999. The next reports are due by July 1, 2000, for calendar year 1999 
data and every July 1 after that (Sec. 141.152(a)). In general, reports 
must include information on the health effects of contaminants only if 
there has been a violation of an MCL or a treatment technique. For such 
violations specific ``health effects language'' in subpart O must be 
included verbatim in the report. The arsenic health effects language is 
currently required when arsenic levels exceed 50 g/L.
    In addition, the Agency decided to require more information for 
certain contaminants because of concerns raised by commenters. One of 
these contaminants was arsenic. As explained in the preamble to the 
final rule (63 FR 44512 at 44514; US EPA, 1998e) because of concerns 
about the adequacy of the current MCL, EPA decided that systems that 
detect arsenic between 0.025mg/L and the current MCL must include some 
information regarding arsenic (Sec. 141.154(b)). This informational 
statement is different from the health effects language required for an 
exceedance of the MCL. EPA noted that the requirement would be deleted 
upon promulgation of a revised MCL.
    Another issue which affects handling of arsenic in the CCR is the 
provision in the statute which authorized the Administrator to require 
inclusion of language describing health concerns for ``not more than 
three regulated contaminants'' other than those detected at levels 
which constitute a violation of an MCL (section 1414(c)(4)(B)(vi)). 
Based on stakeholder and commenter input, the Agency decided in the 
final CCR rule that it would use this authority in future rulemaking to 
require health effects language when certain MCLs are promulgated or 
revised. The health effects language of Subpart O would have to be 
included in reports of systems detecting a contaminant above the level 
of the new or revised MCL, prior to the effective date of the MCL, 
although technically the systems are not in violation of the 
regulations. The Agency used this authority in the promulgation of the 
Disinfectants and Disinfection Byproducts for one contaminant, Total 
Trihalomethanes on December 16, 1998 (63 FR 69390). The Agency is now 
proposing to use this same authority to require inclusion of the health 
effects language in reports of systems which detect arsenic above the 
level of the revised MCL upon promulgation of these regulations. The 
Agency believes that it is important to provide this information to 
customers immediately. The systems have the flexibility to place this 
information in context and explain to customers that there is no on-
going violation. Furthermore, the health advisory EPA is planning to 
issue in the near future will provide consumers with information about 
obtaining sources with lower arsenic prior to the effective date of the 
5 g/L arsenic MCL. EPA asks for comment on whether the 
consumer confidence report should notify customers of arsenic health 
effects starting with the report issued by July 1, 2002 for calendar 
year 2001.
    After the promulgation date of the revised arsenic MCL and before 
the effective date, community water systems that detect arsenic above 5 
g/L but below 50 g/L would include the arsenic health 
effects language. Those systems that detect arsenic above 50 
g/L would include the health effects language and also report 
violations as required by Sec. 141.153(d)(6).

I. How Will Public Notification Change?

    On May 4, 2000, EPA issued the final Public Notification Rule (PNR) 
for Subpart Q (US EPA 2000c) to revise the minimum requirements public 
water systems must meet for public notification of violations of EPA's 
drinking water standards and other situations that pose a risk to 
public health from the drinking water. Water systems must begin to 
comply with the new PNR regulations on October 31, 2000 (if they are in 
jurisdictions where the program is directly implemented by EPA) or on 
the date a primacy State adopts the new requirements (not to exceed May 
6, 2002). EPA's arsenic drinking water regulation affects public 
notification requirements and amends the PNR as part of its rulemaking.
    The PNR divides the public notice requirements into three tiers, 
based on the seriousness of the violation or situation. Tier 1 is for 
violations and situations with significant potential to have serious 
adverse effects on human health as a result of short-term exposure. 
Notice is required within 24 hours of the violation. Tier 2 is for 
other violations and situations with potential to have serious adverse 
effects on human health. Notice is required within 30 days, with 
extensions up to three months at the discretion of the State or primacy 
agency. Tier 3 is for all other violations and situations requiring a 
public notice not included in Tier 1 and Tier 2. Notice is required 
within 12 months of the violation, and may be included in the consumer 
confidence report at the option of the water system.
    Today's proposal will require community water systems (CWS) to 
provide a Tier 2 public notice for arsenic MCL violations and to 
provide a tier 3 public notice for violations of the monitoring and 
testing procedure requirements. Today's proposal would also require 
NTNCWS to provide a Tier 2 notice for exceedances of the MCL. As later 
explained in section XI.C., the Agency believes that overall risks from 
water ingested from NTNCWS cannot justify the costs of treatment. EPA 
believes that most States will, using their authority as described in 
Sec. 141.203(b), require NTNCWS to issue repeat notices on a yearly 
basis rather than every three months. EPA requests comment on the 
implementation of arsenic public notification requirements by the 
effective date of the arsenic MCL and on the Tier 2 public notice 
requirement for quarterly repeat notices for continuing exceedances of 
the arsenic MCL for NTNCWS.

[[Page 38922]]

VIII. Treatment Technologies

    Section 1412(b)(4)(E) of the Safe Drinking Water Act states that 
each NPDWR which establishes an MCL shall list the technology, 
treatment techniques, and other means which the Administrator finds to 
be feasible for purposes of meeting the MCL. Technologies are judged to 
be a best available technology (BAT) when the following criteria are 
satisfactorily met:
     The capability of a high removal efficiency;
     A history of full scale operation;
     General geographic applicability;
     Reasonable cost;
     Reasonable service life;
     Compatibility with other water treatment processes; and
     The ability to bring all of the water in a system into 
compliance.
    In order to fulfill this requirement set forth by SDWA, EPA has 
identified BATs in Section VIII.A. Their removal efficiencies and a 
brief discussion of the major issues surrounding the usage of each 
technology are also given in section VIII.A. Likely treatment trains, 
of which the BAT will be the integral part, are identified in section 
VIII. B. The costs associated with these treatment trains are also 
provided. More details about the treatment technologies and costs can 
be found in ``Technologies and Costs for the Removal of Arsenic From 
Drinking Water'' (US EPA,1999i).
    Section 1412(b)(4)(E)(ii) of the Act also states that EPA shall 
list any affordable small systems compliance technologies that are 
feasible for the purposes of meeting the MCL. The general process by 
which EPA identifies compliance, and if necessary, variance 
technologies is described in section VIII.C. The Agency, for the 
revised arsenic regulation, is not proposing any variance technologies. 
Compliance technologies for arsenic are identified in section VIII.E. 
More details about the technologies and affordability determinations 
can be found in ``Compliance Technologies for Arsenic'' (US EPA,1999g).
    Section VIII.F briefly discusses how other rules, presently being 
developed by the Agency, may impact the arsenic rule, or how the 
arsenic rule may impact these other regulations.

A. What Are the Best Available Technologies (BATs) for Arsenic? What 
Are the Issues Associated With These Technologies?

    EPA reviewed several technologies as BAT candidates for arsenic 
removal: ion exchange, activated alumina, reverse osmosis, 
nanofiltration, electrodialysis reversal, coagulation assisted 
microfiltration, modified coagulation/filtration, modified lime 
softening, greensand filtration, conventional iron and manganese 
removal, and several emerging technologies. The Agency proposes that, 
of the technologies capable of removing arsenic from source water, only 
the technologies in Table VIII-1 fulfill the requirements of the SDWA 
for BAT determinations for arsenic. The maximum percent removal that 
can be reasonably obtained from these technologies is also shown in the 
table. These removal efficiencies are for arsenic (V) removal.

      Table VIII-1.--Best Available Technologies and Removal Rates
------------------------------------------------------------------------
                                                                Maximum
                     Treatment technology                       percent
                                                               removal 1
------------------------------------------------------------------------
Ion Exchange.................................................         95
Activated Alumina............................................         90
Reverse Osmosis..............................................        >95
Modified Coagulation/Filtration..............................         95
Modified Lime Softening......................................         80
Electrodialysis Reversal.....................................        85
------------------------------------------------------------------------
\1\ The percent removal figures are for arsenic (V) removal.

    In water, the most common valence states of arsenic are As (V), or 
arsenate, and As (III), or arsenite. As (V) is more prevalent in 
aerobic surface waters and As (III) is more likely to occur in 
anaerobic ground waters. In the pH range of 4 to 10, As (V) species 
(H2AsO4-and 
H2AsO42-) are negatively charged, and 
the predominant As (III) compound (H3AsO3) is 
neutral in charge. Removal efficiencies for As (V) are much better than 
removal of As (III) by any of the technologies evaluated, because the 
arsenate species carry a negative charge and arsenite is neutral under 
these pH conditions. To increase the removal efficiency when As (III) 
is present, pre-oxidation to the As (V) species is necessary.
    Pre-oxidation. As (III) may be converted through pre-oxidation to 
As (V) using one of several oxidants. Data on oxidants indicate that 
chlorine, potassium permanganate, and ozone are effective in oxidizing 
As (III) to As (V). Pre-oxidation with chlorine may create undesirable 
concentrations of disinfection by-products and membrane fouling of 
subsequent treatments such as reverse osmosis. EPA has completed 
research on the chemical oxidants for As (III) conversion, and is 
presently investigating ultraviolet light disinfection technology (UV) 
and solid oxidizing media. For point-of-use and point-of-entry (POU/
POE) devices, central chlorination may be required for oxidation of As 
(III).
    Coagulation/Filtration (C/F) is an effective treatment process for 
removal of As (V) according to laboratory and pilot-plant tests. The 
type of coagulant and dosage used affects the efficiency of the 
process. Within either high or low pH ranges, the efficiency of C/F is 
significantly reduced. Below a pH of approximately 7, removals with 
alum or ferric sulfate/chloride are similar. Above a pH of 7, removals 
with alum decrease dramatically (at a pH of 7.8, alum removal 
efficiency is about 40%). Other coagulants are also less effective than 
ferric sulfate/chloride. Disposal of the arsenic-contaminated 
coagulation sludge may be a concern especially if nearby landfills are 
unwilling to accept such a sludge.
    Lime Softening (LS), operated within the optimum pH range of 
greater than 10.5 is likely to provide a high percentage of As removal. 
However, if removals greater than 80% are required, it may be difficult 
to remove consistently at that level by LS alone. Systems using LS may 
require secondary treatment to meet that goal (e.g., addition of an ion 
exchange unit as a polishing step). As with C/F, disposal of arsenic-
contaminated sludge from LS may be an issue.
    Coagulation/Filtration and Lime Softening are technologies 
primarily used for large systems. Package plants may make it more 
affordable for small systems to employ these technologies. Package 
plants are pre-engineered (i.e., the process engineering for the 
package plants has been done by the manufacturer). What remains for the 
water system's engineer to design is the specifics of the on-site 
application of the equipment. However, these technologies still require 
well trained operators. If it is not possible to keep a trained 
operator at the plant, an off-site contract operator may be able to 
monitor the process with a telemetry device. Because of these 
complexities, these technologies are not likely to be installed solely 
for arsenic removal. However, if they are already in place, 
modification of these two technologies to achieve higher arsenic 
removal efficiencies is a viable option.
    Activated Alumina (AA) is effective in treating water with high 
total dissolved solids (TDS). However, the capacity of activated 
alumina to remove arsenic is very pH sensitive. High removals can be 
achieved at high pHs, but at shorter run lengths. The use of chemicals 
for pH adjustment and bed regeneration, storage of sulfuric acid and 
sodium hydroxide, and process oversight increase operator 
responsibilities and the need for advanced training. (Decisions on the 
certification of water operators will be

[[Page 38923]]

made at the State and local levels). Operators may have to add an acid 
to lower pH to an optimal range and then afterwards increase the pH to 
avoid corrosion. Sodium hydroxide and sulfuric acid are required in the 
regeneration process. Selenium, fluoride, chloride, sulfate, and 
silica, if present at high levels, may compete for adsorption sites. 
Suspended solids and precipitated iron can cause clogging of the AA 
bed. Systems containing high levels of these constituents may require 
pretreatment or periodic backwashing. AA is highly selective towards As 
(V), and this strong attraction results in regeneration problems, 
possibly resulting in 5 to 10 percent loss of adsorptive capacity after 
each run. As a result, AA may not be efficient in the long term. In 
addition, activated alumina produces highly concentrated waste streams, 
which can contain approximately 30,000 mg/L of total dissolved solids 
(TDS) content. Because of the high content of TDS in the waste stream, 
disposal of the brine must be taken into consideration.
    The safety issue of handling corrosive and caustic chemicals 
associated with this technology may make it inappropriate for small 
systems. Therefore, in estimating national costs, it was assumed that 
small systems would not adjust pH and would not regenerate on site. 
Costs were estimated assuming systems operated a non-optimal pH and 
operation on a ``throw-away'' basis. Regenerating the media off-site 
instead of disposing of spent media is another possibility.
    Ion Exchange (IX) can effectively remove arsenic as well. It is 
recommended as a BAT primarily for small, ground water systems with low 
sulfate and TDS, and as a polishing step after filtration. Sulfate, 
TDS, selenium, fluoride, and nitrate compete with arsenic for binding 
sites and can affect run length. Column bed regeneration frequency is a 
key factor in calculating costs. Recent research indicates that ion 
exchange may be practical up to approximately 120 mg/L of sulfate 
(Clifford 1994). Passage through a series of columns could improve 
removal and decrease regeneration frequency. As with AA, suspended 
solids and precipitated iron can cause clogging of the IX bed. Systems 
containing high levels of these constituents may require pretreatment. 
Suspended solids and precipitated iron may also be removed by 
backwashing.
    Ion exchange also produces a highly concentrated waste by-product 
stream, and the disposal of this brine must be considered. Brine 
recycling can reduce the amount of waste for disposal and lower the 
cost of operation. Recent research showed that the brine regeneration 
solution could be reused as many as 20 times with no impact on arsenic 
removal provided that some salt was added to the solution to provide 
adequate chloride levels for regeneration (Clifford 1998).
    Reverse Osmosis (RO) can provide removal efficiencies of greater 
than 95 percent when operating pressure is ideal (e.g., pounds per 
square inch, psi). Water rejection (on the order of 20-25%) may be an 
issue in water-scarce regions. If RO is used by small systems in the 
western U. S., water recovery will likely need to be optimized due to 
the scarcity of water resources. Water recovery is the volume of water 
produced by the process divided by the influent stream (product water/
influent stream). Increased water recovery can lead to increased costs 
for arsenic removal. Since the ability to blend with an MCL of 5 
g/L would be limited, the entire stream may have to be 
treated. Therefore, most of the alkalinity and hardness would also be 
removed. In that case, to avoid corrosion problems and to restore 
minerals to the water, post-treatment corrosion control may be 
necessary. Discharge of reject water or brine may also be a concern.
    Electrodialysis Reversal (EDR) can produce effluent water quality 
comparable to reverse osmosis. EDR systems are fully automated, require 
little operator attention, and do not require chemical addition. EDR 
systems, however, are typically more expensive than nanofiltration and 
reverse osmosis systems. These systems are often used in treating 
brackish water to make it suitable for drinking. This technology has 
also been applied in the industry for wastewater recovery. The 
technology typically operates at a recovery of 70 to 80 percent. Few 
studies have been conducted to exclusively evaluate this process for 
the removal of arsenic, but a removal of approximately 85% can be 
expected (US EPA, 1999i).

Other Technologies

    Coagulation Assisted Microfiltration. The coagulation process 
described previously can be linked with microfiltration to remove 
arsenic. The microfiltration step essentially takes the place of a 
conventional gravity filter. The University of Houston recently 
completed pilot studies at Albuquerque, New Mexico on iron coagulation 
followed by a direct microfiltration system. The results of this study 
indicated that iron coagulation followed by microfiltration is capable 
of removing arsenic (V) from water to yield concentrations which are 
consistently below 2 g/L. Critical operating parameters are 
iron dose, mixing energy, detention time, and pH (Clifford, 1997). 
However, since a full-scale operation history is one of the 
requirements to list a technology as a BAT, it is not presently being 
listed as one. It could be designated as such in the future if the 
technology meets that requirement.
    Oxidation/Filtration (including greensand filtration) has an 
advantage in that there is not as much competition with other ions. 
However, the process has not been used very much for arsenic removal. 
In addition, similar to activated alumina, greensand filtration may 
require pH adjustment to optimize removal, which may be difficult for 
small systems. This technology is not recommended for high removals. 
The maximum removal percentage was assumed to be 50% when estimating 
national costs. The presence of iron in the source water is critical 
for arsenic removal. If the source water does not contain iron, 
oxidizing and filtering the water will not remove arsenic. In 
developing national cost estimates, it was assumed that systems would 
opt for this type of technology only if more than 300 g/L of 
iron was present. Oxidation/Filtration is not being listed as a BAT 
because it does not meet the requirement of a high removal efficiency. 
However, since it is a relatively inexpensive technology, it may be 
appropriate for those systems that do not require much arsenic removal 
and have high iron in their source water.

Emerging Technologies

    There are several emerging technologies for arsenic removal; 
however, these require more testing before they can be designated as a 
BAT. Iron-based media products include the following. Iron oxide coated 
sand removes arsenic using adsorption; the sand also doubles as a 
filtration media. The technology has only been tested at the bench-
scale level and may have a high cost associated with it. Granular 
ferric hydroxide also employs an adsorption process and is being used 
in a number of full scale plants in Germany. Costs may be an issue with 
this technology as well. Iron filings are essentially a filter 
technology, initially developed for arsenic remediation. Though quite 
effective at remediation, this technology may have limited use as a 
drinking water treatment technology; the technology performs well when 
treating high influent arsenic levels typical of remediation, but needs 
to be proven in treating lower influent levels expected in raw drinking 
water to a finished level at the proposed MCL.

[[Page 38924]]

Sulfur-modified iron appears to remove total organic carbon (TOC) and 
disinfection byproducts (DBPs) as well as arsenic. However, it has only 
been tested at the bench scale. ADI Group, Inc.''s proprietary process 
also has an iron-based media that has been installed in a number of 
locations.
    Nanofiltration is of interest because it can be operated at lower 
pressures than reverse osmosis, which translate into lower operation 
and maintenance costs. However, when nanofiltration is operated at 
realistic recoveries, the removal efficiency appears to be low.
    Electrodialysis Reversal (EDR), although easier to operate than 
reverse osmosis and nanofiltration, does not appear to be competitive 
with respect to costs and process efficiency.

Waste Disposal

    Waste disposal will be an important issue for both large and small 
plants. Costs for waste disposal have been added to the costs of the 
treatment technologies (in addition to any pre-oxidation and corrosion 
control costs), and form part of the treatment trains that are listed 
in Section VIII.B. A sufficient volume of receiving water would be 
needed in order to directly discharge the contaminated brine stream 
from membrane technologies. Otherwise, operators may have to pre-treat 
to meet Clean Water Act permit requirements prior to discharge. If the 
plant is discharging to a sanitary sewer because of the membranes, 
there may be a very high salinity in the discharge as well as high 
levels of arsenic that might, without pretreatment, exceed local sewer 
use regulations. Ion exchange and activated alumina treatment brines 
will be even more concentrated (on the order of 30,000 TDS), and more 
than likely will require pre-treatment prior to discharge to either a 
receiving body of water or the sanitary sewer.
    Disposal of solid treatment residuals would be problematic if they 
fail the toxicity characteristic (TC) of the Resource Conservation and 
Recovery Act (RCRA). If they fail the TC, the residuals are regulated 
as hazardous waste because of the concentration of arsenic. For the 
purposes of the national cost estimate, it was assumed that solid 
residuals would be disposed of at nonhazardous landfills.

B. What Are the Likely Treatment Trains? How Much Will They Cost?

    Likely treatment trains are shown in Table VIII-2. These trains 
represent a wide variety of solutions a facility may consider when 
complying with the proposed arsenic MCL. Not all solutions may be 
viable for a given system. For example, only those systems with 
coagulation/filtration in-place will be able to modify their existing 
treatment system. The treatment trains include BATs, waste disposal, 
and when necessary, pre-oxidation and corrosion control.
    Table VIII-2 also contains two ``non-treatment'' options which may 
be appropriate if the source water is of very poor quality. 
``Regionalization'' refers to connecting with another system and 
purchasing water, and ``alternate source'' refers to finding a new 
source of water (e.g. drilling a new well). However, since arsenic is a 
naturally occurring contaminant, it may be ubiquitous at a particular 
site, so drilling another well may not improve the situation.

               Table VIII-2.--Treatment Technology Trains
------------------------------------------------------------------------
          Train  No.                  Treatment technology trains
------------------------------------------------------------------------
1............................  Regionalization.
2............................  Alternate Source.
3............................  Add pre-oxidation [if not in-place] and
                                modify in-place Lime Softening.
4............................  Add pre-oxidation [if not in-place] and
                                modify in-place Coagulation/Filtration.
5............................  Add pre-oxidation [if not in-pace] and
                                add Anion Exchange and add POTW waste
                                disposal and add corrosion control [if
                                >90% removal required]. Sulfate level at
                                25 mg/l.
6............................  Add pre-oxidation [if not in-place] and
                                add Anion Exchange and add POTW waste
                                disposal and add corrosion control [if
                                >90% removal required]. Sulfate level at
                                150 mg/l.
7............................  Add pre-oxidation [if not in-place] and
                                add Anion Exchange and add evaporation
                                pond/non-hazardous landfill waste
                                disposal and add corrosion control [if
                                >90% removal required]. Sulfate level at
                                25 mg/l.
8............................  Add pre-oxidation [if not in-place] and
                                add Anion Exchange and evaporation pond/
                                non-hazardous landfill waste disposal
                                and add corrosion control [if >90%
                                removal required]. Sulfate level at 150
                                mg/l.
9............................  Add pre-oxidation [if not in-place] and
                                add Activated Alumina and add non-
                                hazardous landfill (for spent media)
                                waste disposal. pH at 7.
10...........................  Add pre-oxidation [if not in-pace] and
                                add Reverse Osmosis and add direct
                                discharge waste disposal and add
                                corrosion control [if >90% removal
                                required].
11...........................  Add pre-oxidation [if not in-place] and
                                add Reverse Osmosis and add POTW waste
                                disposal and add corrosion control [if
                                >90% removal required].
12...........................  Add pre-oxidation [if not in-place] and
                                add Reverse Osmosis and add chemical
                                precipitation/non-hazardous landfill and
                                add corrosion control [if >90% removal
                                required].
13...........................  Add pre-oxidation [if not in-place] and
                                add Coagulation Assisted Microfiltration
                                and add mechanical dewatering/non-
                                hazardous landfill waste disposal.
14...........................  Add pre-oxidation [if not in-place] and
                                add Coagulation Assisted Microfiltration
                                and add non-mechanical dewatering/non-
                                hazardous landfill waste disposal.
15...........................  Add pre-oxidation [if not in-place] and
                                add Oxidation/Filtration (Greensand) and
                                add POTW for backwash stream.
16...........................  Add pre-oxidation [if not in-place] and
                                add Anion Exchange and add chemical
                                precipitation/non-hazardous landfill
                                waste disposal and add corrosion control
                                [if >90% removal required]. Sulfate
                                level at 25 mg/l.
17...........................  Add pre-oxidation [if not in-place] and
                                add Anion Exchange and add chemical
                                precipitation/non-hazardous landfill
                                waste disposal and add corrosion control
                                [if >90% removal required]. Sulfate
                                level at 150 mg/l.
18...........................  Add pre-oxidation [if not in-place] and
                                add Activated Alumina and add POTW/non-
                                hazardous landfill waste disposal. pH at
                                7.
19...........................  Add pre-oxidation [if not in-place] and
                                add POE Activated Alumina.
20...........................  Add pre-oxidation [if not in-place] and
                                add POU Reverse Osmosis.
21...........................  Add pre-oxidation [if not in-place] and
                                add POU Activated Alumina.
------------------------------------------------------------------------


[[Page 38925]]

    Costs for each of these treatment trains are given in Table VIII-3. 
These costs are a function of system size. Some individual systems may 
experience household costs higher than those estimated in this table. 
The pre-oxidation costs and corrosion control costs are given 
separately for each system size category because they will only be 
incurred by some of the systems. In estimating national costs, it was 
assumed that only systems without pre-oxidation in-place would add the 
necessary equipment. It is expected that no surface water systems will 
need to install pre-oxidation for arsenic removal. Based on Table IX-4, 
it is expected that fewer than 50% of the ground water systems may need 
to install pre-oxidation for arsenic removal. Ground water systems 
without pre-oxidation should determine if pre-oxidation is necessary by 
determining if the arsenic is present as As (III) or As (V). 
Groundwater systems with predominantly As (V) will probably not need 
pre-oxidation to meet the MCL. Similarly, costs for corrosion control 
were only added to systems that used ion exchange or reverse osmosis to 
remove more than 90% of the arsenic in the raw water. It is expected 
that fewer than 1% of the affected systems will need to install 
corrosion control due to installation of arsenic treatment. For ion 
exchange, different treatment trains were used for two levels of 
sulfate. As sulfate affects regeneration frequency, the high sulfate 
treatment train is more expensive than the low sulfate treatment train.

                                             Table VIII-3.--Annual Costs of Treatment Trains (Per Household)*
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                           Size
                                                                 ---------------------------------------------------------------------------------------
                         Treatment train                                                           1001-3300
                                                                    25-100    101-500    501-1000              3301-10K   10K-50K    50K-100K   100K-1M
                                                                  (dollars)  (dollars)  (dollars)  (dollars)  (dollars)  (dollars)  (dollars)  (dollars)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1...............................................................     $ 1347      $ 202       $ 77       $ 25        $ 8        $ 2        $ 1        $ 0
2...............................................................         96         14          5          2          1          0          0          0
3...............................................................        750        138         70         40         30         26         22         18
4...............................................................        462         82         40         22         49         60         38         18
5...............................................................        519        146         90        106         73         55         44         39
6...............................................................        883        248        160        160         78         60         49         44
7...............................................................        629        226        153        154        108         84         71         58
8...............................................................       1227        469        333        290        197        165        135         88
9...............................................................        384        227        201        182        168        152        144        143
10..............................................................       2136        800        555        429        300        256        225        206
11..............................................................       2136        800        555        429        300        256        225        206
12..............................................................       2819        892        572        409        293        237        204        186
13..............................................................       1282        293        195        125         72         50         32         18
14..............................................................       1218        281        187        117         80         54         35         21
15..............................................................        558        156        102         72         55         42         37         31
16..............................................................       1008        222        121        128         86         58         46         40
17..............................................................       1050        246        115        114         96         66         52         45
18..............................................................        427        243        212        192        177        161        153        152
19..............................................................        467        427        408        388        367        342        327        298
20..............................................................        325        289        272        254        236        214        202        178
21..............................................................        377        334        314        292        271        245        230        202
pre-ox**........................................................        416         66         26          9          4          2          1          1
corros**........................................................         63         17         11          6          5          3          3         3
--------------------------------------------------------------------------------------------------------------------------------------------------------
 *These costs are based on a discount rate of 7%.
**The costs for treatment trains 1-21 do not include pre-oxidation or corrosion control costs. For systems that need to add pre-oxidation or corrosion
  control, the costs for these additional treatments should be added to those of the trains shown in the table.

C. How Are Variance and Compliance Technologies Identified for Small 
Systems?

    Section 1415(e)(1) of SDWA allows States to grant variances to 
small water systems (i.e., systems having fewer than 10,000 customers) 
in lieu of complying with an MCL if EPA determines that there are no 
nationally affordable compliance technologies for that system size/
water quality combination. The system must then install an EPA-listed 
variance treatment technology (section 1412(b)(15)) that makes progress 
toward the MCL, if not necessarily reaching it. To list variance 
technologies, three showings must be made:
    (1) EPA must determine, on a national level, that there are no 
compliance technologies that are affordable for the given small system 
size category/source water quality combination.
    (2) If there is no nationally affordable compliance technology, 
then EPA must identify a variance technology that may not reach the MCL 
but that will allow small systems to make progress toward the MCL (it 
must achieve the maximum reduction affordable). This technology must be 
listed as a small systems variance technology by EPA in order for small 
systems to be able to rely on it for regulatory purposes.
    (3) EPA must make a finding on a national level, that use of the 
variance technology would be protective of public health and establish.
    Primacy States must then make a site-specific determination for 
each system as to whether or not the system can afford to meet the MCL 
based on State-developed affordability criteria. If the State 
determines that compliance is not affordable for the system, it may 
grant a variance, but it must establish terms and conditions, as 
necessary, to ensure that the variance is adequately protective of 
human health.
    In the Agency's draft national-level affordability criteria 
published in the August 6, 1998 Federal Register (US EPA, 1998h), EPA 
discussed the affordable treatment technology determinations for the 
contaminants regulated before 1996. The national-level affordability 
criteria were derived as follows. First an ``affordability threshold'' 
(i.e., the total annual household water bill that would be considered 
affordable) was calculated. In developing this threshold value, EPA 
considered the percentage of median

[[Page 38926]]

household income spent by an average household on comparable goods and 
services such items as housing (28%), transportation (16%), food (12%), 
energy and fuels (3.3%), telephone (1.9%), water and other public 
services (0.7%), entertainment (4.4%) and alcohol and tobacco (1.5%).
    Another of the key factors that EPA used to select an affordability 
threshold was cost comparisons with other risk reduction activities for 
drinking water. Section 1412(b)(4)(E)(ii) of the SDWA identifies both 
Point-of-Entry and Point-of-Use devices as options for compliance 
technologies. EPA examined the projected costs of these options. EPA 
also investigated the costs associated with supplying bottled water for 
drinking and cooking purposes. The median income percentages that were 
associated with these risk reduction activities were: Point-of-Entry 
(>2.5%), Point-of-Use (2%) and bottled water (>2.5%). The complete 
rationale for EPA's selection of 2.5% as the affordability threshold is 
described in Variance Technology Findings for Contaminants Regulated 
Before 1996 (US EPA, 1998f).
    Based on the foregoing analysis, EPA developed an affordability 
criteria of 2.5% of median household income, or about $750, for the 
affordability threshold (US EPA 1998f). The median water bill for 
households in each small system category was then subtracted from this 
threshold to determine the affordable level of household expenditures 
for new treatment. This difference is referred to as the ``available 
expenditure margin.'' Based on EPA's 1995 Community Water System 
Survey, median water bills were about $250 per year for small system 
customers. Thus, an average available expenditure margin of up to $500 
per year was considered affordable for the contaminants regulated 
before 1996. However, EPA expects the available expenditure margin may 
be lower than $500 per household per year for the arsenic rule because 
EPA believes that water rates are currently increasing faster than 
median household income. Thus, the ``baseline'' for annual water bills 
will rise as treatment is installed for compliance with regulations 
promulgated after 1996, but before the arsenic rule is promulgated.
    To account for this, EPA intends to adjust its calculation of the 
baseline for the affordability criteria as follows. The national median 
annual household water bills for each size category will be adjusted by 
averaging the total national costs for the size category over all of 
the systems within the size category. In other words, the costs 
incurred by these rules at the affected water systems will be averaged 
over all of the systems in that size category. A revised available 
expenditure margin will be calculated by subtracting the new baseline 
from the affordability threshold. The affordable technology 
determinations will be made by comparing the projected costs of 
treatment against the lower available expenditure margin. If the 
projected costs of all treatment technologies for a given system size/
source water quality exceed the revised available expenditure margin, 
then variance technologies could be considered for those systems. EPA 
requests comment on this method of accounting for new regulations in 
its affordability criteria.
    Applying the affordability criterion to the case of arsenic in 
drinking water, EPA has determined that affordable technologies exist 
for all system size categories and has therefore not identified a 
variance technology for any system size or source water combination at 
the proposed MCL. (See Table IX-12, Total Annual Costs per Household.) 
In other words, annual household costs are projected to be below the 
available affordability threshold for all system size categories for 
the proposed MCL. EPA solicits comment on its determination in this 
case as well as its affordability criteria more generally.
    EPA recognizes that individual water systems may have higher than 
average treatment costs, fewer than average households to absorb these 
costs, or lower than average incomes, but believes that the 
affordability criteria should be based on characteristics of typical 
systems and should not address situations where costs might be 
extremely high or low or excessively burdensome. EPA believes that 
there are other mechanisms that may address these situations to a 
certain extent, such as rates for disadvantaged communities and grants. 
For instance, many utilities extend special ``lifeline'' rates to 
disadvantaged communities.
    EPA also notes that high water costs are often associated with 
systems that have already installed treatment to comply with a NPDWR. 
Such treatment facilities may also facilitate compliance with future 
standards. EPA's approach to establishing the national-level 
affordability criteria did not incorporate a baseline for in-place 
treatment technology. Assuming that systems with high baseline water 
costs would need to install a new treatment technology to comply with a 
NPDWR may thus overestimate the actual costs for some systems.
    To investigate this issue, EPA examined a group of five small 
surface water systems with annual water bills above $500 per household 
per year during the derivation of the national-level affordability 
criteria. All of these systems had installed disinfection and 
filtration technologies to comply with the surface water treatment 
rule. If these systems exceeded the revised arsenic standard, 
modification of the existing processes would be much more cost-
effective than adding a new technology to comply with the arsenic rule. 
These systems have already made the investment in treatment technology 
and that is reflected in the current annual household water bills.
    In addition, systems that meet criteria established by the State 
could be classified as disadvantaged communities under section 1452(d) 
of the SDWA. They can receive additional subsidization under the 
Drinking Water State Revolving Fund (DWSRF) program, including 
forgiveness of principal. Under DWSRF, States must provide a minimum of 
15% of the available funds for loans to small communities and have the 
option of providing up to 30% of the grant to provide additional loan 
subsidies to the disadvantaged systems, as defined by the State.
    As previously noted in today's proposal, some technologies can 
interfere with treatment in-place or require additional treatment to 
address side effects which will increase costs over the arsenic 
treatment technology base costs. (An example is corrosion control for 
lead and copper, which may need to be adjusted to accommodate other 
treatment). While EPA tries to account for such interferences in its 
cost estimates for each new compliance technology, it is not possible 
to anticipate all the site specific issues which may arise. However, 
EPA has included a discussion of the co-occurrence of radon, sulfate, 
and iron in this proposal. EPA will also provide guidance identifying 
cost-effective treatment trains for ground water systems that need to 
treat for both arsenic and radon after the arsenic rule is finalized.
    EPA encourages small systems to discuss their infrastructure needs 
for complying with the arsenic rule with their primacy agency to 
determine their eligibility for DWSRF loans, and if eligible, to ask 
for assistance in applying for the loans.

D. When Are Exemptions Available?

    Under section 1416(a), the State may exempt a public water system 
from any MCL and/or treatment technique requirement if it finds that 
(1) due to compelling factors (which may include economic factors), the 
system is unable

[[Page 38927]]

to comply or develop an alternative supply, (2) the system was in 
operation on the effective date of the MCL or treatment technique 
requirement, or, for a newer system, that no reasonable alternative 
source of drinking water is available to that system, (3) the exemption 
will not result in an unreasonable risk to health, and (4) management 
or restructuring changes cannot be made that would result in compliance 
with this rule. Under section 1416(b), at the same time it grants an 
exemption the State is to prescribe a compliance schedule and a 
schedule for implementation of any required control measures. The final 
date for compliance may not exceed three years after the NPDWR 
effective date except that the exemption can be renewed for small 
systems for limited time periods.

E. What Are the Small Systems Compliance Technologies?

    Section 1412(b)(4)(E)(ii) of SDWA, as amended in 1996, requires EPA 
to issue a list of technologies that achieve compliance with MCLs 
established under the Act that are affordable and applicable to typical 
small drinking water systems. These small public water systems 
categories are: (1) Population of more than 25 but less than 500; (2) 
Population of more than 500, but less than 3,300; and (3) Population of 
more than 3,300, but less than 10,000. Owners and operators may choose 
any technology or technique that best suits their conditions, as long 
as the MCL is met.
    Of the treatment trains identified in section VIII.B., the ones 
identified in Table VIII-4 are deemed to be affordable for systems 
serving 25-500 people and the ones identified in Table VIII-5 are 
deemed to be affordable for systems serving 501-3,300 and 3,301-10,000 
people, as their annual costs are below the affordability threshold (US 
EPA, 1999g). Because affordable compliance technologies are available, 
the Agency does not propose to identify any variance technologies. EPA 
requests comments on the affordable compliance technology 
determinations for the three size categories and the determination that 
there will be no variance technologies. Centralized compliance 
treatment technologies include ion exchange, activated alumina, 
modified coagulation/filtration, modified lime softening, and 
oxidation/filtration (e.g. greensand filtration) for source waters high 
in iron. In addition, point-of-use (POU) and point-of-entry (POE) 
devices are also compliance technology options for the smaller systems. 
EPA is aware that very few water systems have had experience with 
centrally managed POU or POE options in the past. EPA requests comments 
on implementation issues associated with a centrally managed POU or POE 
option for arsenic. The non-treatment alternatives are especially 
relevant for small systems. EPA is proposing to add the abbreviations 
``POU'' and ``POE'' to the definitions in Sec. 141.2 and asks for 
comment on the utility of adding them.

Table VIII-4.--Affordable Compliance Technology Trains for Small Systems
                         With population 25-500
------------------------------------------------------------------------
             Train No.                   Treatment technology trains
------------------------------------------------------------------------
3.................................  Add pre-oxidation [if not in-place]
                                     and modify in-place Lime Softening
4.................................  Add pre-oxidation [if not in-place]
                                     and modify in-place Coagulation/
                                     Filtration
5.................................  Add pre-oxidation [if not in-place]
                                     and add Anion Exchange and add POTW
                                     waste disposal and add corrosion
                                     control [if >90% removal required].
                                     Sulfate level at 25 mg/l.
6.................................  Add pre-oxidation [if not in-place]
                                     and add Anion Exchange and add POTW
                                     waste disposal and add corrosion
                                     control [if >90% removal required].
                                     Sulfate level at 150 mg/l.
7.................................  Add pre-oxidation [if not in-place]
                                     and add Anion Exchange and add
                                     evaporation pond/non-hazardous
                                     landfill waste disposal and add
                                     corrosion control [if >90% removal
                                     required]. Sulfate level at 25 mg/
                                     l.
8.................................  Add pre-oxidation [if not in-place]
                                     and add Anion Exchange and
                                     evaporation pond/non-hazardous
                                     landfill waste disposal and add
                                     corrosion control [if >90% removal
                                     required]. Sulfate level at 150 mg/
                                     l.
9.................................  Add pre-oxidation [if not in-place]
                                     and add Activated Alumina and add
                                     non-hazardous landfill (for spent
                                     media) waste disposal. pH at 7.
15................................  Add pre-oxidation [if not in-place]
                                     and add Oxidation/Filtration
                                     (Greensand) and add POTW for
                                     backwash stream.
16................................  Add pre-oxidation [if not in-place]
                                     and add Anion Exchange and add
                                     chemical precipitation/non-
                                     hazardous landfill waste disposal
                                     and add corrosion control [if >90%
                                     removal required]. Sulfate level at
                                     25 mg/l.
17................................  Add pre-oxidation [if not in-place]
                                     and add Anion Exchange and add
                                     chemical precipitation/non-
                                     hazardous landfill waste disposal
                                     and add corrosion control [if >90%
                                     removal required]. Sulfate level at
                                     150 mg/l.
18................................  Add pre-oxidation [if not in-place]
                                     and add Activated Alumina and add
                                     POTW/non-hazardous landfill waste
                                     disposal. pH at 7.
19................................  Add pre-oxidation [if not in-place]
                                     and add POE Activated Alumina.
20................................  Add pre-oxidation [if not in-place]
                                     and add POU Reverse Osmosis.
21................................  Add pre-oxidation [if not in-place]
                                     and add POU Activated Alumina.
------------------------------------------------------------------------


Table VIII-5.--Affordable Compliance Technology Trains for Small Systems
             With populations 501-3,300 and 3,301 to 10,000
------------------------------------------------------------------------
             Train No.                   Treatment technology trains
------------------------------------------------------------------------
3.................................  Add pre-oxidation [if not in-place]
                                     and modify in-place Lime Softening
4.................................  Add pre-oxidation [if not in-place]
                                     and modify in-place Coagulation/
                                     Filtration
5.................................  Add pre-oxidation [if not in-place]
                                     and add Anion Exchange and add POTW
                                     waste disposal and add corrosion
                                     control [if >90% removal required].
                                     Sulfate level at 25 mg/l.
6.................................  Add pre-oxidation [if not in-place]
                                     and add Anion Exchange and add POTW
                                     waste disposal and add corrosion
                                     control [if >90% removal required].
                                     Sulfate level at 150 mg/l.
7.................................  Add pre-oxidation [if not in-place]
                                     and add Anion Exchange and add
                                     evaporation pond/non-hazardous
                                     landfill waste disposal and add
                                     corrosion control [if >90% removal
                                     required]. Sulfate level at 25 mg/
                                     l.
8.................................  Add pre-oxidation [if not in-place]
                                     and add Anion Exchange and
                                     evaporation pond/non-hazardous
                                     landfill waste disposal and add
                                     corrosion control [if >90% removal
                                     required]. Sulfate level at 150 mg/
                                     l.

[[Page 38928]]

 
9.................................  Add pre-oxidation [if not in-place]
                                     and add Activated Alumina and add
                                     non-hazardous landfill (for spent
                                     media) waste disposal. pH at 7.
10................................  Add pre-oxidation [if not in-place]
                                     and add Reverse Osmosis and add
                                     direct discharge waste disposal and
                                     add corrosion control [if >90%
                                     removal required].
11................................  Add pre-oxidation [if not in-place]
                                     and add Reverse Osmosis and add
                                     POTW waste disposal and add
                                     corrosion control [if >90% removal
                                     required].
12................................  Add pre-oxidation [if not in-place]
                                     and add Reverse Osmosis and add
                                     chemical precipitation/non-
                                     hazardous landfill and add
                                     corrosion control [if >90% removal
                                     required].
13................................  Add pre-oxidation [if not in-place]
                                     and add Coagulation Assisted
                                     Microfiltration and add mechanical
                                     dewatering/non-hazardous landfill
                                     waste disposal.
14................................  Add pre-oxidation [if not in-place]
                                     and add Coagulation Assisted
                                     Microfiltration and add non-
                                     mechanical dewatering/non-hazardous
                                     landfill waste disposal.
15................................  Add pre-oxidation [if not in-place]
                                     and add Oxidation/Filtration
                                     (Greensand) and add POTW for
                                     backwash stream.
16................................  Add pre-oxidation [if not in-place]
                                     and add Anion Exchange and add
                                     chemical precipitation/non-
                                     hazardous landfill waste disposal
                                     and add corrosion control [if >90%
                                     removal required]. Sulfate level at
                                     25 mg/l.
17................................  Add pre-oxidation [if not in-place]
                                     and add Anion Exchange and add
                                     chemical precipitation/non-
                                     hazardous landfill waste disposal
                                     and add corrosion control [if >90%
                                     removal required]. Sulfate level at
                                     150 mg/l.
18................................  Add pre-oxidation [if not in-place]
                                     and add Activated Alumina and add
                                     POTW/non-hazardous landfill waste
                                     disposal. pH at 7.
19................................  Add pre-oxidation [if not in-place]
                                     and add POE Activated Alumina.
20................................  Add pre-oxidation [if not in-place]
                                     and add POU Reverse Osmosis.
21................................  Add pre-oxidation [if not in-place]
                                     and add POU Activated Alumina.
------------------------------------------------------------------------

    Centralized treatment is not always a feasible option. When this is 
the situation, home water treatment devices can be effective and 
affordable compliance options for small systems in meeting the proposed 
arsenic MCL. Home water treatment can consist of either whole-house 
(point-of-entry) or single faucet (point-of-use) treatment.
    Whole-house, or POE treatment, is necessary when exposure to the 
contaminant by modes other than consumption is a concern; this is not 
the case with arsenic. Single faucet, or POU treatment, is preferred 
when treated water is needed only for drinking and cooking purposes. 
POU devices are especially applicable for systems that have a large 
flow and only a minor part of that flow directed for potable use. POE/
POU options include reverse osmosis, activated alumina, and ion 
exchange processes. POU systems are easily installed and can be easily 
operated and maintained. In addition, these systems generally offer 
lower capital costs and may reduce engineering, legal, and other fees 
associated with centralized treatment options.
    Allowing the usage of POU devices is one of the new elements of the 
Safe Drinking Water Act; on June 11, 1998, EPA issued a Federal 
Register notice (US EPA, 1998i) to withdraw the prohibition on the use 
of POU devices as compliance technologies. The SDWA stipulates that 
POU/POE treatment systems ``shall be owned, controlled and maintained 
by the public water system, or by a person under contract with the 
public water system to ensure proper operation and compliance with the 
MCL or treatment technique and equipped with mechanical warnings to 
ensure that customers are automatically notified of operational 
problems.''
    Using POU/POE devices introduces some new issues. Adopting a POU/
POE treatment system in a small community requires more record-keeping 
to monitor individual devices than does central treatment. POU/POE 
systems require special regulations regarding customer responsibilities 
and water utility responsibilities. Use of POU/POE systems does not 
reduce the need for a well-maintained water distribution system. On the 
contrary, increased monitoring may be necessary to ensure that the 
treatment units are operating properly.
    Water systems with high influent arsenic concentrations (i.e., 
greater than 1 mg/L) may have difficulty meeting the proposed MCL when 
POU/POE devices are used. As a result, influent arsenic concentration 
and other source water characteristics must be considered when 
evaluating POU/POE devices for arsenic removal.
    EPA assumed that systems would more likely opt to use POU AA or RO 
(and not IX), and POE AA (and not IX nor RO), when developing national 
cost estimates (refer to Table VIII-4). Activated alumina and ion 
exchange units face a breakthrough issue. If the media or resin is not 
replaced and/or regenerated on time, there is a potential for 
significantly reduced arsenic removal. Activated alumina units have the 
advantage of longer run lengths and the option to use the media once 
and throw it away. However, if POE ion exchange units are regenerated 
on time, they would also be an effective treatment technology. Units 
with automatic regeneration are thus viable options. POE IX and RO 
units also have a potential for creating corrosion control problems. 
With ion exchange POE units, a reduction in pH can be expected 
initially with new resin, but the pH reduction should subside over 
time.

F. How Does the Arsenic Regulation Overlap With Other Regulations?

    Several Federal rules are under development regarding treatment 
requirements that may relate to the treatment of arsenic for this 
drinking water rule. The following briefly describes each rule, the 
impact the Arsenic Rule may have on that rule, and/or how each rule may 
impact the arsenic standard. The Arsenic Rule is expected to be 
promulgated in a similar time frame as the Ground Water Rule, the Radon 
Rule, and the Microbial and Disinfection By-Product Rule (Final 
December, 1998). In addition, the disposal of residuals may be affected 
by the hazardous waste regulations of the Resource Conservation and 
Recovery Act (RCRA).
    Ground Water Rule (GWR). The goals of the GWR are to: (1) Provide a 
consistent level of public health protection; (2) prevent waterborne

[[Page 38929]]

microbial disease outbreaks; (3) reduce endemic waterborne disease; and 
(4) prevent fecal contamination from reaching consumers. EPA has the 
responsibility to develop a ground water rule which not only specifies 
the appropriate use of disinfection, but also addresses other 
components of ground water systems to assure public health protection. 
This general provision is supplemented with an additional requirement 
that EPA develop regulations specifying the use of disinfectants for 
ground water systems as necessary. To meet these requirements, EPA 
worked with stakeholders to develop a Ground Water Rule proposal (US 
EPA, 2000d) and plans to issue a final rule by late Fall 2000.
    The GWR will result in more systems using disinfection. Under the 
GWR, a system has options other than disinfection (e.g., protecting 
source water). However, if a system does add a disinfection technology, 
it may contribute to arsenic pre-oxidation. This largely depends on the 
type of disinfection technology employed. If a system chooses a 
technology such as ultraviolet radiation, it may not affect arsenic 
pre-oxidation. However, if it chooses chlorination, it will contribute 
to arsenic pre-oxidation. As discussed previously, arsenic pre-
oxidation from As (III) to As (V) will enhance the removal efficiencies 
of the technologies. In addition, systems may use membrane filtration 
for the GWR. In that case, depending on the size of the membrane, some 
arsenic removal can be achieved. Thus, the GWR is expected to alleviate 
some of the burden of the Arsenic Rule.
    Radon. In the 1996 Amendments to the SDWA, Congress (section 
1412(b)(13)) directed EPA to propose an MCLG and NPDWR for radon by 
August, 1999 (proposed on December 21, 1999, US EPA 1999n) and finalize 
the regulation by August, 2000 (section 1412(b)(13)). Like the Ground 
Water Rule, the Radon Rule will also be finalized before the Arsenic 
Rule. Systems may employ aeration to comply with the radon rule. 
Aeration alone, however, will not likely be sufficient to oxidize 
arsenic (III) to arsenic (V). However, if systems do aerate, they may 
be required by State regulations to also disinfect. The disinfection 
process may oxidize the arsenic, depending on the type of disinfection 
employed. Ultraviolet disinfection may not assist in arsenic oxidation 
(still under investigation by US EPA), whereas chemical disinfection or 
oxidation is likely to. Thus, the Radon Rule is expected to alleviate 
some of the burden of the Arsenic Rule.
    Microbial and Disinfection By-product Regulations. To control 
disinfection and disinfection byproducts and to strengthen control of 
microbial pathogens in drinking water, EPA is developing a group of 
interrelated regulations, as required by the SDWA. These regulations, 
referred to collectively as the Microbial Disinfection By-product (M/
DBP) Rules, are intended to address risk trade-offs between the two 
different types of contaminants.
    EPA proposed a Stage 1 Disinfectants/Disinfection By-products Rule 
(DBPR) and Interim Enhanced Surface Water Treatment Rule (IESWTR) in 
July 1994. EPA issued the final Stage 1 DBPR and IESWTR in November, 
1998.
    The Agency has finalized and is currently implementing a third 
rule, the Information Collection Rule, that will provide data to 
support development of subsequent M/DBP regulations. These subsequent 
rules include a Stage 2 DBPR and a companion Long-Term 2 Enhanced 
Surface Water Treatment Rule (LT2ESWTR).
    The IESWTR will primarily affect large surface water systems, so 
EPA does not expect much overlap with small systems treating for 
arsenic. However, the Stage 1 DBPR will affect both large and small 
sized systems and may overlap with small systems treating for arsenic. 
In addition, the Stage 2 DBPR and possibly the LT2ESWTR would have 
significance as far as arsenic removal is concerned. For systems 
removing DBP precursors, systems may use nanofiltration. The use of 
nanofiltration would also be relevant for removing arsenic, and as a 
result, would ease some burden when systems implement these later 
rules.
    Hazardous Waste. The current toxicity characteristic (TC) 
regulatory level for designating arsenic as a hazardous waste under the 
Resource Conservation and Recovery Act (RCRA) is 5 mg/L and is listed 
in 40 CFR 261.24(a). It is important to differentiate between the 
toxicity characteristic and the toxicity characteristic leaching 
procedure (TCLP). The TCLP is the method by which a waste is evaluated 
to determine if it exceeds the toxicity characteristic. It is also 
important to note that while the toxicity characteristic was based on 
multiplying the current drinking water MCL by a factor of 100, the TC 
is not directly linked to the drinking water MCL. Thus, lowering the 
drinking water MCL does not mean that the toxicity characteristic would 
be lowered. A separate RCRA rulemaking would be required to lower the 
toxicity characteristic regulatory level. The drinking water standards 
for several inorganic contaminants have been lowered without any 
lowering of the toxicity characteristic. For example, the cadmium MCL 
was lowered from 10 g/L to 5 g/L in 1991, but the TC 
for cadmium still remains at 1.0 mg/L. The drinking water standard for 
lead was revised from an MCL of 50 g/L to an action level of 
15 g/L. Both drinking water standards were lowered in 1991. 
The TC for lead remains at 5 mg/L. The studies summarized below show 
that arsenic residuals should be below the current TC of 5 mg/L and 
could be disposed in a non-hazardous landfill.
    In one study, sludges from four different water treatment plants 
were evaluated. (Bartley et al. 1992). There are data from two lime 
softening plants, one plant with both lime softening and coagulation/
filtration processes, and one arsenic removal plant utilizing 
coagulation/filtration. The raw water arsenic in the tow lime softening 
plants and the one plant using both lime softening and coagulation/
filtration were below 0.001 mg/L. The arsenic removal plant was 
removing arsenic from 1.1 mg/L to 0.42 mg/L using ferric sulfate 
coagulation. The product water was blended with water from another 
source to comply with the MCL. The TCLP extracts ranged from 0.007 to 
0.039 mg/L, which is considerably below the current criterion for being 
designated a hazardous waste under RCRA.
    In another study, TCLP tests were performed using the activated 
alumina from two activated alumina plants (Wang et al., 2000). Both 
plants had similar setups (one is referred to as CS, the other is 
referred to as BES). Both systems consist of four tanks of activated 
alumina with two parallel sets of two tanks in series. The first set of 
tanks are used as roughing filters and the second set of tanks are used 
as polishing filters. The units were not regenerated, but replaced. For 
the CS system, the influent arsenic concentration ranged from 0.053 to 
0.087 mg/L with an average of 0.062 mg/L. The effluent arsenic 
concentration was consistently below 0.005 mg/L. When the activated 
alumina media was removed from the roughing filters, three samples were 
taken. All three samples had arsenic TCLP test results of less than 
0.05 mg/L. Again, these results were well below the regulatory limit.
    The influent arsenic concentration of the activated alumina plant 
referred to as BES ranged from 0.021 to 0.076 mg/L, with an average of 
0.049 mg/L. Effluent levels were also less than 0.005 mg/L. When the 
media was removed from the two roughing filters, TCLP tests were taken. 
The results were 0.05 mg/

[[Page 38930]]

L and 0.066 mg/L. Again, the results were below the regulatory limit.
    Another study examined residuals produced by anion exchange and 
coagulation-microfiltration (Clifford, 1997). Experiments were 
performed at the University of Houston-US EPA Drinking Water Research 
Facility, a 10 ft x 40 ft customized trailer containing various unit 
processes, including ion exchange and coagulation-microfiltration, and 
a small analytical lab. The mobile research facility was set up at the 
West Mesa Pump Station in Albuquerque, NM. The mean arsenic 
concentration in the source water was 0.021 mg/L.
    Ion exchange was field tested, and the media was regenerated. This 
initial waste stream was a brine from the regeneration process. The 
brine in the ion exchange process was reused 15 times. The average 
arsenic concentration in the product was below 0.002 mg/L during the 15 
cycles. The process produced a highly concentrated spent brine, with 
arsenic concentrations reaching 26.6 mg/L. It should be noted that the 
arsenic concentration in the brine would be lower if the brine was not 
used as many times. After 6 months of storage, the arsenic 
concentration reduced to 11.3 mg/L. The arsenic was then precipitated 
out of the brine using iron, resulting in a brine with approximately 
0.037 mg/L of arsenic. The precipitated sludge was then subjected to 
the TCLP extraction procedure. The TCLP extract had an average arsenic 
concentration of 0.270 mg/L. This is below the current threshold for 
being designated a hazardous waste.
    Coagulation-microfiltration was also field tested. Arsenic removal 
to below 0.002 mg/L could be achieved; 12,000 gallons of water were 
filtered over 3 days. The backwash water, which is the process waste, 
had less than 0.5% solids. According to the TCLP Method 1311, for a 
liquid waste containing less than 0.5% solids, the liquid portion of 
the waste after filtration, is defined as the TCLP extract. About 20 
backwash samples were collected, filtered, and analyzed for arsenic. 
The average concentration in the backwash water after filtration was 
0.0026 mg/L and thus could be disposed as a nonhazardous waste. 
Additionally, the simulated sludge was subjected to the TCLP leaching 
procedure. The arsenic concentration in the TCLP extract was 0.0218 mg/
L, which is also considerably lower than the regulatory limit.
    The University of Colorado performed a series of tests of various 
arsenic treatment solid residuals using the TCLP test (Amy et al, 
1999). The arsenic treatment processes included conventional plants 
utilizing lime softening, alum and ferric chloride coagulation, 
activated alumina, and membranes. The results of this analysis for the 
conventional plant residuals are presented in Table VIII-6. The data 
indicates that all the plants would pass the current TCLP test although 
the data from the iron coagulation plant do approach the limit.

  Table VIII-6.--TCLP Results for Conventional Plant Arsenic Residuals
------------------------------------------------------------------------
                                                         TCLP extract
          Utility ID              Type of utility       Arsenic (mg/L)
------------------------------------------------------------------------
F, coagulation sludge........  Lime softening.......              0.0009
F, softening sludge..........  Lime softening.......              0.0039
F, filter sludge.............  Lime softening.......              0.0014
G............................  Lime softening.......              0.002
J............................  Lime softening.......              0.0284
L............................  Alum coagulation.....              0.0093
C............................  Fe/Mn removal........              0.0444
O............................  Iron coagulation.....              1.5596
------------------------------------------------------------------------

    Table VIII-7 is a summary of TCLP data on liquid residuals prepared 
by the University of Colorado for activated alumina regenerant and a 
reverse osmosis reject water precipitated with ferric chloride. The 
activated alumina regenerant solution was neutralized to a pH of 6, 
which caused the aluminum to precipitate and adsorb the arsenic. The 
membrane reject water was treated with ferric chloride to remove the 
arsenic and the resulting ferric hydroxide residual was tested. The 
data indicates that solid residuals generated from the alumina 
regenerant and membrane residuals would pass the TCLP test.

   Table VIII-7.--TCLP Test Results for Activated Alumina and Membrane
                                Residuals
------------------------------------------------------------------------
                                                                 TCLP
                           Sample                            extract  as
                                                                (mg/L)
------------------------------------------------------------------------
Activated Alumina Column Regenerant........................       0.0242
Membrane Filter Reject Residuals...........................       0.0179
------------------------------------------------------------------------

    All of the previous data is from residuals produced by central 
treatment. There is no TCLP data on spent activated alumina from POU or 
POE devices. The TCLP results of spent activated alumina media from POU 
and POE devices were simulated by assuming a worst-case scenario for 6-
month and one year replacement frequencies (Kempic, 2000). To determine 
the amount of arsenic that could potentially leach into the extraction 
fluid during the toxicity characteristic leaching procedure, it was 
assumed that the influent arsenic concentration was 0.050 mg/L and that 
the activated alumina column adsorbed all of the arsenic. The first 
assumption represents the upper bound for influent concentrations since 
it is the current maximum contaminant level (MCL) for arsenic. The 
second assumption means that there would be no leakage or any 
breakthrough of arsenic through the column, which is not realistic. To 
calculate the total adsorbed arsenic mass, it was assumed that the POU 
unit treated 24 liters per day. This is the upper bound consumption 
used in the replacement frequency calculations.
    Two other assumptions were made to simulate the worst-case 
scenarios. In the TCLP, the solid phase is extracted with an amount of 
extraction fluid equal to 20 times the weight of the solid phase. The 
dry media mass was used for the solid phase for this calculation rather 
the wet media mass. It was also assumed that all of the adsorbed 
arsenic would leach into the extraction fluid, which is not realistic. 
The estimates for the worst-case scenarios are provided in Table VIII-
8.

[[Page 38931]]



     Table VIII-8.--TCLP Projections for Activated Alumina Worst-Case
                               Simulations
------------------------------------------------------------------------
                                                               Max TCLP
                   Replacement frequency                     Conc.  (mg/
                                                                  L)
------------------------------------------------------------------------
POU & 6-months.............................................          2.6
POE & 6-months.............................................          0.8
POU & Annual...............................................         10.4
POE & Annual...............................................          3.2
------------------------------------------------------------------------

    The projections for three of the worst-case scenarios were below 
the TC of 5 mg/L. The worst-case maximum TCLP concentration for annual 
replacement for a POU activated alumina device was above the TC. 
However, despite this projection, activated alumina waste should be 
non-hazardous. The most unrealistic assumption was that all of the 
arsenic adsorbed onto the alumina would leach into the extraction 
fluid. The TCLP uses weak acetic acid (0.57%) at pH 5 for the 
extraction fluid. The optimal pH for arsenic adsorption onto activated 
alumina is between pH 5.5 and 6.0. Therefore, arsenic should be 
retained on the activated alumina at this pH. In fact, adsorbed arsenic 
is extremely difficult to remove under any conditions. A strong base 
(4% NaOH) is typically used to regenerate activated alumina. Arsenic is 
so strongly adsorbed to the activated alumina that only 50 to 70% of 
the arsenic is eluted during regeneration. Therefore, it is extremely 
unlikely that the spent activated alumina from POU and POE units would 
be considered hazardous.
    All of the TCLP data from solid residuals were below the current TC 
of 5 mg/L. The arsenic concentrations in TCLP extracts from alum 
coagulation, activated alumina, lime softening, iron/manganese removal, 
and coagulation-microfiltration residuals were below 0.05 mg/L, which 
is two orders of magnitude lower than the current TC regulatory level. 
The TCLP data for iron coagulation was mixed--the residuals from the 
arsenic removal plant were below 0.05 mg/L, but the residuals from 
another iron coagulation plant were above 1 mg/L. For anion exchange, 
the TCLP data on the precipitated brine stream was 0.27 mg/L. As was 
noted, this was a highly concentrated brine stream which had been used 
for fifteen regenerations. Arsenic concentrations in the precipitate 
would be lower if the brine was used for fewer regeneration cycles. 
Based on this data, EPA does not believe that drinking water treatment 
plant residuals would be classified as hazardous waste. The TCLP data 
also indicate that most residuals could meet a much lower TC regulatory 
level. EPA requests comment on whether it is appropriate to assume that 
all residuals can be disposed at a non-hazardous landfill.

IX. Costs

A. Why Does EPA Analyze the Regulatory Burden?

    EPA is responsible for issuing regulations that improve the quality 
of the nation's drinking water and reduce the risk of illness from 
exposure to harmful contaminants via drinking water supplied by public 
water systems (PWSs). As part of the regulatory development process, 
the Agency is required to analyze the regulatory cost and burden 
imposed on all regulated and affected entities and the benefits 
associated with the regulation. The Regulatory Impact Analysis (RIA) 
document is the principal summary of these analyses. Assessing the 
impacts of proposed SDWA regulations is a complex process, involving 
many analyses specified by various federal mandates. In particular, EPA 
must conduct analyses for the following mandates:
 1996 Safe Water Drinking Act (SDWA) Amendments
 Paperwork Reduction Act (PRA)
 Regulatory Flexibility Act (RFA)
 Small Business Regulatory Enforcement Fairness Act (SBREFA)
 Unfunded Mandates Reform Act (UMRA)
 Executive Order (EO) 12866, ``Regulatory Planning and Review''
 EO 12989, ``Federal Actions to Address Environmental Justice 
in Minority Populations and Low-Income Populations''
 EO 13045, ``Protection of Children from Environmental Health 
Risks and Safety Risks.''
    Executive Order 12866 describes the requirements for and content of 
the national cost-benefit analyses. Section 1412(b)(3)(C) of SDWA, as 
amended in 1996, directs EPA to seek comment on a health risk reduction 
and cost analysis (HRRCA) that will be issued with proposed MCLs. The 
HRRCA must identify quantifiable and nonquantifiable costs and health 
benefits of each MCL considered, including the incremental costs and 
benefits of each MCL considered. In addition, the HRRCA must identify 
benefits resulting from reducing co-occurring contaminants and exclude 
costs that will result from other proposed or final regulations. The 
Paperwork Reduction Act (PRA) requires federal agencies to document the 
cost and labor burden associated with data collection, recordkeeping, 
and reporting requirements of proposed regulations. The Regulatory 
Flexibility Act (RFA), as amended by the Small Business Regulatory 
Enforcement Fairness Act (SBREFA), mandates that federal agencies 
consider the impact imposed on small businesses, governments, and non-
profit organizations. The objective of these mandates is to provide 
regulatory relief to small entities affected by SDWA regulations by 
identifying alternative or lower-cost compliance options. Finally, the 
Unfunded Mandates Reform Act (UMRA) seeks to assess the burden and 
costs of federal regulations to local and State governments, while 
Executive Order 12989 on environmental justice instructs federal 
agencies to evaluate the impact of proposed regulations on minority and 
low-income populations. Executive Order 13045 requires EPA to state how 
the regulation addresses risks for children.
    An RIA attempts to estimate the possible outcomes in terms of costs 
and benefits of various levels of regulation. At the most basic level, 
an RIA is built on estimates of the distribution of arsenic occurrence 
among the various water systems, the costs of treatment technologies, 
and predictions of responses by systems above the regulatory level 
under consideration. Because actual compliance monitoring at the 
proposed MCL has not been required of all systems at the time of 
proposal development, projections are based on statistical estimates. 
EPA believes that the current estimates include appropriate 
conservative assumptions and on average actual costs are not likely to 
exceed the estimates. One conservative assumption is that equipment 
useful life is identical to financing life. The Agency has a long term 
effort in progress to better characterize how much this issue will 
affect cost estimations.
    To be complete, accurate, and consistent, these analyses should be 
based on a single, integrated set of data and information that defines 
the baseline characteristics or conditions of the regulated community 
prior to implementation of the regulation. The regulated community is 
primarily the water supply industry and State, local, and tribal 
governments. However, it is the customers of public water systems, 
especially community water systems, that ultimately incur the cost 
burden and realize the intended health benefits of these regulations. 
Therefore, the baseline study identifies and, where possible, 
quantifies the universe (e.g., characteristics of water suppliers, 
their customers, and governmental entities) to

[[Page 38932]]

be used in the regulatory impact analysis (RIA).
    The current RIA applied national occurrence information in the 
modeling effort as described earlier in section V.G. EPA requests 
comment on its analyses for developing cost projections, including 
household costs, as well as additional cost information. Most previous 
RIAs conducted for the drinking water program assumed that all the 
water going into a system was the same concentration. Actually, many 
water systems (especially those serving more than 500 people) have 
multiple points where water enters the distribution system. Each of 
these entry points generally will have a different level of arsenic. 
Consequently, water systems tend to be impacted by regulations in 
stages that increase with decreasing regulatory level. Because costs 
are spread across the entire system, individual household expenditures 
will vary according to regulatory level. Past RIAs were unable to 
incorporate this information, and for costing purposes, all entry 
points to the distribution system required treatment. The arsenic RIA 
is the first drinking water chemical RIA to incorporate monte carlo 
simulation of intra-system occurrence variability into the cost and 
benefits estimation. This simulation permits more accurate 
characterization of the relative household impacts of various 
alternatives. Several other changes have also been incorporated into 
the cost and benefit estimates for the arsenic RIA:
    Very Large Systems--Very large water systems, those serving more 
than a million people, can contribute a significant portion to 
estimates of overall costs and benefits at select regulatory levels. On 
the other hand, because there are so few of these systems and given 
that they are of complex configuration, statistically based estimates 
of arsenic occurrence (especially at low levels of arsenic incidence) 
introduce very large uncertainty into the RIA. EPA addressed this issue 
by developing individually tailored estimates through the use of 
generally available occurrence information and Information Collection 
Rule data. Estimates were provided to the utilities and they were 
offered the opportunity to correct errors in the Agency assessment. 
While these estimates are a considerable improvement over past ones, it 
is important to keep in mind that they are merely projections and that 
individual compliance costs could actually still vary by a wide margin 
depending upon rule timing, interactions with other treatment or 
capital budget priorities, regulatory commission decisions, or actual 
compliance sampling results.
    Inventory Based Modeling--Past RIAs have generally developed 
benefit and cost estimates by estimating impacts for single 
representative community water systems within a limited number of size-
based classes. Such an approach introduces a slight positive bias to 
total national cost estimates. This RIA has gone beyond the past 
approach in the modeling of community water system and non-transient 
non-community water system impacts. This RIA uses a monte carlo 
approach to simulate application of occurrence information to the 
actual SDWIS inventory. Through repeated simulations and assignments, 
the model is able to develop the most robust [statistically defensible] 
estimates of actual exposure levels and to better characterize the 
spread in household costs.

B. How Did EPA Prepare the Baseline Study?

    EPA identified baseline characteristics as the first step in 
standardizing baseline profiles and information for use across all 
Agency drinking water RIAs and related analyses. The Agency has several 
efforts underway to develop improved technical approaches for cost and 
benefit analyses, including developing characteristic engineering unit 
costs of treatment plants, assessing financial and operational 
capacity, and considering the low-cost best available treatment (BAT) 
options for small systems. Then, EPA reviewed the analytical 
procedures, and data requirements needed to conduct the analyses.
    Table IX-1 provides an overview of the overall approach for 
identifying and classifying specific baseline characteristics. This 
matrix organizes the baseline characteristics according to the various 
entities likely to be affected by SDWA regulations and the different 
categories of data analysis inputs. The affected entities include:
     State and Tribal Governments: Agencies at the State or 
local level (including certain Tribes and Alaskan Native Villages) 
responsible for implementing, administering, and enforcing drinking 
water programs, and other programs potentially affected by Federal 
drinking water mandates.
     Public Water Suppliers: Utilities and other entities that 
provide potable water to 25 or more persons, 15 or more service 
connections (includes community and transient/non-transient non-
community water systems).
     Customers: All entities that purchase drinking water from 
public water systems (including residential, commercial, industrial, 
wholesale, governmental, agricultural, and other users).
    The corresponding categories of data analysis inputs shown in Table 
IX-1 include:
    1. Technical/Operational: Characteristics relating to capital 
assets and operational processes, labor skills and training, and other 
variable inputs.
    2. Managerial/Organizational: Characteristics relating to 
ownership, control and authority, organizational structure and 
management approach.
    3. Financial/Economic: Characteristics relating to monetary 
factors, opportunity costs, and benefits.
    4. Socio-Economic/Demographic: Composition and characteristics of 
affected entities (who, where, how much) and demographic trends.
    Data to describe all the baseline conditions shown in Table IX-1 
are contained in a comprehensive EPA document designed to be applicable 
to all drinking water regulatory impact analyses, ``The Baseline 
Handbook.'' It is data from this document which is used in Chapter 4 of 
the RIA for Arsenic.
1. Use of Baseline Data
    Uses of baseline data include the following analyses:
National and Sub-National Benefits, Costs, and Economic Impact 
Analyses:
     Occurrence Analysis
     Exposure/Risk Assessment
     Model Plants/System Configuration
     Unit Engineering Cost Analysis
     Compliance Decision Tree Analysis
     Financial Analysis
     Government Implementation
     Reporting, Recordkeeping, and Monitoring Costs
     Valuation of Health Benefits
     Non-Health Benefits Assessment
     Economic Impact Assessment
Small Entity Impact Analyses:
     Small Entity Definition
     Reporting and Recordkeeping Requirements for Small 
Entities
     Financial Analysis for Small Entities
     Socio-Economic Analysis for Small Entities
     Regulatory Alternatives Analysis
Other Special Analyses:
     Health Risks to Sensitive Subpopulations
     Affordability Analyses
     Government Budgetary Effects
    These broad analytical requirements reflect the overlapping nature 
of the required analyses pursuant to the relevant statutory and 
administrative mandates. For example, various mandates, including EO 
12866, SDWA,

[[Page 38933]]

UMRA, and PRA, require national cost and benefit analyses.
2. Key Data Sources Used in the Baseline Analysis for the RIA?
    A number of different data sources were employed in the development 
of the tables included Chapter 4 of the arsenic RIA. The key data 
sources used included:

    1995 Community Water System Survey (CWSS). This database was 
compiled by EPA from a survey conducted in 1995 to profile the 
operational and financial characteristics of community water systems 
of all source, size, and ownership types.
    WATER STATS, The Water Utility Database. This database was 
compiled by the American Water Works Association from a 1996 survey 
of its member utilities. Data on water system operations and 
finances were collected in two stages. The first stage involved a 
comprehensive census of the largest water utilities (i.e., those 
serving 50,000 or more persons). A second stage data collection 
involved a statistical sample of smaller water utilities.
    Safe Drinking Water Information System (SDWIS). This database 
serves as the U.S. EPA's comprehensive database of public water 
system regulatory compliance and violation information. SDWIS 
contains the Agency's inventory of all public water supplies, both 
community and noncommunity systems and the populations they serve.
    Survey on State Program Staffing/Funding for FY-97. The 
Association of State Drinking Water Administrators (ASDWA) conducted 
a survey of State drinking water programs to solicit estimates on 
the number of staff (i.e., full-time equivalents, FTEs) involved in 
drinking water regulatory implementation and enforcement activities 
by program area, as well as estimates of drinking water program 
revenues/funding and expenditures by major account categories.
    1990 Census of Population. Data from the 1990 Census of 
Population was used in conjunction with water system data to develop 
estimates for various demographic characteristics of households and 
communities served by public water systems.


                    Table IX-1.--Summary of General Baseline Categories of Affected Entities
----------------------------------------------------------------------------------------------------------------
                                                             Baseline characteristics
                                 -------------------------------------------------------------------------------
         Affected entity            1: Technical &      2: Managerial &      3: Economic &    4: Socioeconomic &
                                      operational       organizational         financial          demographic
----------------------------------------------------------------------------------------------------------------
A: State Government.............  A1.1  PWS           A2.1  Program       A3.1  Program       A4.1  State PWS
                                   Inspections &       Staffing.           Expenditures.       Profile.
                                   Sanitary Surveys.  A2.2  Laboratory    A3.2  Program
                                                       Capacity/           Funding/Revenues.
                                                       Facilities.
                                                      A2.3  Division of
                                                       Authority/
                                                       Jurisdiction.
B: Public Water Suppliers.......  B1.1  Water         B2.1  Ownership/    B3.1  Operating     B4.1  PWS Type.
                                   Sources/Intakes.    Organizational      Expenses.          B4.2  PWS Size/
                                  B1.2  Source         Structure.         B3.2  Operating      Customer Base.
                                   Contamination/     B2.2  Plant          Revenues.          B4.3  PWS Source
                                   Protection.         Operation/         B3.3  Non-           Water.
                                  B1.3  Physical       Operators.          Operating          B4.4  Geographic
                                   Configuration.                          Expenses.           Location.
                                  B1.4  Plant                             B3.4  Assets &
                                   Condition.                              Liabilities.
                                  B1.5  Plant Flow/                       B3.5  Rate
                                   Capacity.                               Structures/User
                                  B1.6  Treatment/                         Burden.
                                   Waste Processes                        B3.6  Capital
                                   In-Place.                               Investment
                                  B1.7  Storage                            Expenditure.
                                   Capacity.
                                  B1.8  Distribution
                                   System.
                                  B1.9  Residence
                                   Time.
                                  B1.1  Monitoring/
                                   Laboratory.
C: Customers....................  C1.1  POU/POE       C2.1  Alternative   C3.1  Residential   C4.1  Population
                                   Systems In Use.     Water Use.          Income.             Profile.
                                                      C2.2  Public        C3.2  Nonresidenti  C4.2  Customer
                                                       Attitudes/          al Income.          Water Use.
                                                       Perceptions.       C3.3  Residential
                                                                           Water Costs.
                                                                          C3.4  Nonresidenti
                                                                           al Water Costs.
                                                                          C3.5  Cost of
                                                                           Drinking Water
                                                                           Alternatives.
                                                                          C3.6  Medical
                                                                           Costs.
                                                                          C3.7  Non-Medical
                                                                           Costs.
                                                                          C3.8  Community
                                                                           Financial
                                                                           Information.
----------------------------------------------------------------------------------------------------------------

C. How Were Very Large System Costs Derived?

    EPA must conduct a thorough cost-benefit analysis, and provide 
comprehensive, informative, and understandable information to the 
public about its regulatory efforts. As part of these analyses, EPA 
evaluated the regulatory costs of compliance for very large systems, 
who would be subject to the new arsenic drinking water regulation. The 
nation's 25 largest drinking water systems (i.e., those serving a 
million people or more) supply approximately 38 million people and 
generally account for about 15 to 20 percent of all compliance-related 
costs. Accurately determining these costs for future regulations is 
critical. As a result, EPA has developed compliance cost estimates for 
the arsenic and radon regulations for each individual system that 
serves greater than 1 million persons. These cost estimates help EPA to 
more accurately assess the cost impacts and benefits of the arsenic 
regulation. The estimates also help the Agency identify lower cost 
regulatory options and better understand current water systems' 
capabilities and constraints.
    The system costs were calculated for the 24 public water systems 
that serve a retail population greater than 1 million persons and one 
public water

[[Page 38934]]

system that serves a wholesale population of 16 million persons. Table 
IX-2 lists these 25 public water systems. The distinguishing 
characteristics of these very large systems include:
    (1) A large number of entry points from diverse sources;
    (2) mixed (i.e., ground and surface) sources;
    (3) Occurrence not conducive to mathematical modeling;
    (4) Significant levels of wholesaling;
    (5) Sophisticated in-place treatment;
    (6) Retrofit costs dramatically influenced by site-specific 
factors; and
    (7) Large amounts of waste management and disposal which can 
contribute substantial costs.

                 Table IX-2.--List of Large Water Systems That Serve More Than 1 Million People
----------------------------------------------------------------------------------------------------------------
                                                        PWS ID #                            Utility name
----------------------------------------------------------------------------------------------------------------
 1...................................  AZ0407025                                   Phoenix Municipal Water
                                                                                    System.
 2...................................  CA0110005                                   East Bay Municipal Utility
                                                                                    District.
 3...................................  CA1910067                                   Los Angeles--City Dept. of
                                                                                    Water and Power.
 4...................................  CA1910087                                   Metropolitan Water District
                                                                                    of Southern California.
 5...................................  CA3710020                                   San Diego--City of.
 6...................................  CA3810001                                   San Francisco Water
                                                                                    Department.
 7...................................  CA4310011                                   San Jose Water Company.
 8...................................  CO0116001                                   Denver Water Board.
 9...................................  FL4130871                                   Miami-Dade Water And Sewer
                                                                                    Authority--Main System.
 10..................................  GA1210001                                   City of Atlanta.
 11..................................  IL0316000                                   City of Chicago.
 12..................................  MA6000000                                   Massachusetts Water Resource
                                                                                    Authority.
 13..................................  MD0150005                                   Washington Suburban
                                                                                    Sanitation Commission.
 14..................................  MD0300002                                   Baltimore City.
 15..................................  MI0001800                                   City of Detroit.
 16..................................  MO6010716                                   St. Louis County Water
                                                                                    County.
 17..................................  NY5110526                                   Suffolk County Water
                                                                                    Authority.
 18..................................  NY7003493                                   New York City Aqueduct
                                                                                    System.
 19..................................  OH1800311                                   City of Cleveland.
 20..................................  PA1510001                                   Philadelphia Water
                                                                                    Department.
 21..................................  PR0002591                                   San Juan Metropolitano.
 22..................................  TX0570004                                   Dallas Water Utility.
 23..................................  TX1010013                                   City of Houston--Public Works
                                                                                    Department.
 24..................................  TX150018                                    San Antonio Water System.
 25..................................  WA5377050                                   Seattle Public Utilities.
----------------------------------------------------------------------------------------------------------------

    Generic models cannot incorporate all of these considerations; 
therefore, in-depth characterizations and cost analyses were developed 
utilizing several existing databases and surveys.
    The profile for each system contains information such as design and 
average daily flows, treatment facility diagrams, chemical feed 
processes, water quality parameters, system layouts, and intake and 
aquifer locations. System and treatment data were obtained from the 
following sources:
    (1) The Information Collection Rule (1997);
    (2) The Community Water Supply Survey (1995);
    (3) The Association of Metropolitan Water Agencies Survey (1998);
    (4) The Safe Drinking Water Information System (SDWIS); and
    (5) The American Water Works Association WATERSTATS Survey (1997).
    While these sources contained much of the information necessary to 
perform cost analyses, the Agency was still missing some of the 
detailed arsenic occurrence data in these large water systems. Where 
major gaps existed, especially in groundwater systems, occurrence data 
obtained from the States of Texas, California, and Arizona, the 
Metropolitan Water District of Southern California Arsenic Study 
(1993), the National Inorganic and Radionuclides Study (EPA, 1984), and 
utilities were used. Based on data from the studies, detailed costs 
estimates were derived for each of the very large water systems.
    Cost estimates were generated for each system at several MCL 
options. The total capital costs and operational and maintenance (O & 
M) costs were calculated using the profile information gathered on each 
system, conceptual designs (i.e., vendor estimates and RS Means), and 
modified EPA cost models (i.e., Water and WaterCost models). The models 
were modified based on the general cost assumptions developed in the 
Phase I Water Treatment Cost Upgrades (EPA, 1998).
    Preliminary cost estimates were sent to all of the systems for 
their review. Approximately 30% of the systems responded by submitting 
revised estimates and/or detailed arsenic occurrence data. Based on the 
information received, EPA revised the cost estimates for those systems. 
Based on the results, the majority of the very large systems will not 
have capital or O&M expenditures for complying with a MCL of 5 
g/L (Table IX-3). More detailed costs estimates for each very 
large water system can be found in the water docket.

Table IX-3.--Total Annual Costs for Large Systems for (Serving More Than
                            1 Million People)
------------------------------------------------------------------------
                                                Number
         MCL option (g/L)             systems         Cost
                                               treating     [$millions]
----------------------------------------------------------------\1\-----
3..........................................            3         $16-18
5..........................................            3          11-12
10.........................................            3       6.6-7.47
                  20                                   3       2.6-2.7
------------------------------------------------------------------------
\1\ The lower number shows costs annualized at 3%; the higher number
  shows costs annualized at 7% capital costs. The 7% rate represents the
  standard discount rate preferred by OMB for benefit-cost analyses of
  government programs and regulations.

D. How Did EPA Develop Cost Estimates?

    EPA developed national cost estimates by using the occurrence data, 
unit cost curves, and a decision tree. The occurrence data provides a 
measure of the number of systems that would need to install treatment 
in each size

[[Page 38935]]

category (the occurrence data was described in Section V). The unit 
cost curves provide a measure of how much a technology will cost to 
install. Unit cost curves are continuous functions; they are a function 
of system size and provide an estimated cost for all design and average 
flows. The costs for a treatment train for the average flow in each 
size category were given previously in Table VIII-3. The unit cost 
curves can be found in ``Technologies and Costs for the Removal of 
Arsenic From Drinking Water'' (US EPA, 1999i).
    EPA then developed a decision tree, which is a prediction of what 
treatment technology trains facilities would likely install to comply 
with options considered for the revised arsenic standard. A brief 
discussion of this decision tree follows. A copy of the full 300+ page 
flowchart and supporting documentation can be found in ``Decision Tree 
for the Arsenic Rulemaking Process'' (US EPA, 1999d). The following 
figure is a brief representation of this flowchart. As shown in the 
flowchart, EPA considered the impact of (1) MCL option and influent 
arsenic concentration; (2) system size; (3) regional effects (water 
scarcity); (4) source water type (that is, ground water or surface 
water); (5) existing treatment in-place; (6) waste disposal issues and 
costs; and (7) co-occurrence of iron and sulfate, to estimate what 
systems are likely to install.
    Ultimately, the decision tree was expressed in decision matrices, 
in which EPA assigned probabilities as to how often each of the 
treatment trains in Table VIII-2 will likely be used. EPA developed a 
different decision matrix for the eight system size categories, for 
three different removal efficiencies (50%, 50-90% and >90%), and for 
two source waters (ground and surface). In general, to the extent 
possible (e.g., based on source water quality), EPA assumed that 
systems would employ the least-cost technology that can meet the MCL 
option.

BILLING CODE 6560-50-P

[[Page 38936]]

[GRAPHIC] [TIFF OMITTED] TP22JN00.001

BILLING CODE 6560-50-C

[[Page 38937]]

    MCL option. EPA developed a decision tree that accounted for 
treatment technology limitations, and only assigned non-zero 
probabilities in the matrices to those technologies capable of reaching 
each MCL option. The maximum removal percentages are given in Table 
VIII-1. For instance, since greensand filtration is only assumed 
capable of removing 50% of the influent arsenic, for an influent level 
of 20 g/L, the technology is assumed to be capable of only 
producing product water with 10 g/L of arsenic. Therefore, for 
an MCL option of 5 g/L, no usage was assumed for greensand 
filtration at a 20 g/L level of influent arsenic.
    System size. The decision tree also depends on system size. For 
instance, small systems are assumed to operate activated alumina on a 
throw-away basis, and thus the probability of using a treatment train 
that employs on-site regeneration is assumed to be zero. The converse 
is true for large systems; non-zero probabilities are assumed only for 
those trains that employ regeneration on-site.
    Water scarcity. Water scarcity was also taken under consideration 
when developing the decision tree. It was assumed that this issue would 
adversely affect the selection of reverse osmosis, since the technology 
rejects a significant portion of the influent water. However, the costs 
for reverse osmosis treatment trains are much higher than others (refer 
to Table VIII-3), and systems would likely opt for other, less 
expensive, treatment options. For the range of MCL options considered, 
it was assumed that ion exchange would be capable of delivering the 
required removal efficiencies. Thus, water scarcity, though considered 
in the decision tree, did not affect percentages assigned to reverse 
osmosis.
    Source water type. Source water type is also a factor in the 
decision tree. It affects the unit cost curves; one set of curves were 
developed for surface water, and another was developed for ground 
water. The treatment-in-place data and co-occurrence data (as shown 
below) are sorted by source water type. Also, certain technologies are 
considered appropriate for one source water type, but not the other. 
For instance, greensand filtration is considered relevant only for 
ground waters.
    Existing treatment in-place. Treatments that may already exist at 
facilities were taken into account in the decision tree. It was assumed 
that systems would need to pre-oxidize, if they weren't doing so 
already. Table IX-4 shows the number of systems that were assumed to 
require addition of pre-oxidation (Source: US EPA,1999e).

            Table IX-4.--Systems Needing To Add Pre-Oxidation
------------------------------------------------------------------------
                                                 Percent of   Percent of
                                                   ground      surface
                  System size                      water        water
                                                  systems      systems
------------------------------------------------------------------------
25-100........................................           54            9
101-500.......................................           30            4
501-1K........................................           24            0
1,001-3.3K....................................           24            0
3,301-10K.....................................           27            3
10,001-50K....................................           13            1
50,001-100K...................................           41            2
100,001-1 M...................................           16            0
------------------------------------------------------------------------

    It was also assumed that those systems that had coagulation/
filtration in place, or lime softening in place, would modify those 
treatments to optimize for arsenic removal, since it is a relatively 
inexpensive option. The percent of systems with these treatments in 
place is given in Table IX-5 (Source: US EPA,1999e). However, for 
higher removals (>90%), it was assumed that only half of the systems 
would be able to achieve the desired removal with a modification. For 
those systems, an additional cost of a polishing step, such as ion 
exchange, was added.

             Table IX-5.--Percent of Systems With Coagulation-Filtration and Lime-Softening in Place
----------------------------------------------------------------------------------------------------------------
                                                    Percent of      Percent of      Percent of      Percent of
                                                   ground water    surface water   ground water    surface water
                   System size                     systems with    systems with    systems with    systems with
                                                    CF in place     CF in place     LS in place     LS in place
----------------------------------------------------------------------------------------------------------------
25-100..........................................               2              22               3               4
101-500.........................................               4              53               3               9
501-1K..........................................               2              73               2              19
1,001-3.3K......................................               3              76               3              16
3,301-10K.......................................               8              85               3               7
10,001-50K......................................               4              92               5               8
50,001-100K.....................................               4              85               3               5
100,001-1 M.....................................               5              94              10               5
----------------------------------------------------------------------------------------------------------------

    Waste disposal issues and costs. Waste disposal of arsenic 
contaminated sludges and brines was also factored into the decision 
tree, and waste costs were added to the treatment trains. The waste 
disposal options for each of the technologies considered are given in 
Table IX-6. For ion exchange and activated alumina, it was assumed that 
the waste streams would be too concentrated to discharge directly. For 
these technologies, it was assumed that some of the smallest systems 
would be able to take advantage of evaporation ponds, but that this 
option would be cost prohibitive in medium and large systems. It was 
assumed that most systems would opt for either chemical precipitation 
or discharge to a sanitary sewer. EPA also assumed that systems would 
dispose of spent activated alumina media in non-hazardous landfills. 
Costs for reverse osmosis are prohibitive (In Table VIII-3, Annual 
Costs of Treatment Trains, compare lines 11, 12, and 13 against other 
technologies), but if used, EPA assumed the relatively large amount of 
reject water would be discharged directly (because it would not be as 
concentrated as ion exchange and activated alumina waste streams), to a 
sanitary sewer or by chemical precipitation. For coagulation assisted 
microfiltration, modified coagulation filtration, and modified lime 
softening, EPA assumed the waste would be discharged to non-hazardous 
landfills after the sludge is mechanically or non-mechanically 
dewatered. For greensand filtration, it was assumed that the spent 
media would be disposed of in a non-hazardous landfill.

[[Page 38938]]



                                                           Table IX-6.--Waste Disposal Options
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         POTW waste                    Non-haz       Direct       Chemical                    Non-mech
                    Treatment tech                        disposal      Evap pond     landfill      discharge      precip     Mech dewater     dewater
--------------------------------------------------------------------------------------------------------------------------------------------------------
Ion Exchange..........................................                                                
Activated Alumina.....................................                                         
Reverse Osmosis.......................................                                                
Coag Assisted Micro-filtration........................                                                                            
Greensand.............................................                                  
Modify CF.............................................                                                                            
Modify LS.............................................                                                                            
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Co-occurrence of iron and sulfate. EPA also factored into the 
decision tree co-occurrence data on iron and sulfate (shown in Tables 
IX-7 to IX-10, Source: US EPA,1999f ). Co-occurrence of sulfate in 
water adversely affects the performance of ion exchange, and increases 
operation and maintenance costs. Three sulfate-level treatment trains 
were costed for ion exchange: one low-level, one mid-level and one 
high-level. The percentages in Tables IX-7 to IX-8 were used as 
ceilings in national cost estimates and limited the number of systems 
that could be placed in the decision matrices in the low-level and mid-
level sulfate ranges. For example, the co-occurrence data shows that 
the maximum number of systems that can be costed at the low-level 
sulfate treatment train for an influent level of arsenic between 10 and 
20 g/L is 35%. If more systems were to be placed in the 
decision matrices under ion exchange, no more than 39% were assumed to 
face a sulfate level between 25 and 120 mg/L. Any more systems assigned 
to ion exchange in the decision matrices were assumed to face high 
sulfate levels.

             Table IX-7.--Ground Water: Arsenic and Sulfate
------------------------------------------------------------------------
                                      Likelihood of sulfate  (percent)
         Influent arsenic         --------------------------------------
                                     25 mg/L    25-120 mg/L   >120 mg/L
------------------------------------------------------------------------
10 g/L..................           48           33           19
10-20 g/L...............           35           39           26
>20 g/L.................           33           38           30
------------------------------------------------------------------------


             Table IX-8.--Arsenic Water: Arsenic and Sulfate
------------------------------------------------------------------------
                                      Likelihood of sulfate  (percent)
         Influent arsenic         --------------------------------------
                                     25 mg/L    25-120 mg/L   >120 mg/L
------------------------------------------------------------------------
10 g/L..................           28           32           40
10-20 g/L...............           20           30           51
>20 g/L.................           12           28           60
------------------------------------------------------------------------


               Table IX-9.--Ground Water: Arsenic and Iron
------------------------------------------------------------------------
                                                  Likelihood of sulfate
                                                        (percent)
                                               -------------------------
               Influent arsenic                 300 300 g/L        m>g/L
 
------------------------------------------------------------------------
10 g/L...............................           82           18
10-20 g/L............................           81           19
>20 g/L..............................           71           29
------------------------------------------------------------------------


              Table IX-10.--Surface Water: Arsenic and Iron
------------------------------------------------------------------------
                                                  Likelihood of sulfate
                                                        (percent)
                                               -------------------------
               Influent arsenic                 300 300 g/L        m>g/L
 
------------------------------------------------------------------------
10 g/L...............................           91            9
10-20 g/L............................           92            8
>20 g/L..............................           90           10
------------------------------------------------------------------------

    Co-occurrence of iron in water improves the performance of 
greensand filtration. Greensand is relatively inexpensive for small 
systems to use, but not as effective as other treatment technologies. 
It was assumed that systems would opt for greensand filtration only if 
the level of iron was greater than 300 g/L. EPA used the co-
occurrence data in Tables IX-9 to IX-10 to determine the ceiling on the 
number of systems that could use greensand filtration in the decision 
matrices.

E. What Are the National Treatment Costs of Different MCL Options?

    Under the proposed option of 5 g/L, the Agency estimates 
that annual treatment costs to community water systems will be $374 
million per year. If required to treat at the proposed level,

[[Page 38939]]

treatment costs to non-community non-transient systems would be $15 
million per year. National annual costs for the MCL options considered 
(3, 5, 10, and 20 g/L) are provided in Table IX-11.

                                  Table IX-11.--National Annual Treatment Costs
                                              [Dollars in millions]
----------------------------------------------------------------------------------------------------------------
                                                                                   Non-community       Total
                   MCL option  (g/L)                        Community     Non-transient     treatment
                                                                   water systems      systems          costs
----------------------------------------------------------------------------------------------------------------
3...............................................................            $639             $25            $664
5...............................................................             374              15             389
10..............................................................             160               6             166
20..............................................................              59               2              61
----------------------------------------------------------------------------------------------------------------

    Total annual costs per household are given in Table IX-12. Due to 
economies of scale, costs per household are higher in the smaller size 
categories, and lower in the larger size categories. For the proposed 
option of 0.005 g/L, costs are expected to be $364 per 
household for systems serving 25-100 people, and $254 per household for 
systems serving 101-500 people. Costs per households in systems larger 
than those are substantially lower: from $104 to $21 per household. 
Costs per household do not vary dramatically across MCL options. This 
is because of the fact that once a system installs a treatment 
technology to meet an MCL target, costs do not vary significantly based 
upon the removal efficiency it will be operated under. Costs are, 
however, somewhat lower at less stringent MCL options. This is because 
it was assumed that some systems would blend water at these options, 
and treat only a portion of the flow.

                                 Table IX-12.--Total Annual Costs per Household
                                                    [Dollars]
----------------------------------------------------------------------------------------------------------------
                                                                                  10 g/  20 g/
                   System size                    3 g/L  5 g/L         L               L
----------------------------------------------------------------------------------------------------------------
25-100..........................................            $368            $364            $357            $349
101-500.........................................             259             254             246             238
501-1K..........................................             106             104              98              93
1K-3.3K.........................................              64              60              57              52
3.3K-10K........................................              44              41              37              33
10K-50K.........................................              36              33              29              25
50K-100K........................................              30              27              23              19
100K-1M.........................................              23              21              18              15
----------------------------------------------------------------------------------------------------------------

    Incremental costs are given in Tables IX-13 and IX-14. Incremental 
costs refer to the dollars that must be spent to obtain the next, more 
stringent, level of control. The national and household costs under 20 
g/L refer to the amount that must be spent to reach 20 
g/L starting from the baseline of 50 g/L. The dollar 
value under 10 g/L represents the cost differential between 20 
g/L and 10 g/L. The values under 5 g/L and 3 
g/L were derived similarly.

                                 Table IX-13.--Incremental National Annual Costs
                                              [Dollars in millions]
----------------------------------------------------------------------------------------------------------------
                                                                                   Non-community
                   MCL option  (g/L)                        Community     non-transient       Total
                                                                   water systems   water systems
----------------------------------------------------------------------------------------------------------------
20..............................................................             $59              $2             $61
10..............................................................             101               4             105
5...............................................................             214               9             223
3...............................................................             265              19             275
----------------------------------------------------------------------------------------------------------------


                              Table IX-14.--Incremental Annual Costs per Household
                                                    [Dollars]
----------------------------------------------------------------------------------------------------------------
                                                  20 g/  10 g/
                   System size                           L               L        5 g/L  3 g/L
----------------------------------------------------------------------------------------------------------------
25-100..........................................            $349              $8              $7              $4
101-500.........................................             238               8               8               5
501-1K..........................................              93               5               6               2
1K-3.3K.........................................              52               5               3               4
3.3K-10K........................................              33               4               4               3

[[Page 38940]]

 
10K-50K.........................................              25               4               4               3
50K-100K........................................              19               4               4               3
100K-1M.........................................              15               3               3               2
----------------------------------------------------------------------------------------------------------------

    In the process of analyzing treatment technologies and developing 
cost estimates, EPA held several meetings with stakeholders to obtain 
input on assumptions made. Several of the key assumptions agreed to by 
stakeholders are given below.
1. Assumptions Affecting the Development of the Decision Tree
     EPA assumed that ion exchange usage would be prohibited 
above 120 mg/L of sulfate and 500 mg/L of TDS.
     EPA assumed that greensand filtration would be used only 
if iron in the raw water was above 300 g/L.
     EPA assumed that systems would pre-oxidize, when existing 
chlorination or other oxidants are not already present.
     EPA assumed that systems would not likely use POE-RO nor 
POE-IX because of corrosion control problems. Also, with IX, if the 
resin is not replaced and/or regenerated on time, there is a potential 
for arsenic peaking. EPA assumed that systems will most likely use POE-
AA.
     The breakthrough issue also exists with POU-IX. POU-AA has 
the advantage of a longer run length. EPA assumed that systems would 
use either POU-AA or POU-RO.
2. Assumptions Affecting Unit Cost Curves
     There are significant safety and operating efficiency 
risks to small systems when adjusting downward. This pH adjustment 
would require much more oversight than most small systems will have. 
EPA, in calculating unit costs for activate alumina assumed that 
systems would not adjust pH downward; thus, AA will be operated at a 
sub-optimal pH.
     There is a danger of operating technologies such as ion 
exchange near breakthrough. EPA incorporated a safety factor, and used 
80% of the MCL as the target when calculating costs for all 
technologies.
     EPA assumed that small systems would not regenerate 
Activated Alumina on site--AA will likely be operated on a ``throw-
away'' basis.
     For modifying coagulation/filtration, EPA considered the 
cost of a new chemical feed system when switching to iron. EPA costed 
out switching coagulants for high removals. For lower removals, EPA 
costed out optimizing alum usage.
     EPA assumed 75% for RO recovery.
     For Activated Alumina, EPA assumed that there will not be 
any systems with raw water in the optimal range for arsenic removal (pH 
between 5.5-6.0).
     For iron-coagulation-micro-filtration EPA assumed systems 
would apply a stronger iron dose rather than adjusting to optimum pH.
     For ion exchange, one or more regenerations per day is not 
problematic. Regeneration in Ion Exchange can be done automatically. 
EPA examined cost models on regeneration frequency, volume of waste 
generated and considered computer-automation for regeneration.

X. Benefits of Arsenic Reduction

    The benefits associated with reductions of arsenic in drinking 
water arise from a reduction in the risk of adverse human health 
effects, and a corresponding decrease in the number of expected cases 
and premature deaths of people experiencing these effects. The various 
adverse health effects associated with arsenic are known with different 
levels of certainty. Presently some can be quantified and some cannot. 
The best characterized benefits can be both quantified and monetized 
(i.e., a dollar value is attached to the expected decrease in number of 
cases), while other benefits may be only known well enough to describe. 
The latter are known as qualitative benefits. The Safe Drinking Water 
Act (SDWA) amendments of 1996 require that EPA fully consider both 
quantifiable and non-quantifiable benefits that result from drinking 
water regulations.
    The first step in the benefits evaluation process is to consider 
the adverse health effects that may be expected to decrease with a 
reduction in the concentrations of arsenic in drinking water. Arsenic 
has many health effects, both cancer and non-cancer. Section III. 
discusses these health effects.
    As discussed in section VIII.A., treatment for arsenic removal may 
add or remove other contaminants. Using chlorine or other oxidants may 
increase risk from disinfection by-products. On the other hand, 
treatments put in place for arsenic may incidentally reduce the risk 
from other co-occurring contaminants.

A. Monetized Benefits of Avoiding Bladder Cancer

    Reducing arsenic levels in tap water will reduce the risks of 
suffering the adverse health effects described in the previous 
sections. In 1999 the National Research Council examined several risk 
distributions for male bladder cancer in 42 villages in Taiwan with 
arsenic ranging from 10 to 934 g/L, grouping arsenic exposure 
by village. Previous scientific studies analyzed risk using less 
specific exposure categories, which can obscure ``the true shape of the 
dose response curve (NRC 1999, page 273).'' Risk assessments for other 
adverse health effects have not been as thoroughly addressed.
    To monetize bladder cancer benefits, EPA calculated the number of 
cases potentially avoided based on the NRC bladder cancer risk 
analyses. The cases are evaluated in terms of the economic benefits 
associated with avoiding the cancer cases.
    In addition to the monetized benefits of avoiding bladder cancer, 
EPA has chosen to monetize the potential benefits of avoided lung 
cancer, using a ``What If'' analysis based on statements in the NRC 
report (see section X.B for applying the ``what-if'' scenario to lung 
cancer).
1. Risk Reductions: The Analytic Approach
    EPA applied the 1999 NRC bladder cancer risk assessment to U.S. 
males and females. The following sections explain how we calculated 
risk reductions for populations exposed to MCL options of 3 g/
L and above. The approach for this analysis included five components. 
First, EPA used data from the recent EPA water consumption study. This 
study is described in section X.A.2. Second, Monte Carlo simulations 
(section X.A.3) were used to develop relative exposure factors (section 
X.A.4). Third, arsenic occurrence estimates were used to identify the 
population exposed to levels above 3 g/L. Fourth, NRC risk 
distributions were chosen for

[[Page 38941]]

the analysis. Fifth, EPA developed estimates of the risks faced by 
exposed populations using Monte Carlo simulations, using the relative 
exposure factors, occurrence, and NRC risk distributions mentioned 
above. These components of the analysis are described in the following 
sections.
2. Water Consumption
    EPA recently updated its estimates of personal (per capita) daily 
average estimates of water consumption (``Estimated per Capita Water 
Consumption in the United States,'' EPA 2000a). The estimates used data 
from the combined 1994, 1995, and 1996 Continuing Survey of Food 
Intakes by Individuals (CSFII), conducted by the U.S. Department of 
Agriculture (USDA). The CSFII is a complex, multistage area probability 
sample of the entire U.S. and is conducted to survey the food and 
beverage intake of the U.S. Estimates of water consumed include direct 
water, indirect water and total water (Table X-1). ``Direct'' water is 
tap water consumed directly as a beverage. ``Indirect'' water is 
defined as water added to foods and beverages during final preparation 
at home or by food service establishments such as school cafeterias and 
restaurants. For the purpose of the report, indirect water did not 
include ``intrinsic'' water which consists of water found naturally in 
foods (biological water) and water added by commercial food and 
beverage manufactures (commercial water). ``Total'' water refers to 
combined direct and indirect water consumption.

                                      Table X-1.--Source of Water Consumed
----------------------------------------------------------------------------------------------------------------
                                                                                 Indirect (from
                            Source                                  Direct          food and      Bottled water
                                                                  (drinking)       beverages)
----------------------------------------------------------------------------------------------------------------
Community Tap................................................               X                X
Well Tap.....................................................               X                X
Total........................................................               X                X                X
----------------------------------------------------------------------------------------------------------------

    Per capita water consumption estimates are reported by source. 
Sources include community/tap water, bottled water, and water from 
other sources, including water from household wells and rain cisterns, 
and household and public springs. For each source, the mean and 
percentiles of the distribution of average daily per capita consumption 
are reported. The estimates are based on an average of 2 days of 
reported consumption by survey respondents.
    The estimated mean daily average per capita consumption of 
community/tap water by individuals in the U.S. population is 1 liter/
person/day. For total water, which includes bottled water, the 
estimated mean daily average per capita consumption is 1.2 liters per/
person/day. These estimates of water consumption are based on a sample 
of 15,303 individuals in the 50 States and the District of Columbia. 
The sample was selected to represent the entire population of the U.S. 
based on 1990 census data.
    The estimated 90th percentile of the empirical distribution of 
daily average per capita consumption of community/tap water for the 
U.S. population is 2.1 liters/person/day; the corresponding number for 
daily average per capita consumption of total water is 2.3 liters/
person/day. In other words, current consumption data indicate that 90 
percent of the U.S. population consumes up to approximately 2 liters/
person/day, which is the amount many federal agencies use as a standard 
consumption value.
    Water consumption estimates for selected subpopulations in the U.S. 
are described in the analysis, including per capita water consumption 
by source for gender, region, age categories, economic status, race, 
and residential status and separately for pregnant women, lactating 
women, and women in childbearing years. The water consumption estimates 
by age were used in the computation of the relative exposure factors 
discussed in the section X.A.4.
    These water consumption numbers differ somewhat from previous 
estimates reported in earlier studies. The mean per capita daily intake 
of total tap water, as estimated from the 1977-78 USDA's Nationwide 
Food Consumption Survey, was 1.193 liters/person/day (reported by 
Ershow and Cantor in 1989). Based on the 1977-78 study, the estimated 
percentile corresponding to 2 liters per day consumed is the 88th.
3. Monte Carlo Analysis
    Monte Carlo analysis is a technique for analyzing problems where 
there are a large number of combinations of input values that are too 
large to calculate for every possible result. A random number generator 
is used to generate numbers that correspond to assumptions about the 
distribution or likelihood of various input values. For each set of 
random input values a single outcome is calculated. As the simulation 
runs, the outcome is recalculated for each new set of input values and 
continues until a stopping criterion is reached. The accuracy of this 
technique, like other statistical techniques, depends on the accuracy 
of the underlying assumptions about the distribution of input values; 
it does not resolve the uncertainty behind the assumptions. For the 
risk distributions calculated in this report, the simulations were 
carried out 2,000 times. For each simulation, a relative exposure 
factor, occurrence estimate, and individual risk estimate were 
calculated. These calculations resulted in estimates of the risks faced 
by populations exposed to arsenic concentrations in their drinking 
water. The underlying risk distribution are described in the following 
sections.
4. Relative Exposure Factors
    EPA used models to integrate the new drinking water consumption 
study information into the benefits analysis. We used distributions for 
both community/tap water and total water consumption because the 
community water/tap water estimates may underestimate actual tap water 
consumption. In this analysis, we combined the water consumption data 
with data on population weight from the U.S. Census. The weight data 
included a mean and a distribution of weight for male and females on a 
year-to-year basis throughout a lifetime. Monte Carlo analysis 
generated male and female relative exposure factors (REFs) for each of 
the broad age categories used in the water consumption study. Lifetime 
male and female relative exposure factors were then estimated, where 
the factors show the sensitivity of exposure to an individual weighing 
70 kilograms and consuming 2 liters of water per day. These life-long 
REFs can be directly multiplied by the average drinking water 
consumption to provide estimates of individual lifetime consumption

[[Page 38942]]

practices. The REFs provide a means to incorporate information on 
various age groups, for example children, into the analysis, as weight 
and water consumption vary among age groups. The means and variances of 
the REFs derived from this analysis were: for community water 
consumption (0.60, 0.37 males; 0.64, 0.36 females), for total water 
consumption (0.73, 0.39 males; 0.79, 0.37 females).
5. NRC Risk Distributions
    While the NRC's work did not constitute a formal risk analysis, 
they did examine many statistical issues (e.g., measurement errors, 
age-specific probabilities, body weight, water consumption rate, 
comparison populations, mortality rates, choice of model) and provided 
a starting point for additional EPA analyses. The report noted that 
``poor nutrition, low selenium concentrations in Taiwan, genetic and 
cultural characteristics, and arsenic intake from food'' were not 
accounted for in their analysis (NRC, 1999, pg. 295).
    In its 1999 report, ``Arsenic in Drinking Water,'' the NRC analyzed 
bladder cancer risks using data from Taiwan. In addition, NRC examined 
evidence from human epidemiological studies in Chile and Argentina, and 
concluded that risks of bladder and lung cancer were comparable to 
those ``in Taiwan at comparable levels of exposure (NRC 1999, page 
7).'' The NRC also examined the implications of applying different 
mathematical procedures to the newly available Taiwanese data for the 
purpose of characterizing bladder cancer risk. These risk distributions 
are based on bladder cancer mortality data in Taiwan, in a section of 
Taiwan where arsenic concentrations in the water are very high by 
comparison to those in the U.S. It is also an area of very low incomes 
and poor diets, and the availability and quality of medical care is not 
of high quality, by U.S. standards. In its estimate of bladder cancer 
risk, the Agency assumed that within the Taiwanese study area, the risk 
of contracting bladder cancer was relatively close to the risk of dying 
from bladder cancer (that is, that the bladder cancer incidence rate 
was equal to the bladder cancer mortality rate). At the time the study 
data were collected the chances of surviving were probably poor for 
individuals diagnosed with bladder cancer. We do not have data, 
however, on the rates of survival for bladder cancer in the Taiwanese 
villages in the study and at the time of data collection. We do know 
that the relative survival rates for bladder cancer in developing 
countries overall ranged from 23.5% to 66.1% in 1982-1992 (``Cancer 
Survival in Developing Countries,'' International Agency for Research 
on Cancer, World Health Organization, Publication No. 145, 1998). We 
also have some information on annual bladder cancer mortality and 
incidence for the general population of Taiwan in 1996. The age-
adjusted annual incidence rates of bladder cancer for males and 
females, respectively, were 7.36 and 3.09 per 100,000, with 
corresponding annual mortality rates of 3.21 and 1.44 per 100,000 
(correspondence from Chen to Herman Gibb, January 3, 2000).
    Assuming that the proportion of males and females in the population 
is equal, these numbers imply that the mortality rate for bladder 
cancer in the general population of Taiwan, at present, is 45%. Since 
survival rates have most likely improved over the years since the 
original Taiwanese study, this number represents a lower bound on the 
survival rate for the original area under study (that is, one would not 
expect a higher rate of survival in that area at that time). This has 
implications for the bladder cancer risk estimates from the Taiwan 
data. For this estimate we have made the assumption that all bladder 
tumors in the study area in Taiwan were fatal. If there were any 
persons with bladder cancer who recovered and died from some other 
cause, then our estimate underestimated risk; that is, there were more 
cancer cases than cancer deaths. Based on the above discussion, we 
think bladder cancer incidence could be no more than 2 fold bladder 
cancer mortality; and that an 80% mortality rate would be plausible. In 
the benefits analysis we include estimates using an assumed mortality 
rate ranging from 80% to 100%.
    In the U.S. approximately one out of four individuals who is 
diagnosed with bladder cancer actually dies from bladder cancer. The 
mortality rate for the U.S. is taken from a cost of illness study 
recently completed by EPA (US EPA, 1999a). For those diagnosed with 
bladder cancer at the average age of diagnosis (70 years), the 
probability for dying of that disease during each year post-diagnosis 
were summed over a 20-year period to obtain the value of 26 percent. 
Mortality rates for U.S. bladder cancer patients have decreased overall 
by 24 percent from 1973 to 1996.
    In the NRC report, Table 10-11 shows excess risk estimates based on 
the Taiwanese male bladder cancer, using a Poisson regression model; a 
risk at the current MCL of 50 g/L is in the range of 1 to 
1.347 per 1,000. Table 10-12 presents excess lifetime risk estimates 
for bladder cancer in males calculated using EPA's 1996 proposed 
revisions to the cancer guidelines (US EPA 1996b). EPA selected four of 
these distributions as representative of the risks and uncertainty 
involved (selecting relatively high and relatively low estimates). 
These distributions (mean 1.049, 95% upper confidence limit 1.347; mean 
0.731, 95% upper confidence limit 0.807; mean 1.237, 95% upper 
confidence limit 1.548; and mean 1.129, 95% upper confidence limit 
1.229), were used in the EPA Monte Carlo simulations. All of these risk 
distributions are linear in the mean, and thus may be conservative 
assumptions, as the NRC report suggested the true relationship may be 
sublinear. If the true relationship is sublinear, i.e., lower than the 
straight line from 50 g/L to zero, the true risks at levels 
below 50 g/L are being overestimated. Other factors which 
might lower the true risk include the use of grouped data, the high 
Taiwanese dietary intake of arsenic, and the amount of selenium in the 
Taiwanese diet.
    NRC concluded that the present MCL in drinking water of 50 
g/L does not achieve EPA's goal for public health and requires 
downward revision. EPA did not request nor did NRC recommend a specific 
new MCL level.
6. Estimated Risk Reductions
    Estimated risk reductions for bladder cancer at various MCL levels 
were developed using Monte Carlo simulations. The inputs to the 
simulations were the distributions of relative risk factors (described 
in section X.A.4.), distributions of occurrence for arsenic levels at 3 
g/L and above, and bladder cancer risk distributions from the 
National Research Council report. The relative risk factor and 
occurrence distributions represent primarily population and occurrence 
variability, while the cancer risk distributions represent primarily 
uncertainty about the true risk. Thus the combined distributions 
reflect both variability and uncertainty. These combined distributions 
provide our best estimate of the actual risks faced by the exposed 
population, including the percentiles of the population facing various 
levels of risk.
    Estimated risk reductions for bladder cancer at various MCL levels 
are shown in Tables X-2a and X-2b. Table X-2a uses data on community 
water consumption from the new EPA study; Table X-2b uses data on total 
water consumption from the study. Populations at or above 10 
-\4\ risk levels are shown in Tables X-3a and X-3b.

[[Page 38943]]

The after treatment occurrence distributions were assumed to reflect 
treatment to 80% of the MCL level. The latter assumption is made since 
water systems tend to treat below the MCL level in order to provide a 
margin of safety.
    As shown in Table X-2a, bladder cancer risks at the 90th percentile 
of water intake, for the various MCL options under consideration, range 
from a multiple of 10-5 at 3 g/L (4-6  x  
10-5) to a multiple of 10-4 at 20 g/L 
(1.2-2.4  x  10-4). At 5 g/L , the 90th percentile 
level is 6-11  x  10-5; at 10 g/L the 90th 
percentile is 1.0-1.7  x  10-4. Table X-2b presents similar 
information. The risk estimates in Table X-2b are somewhat higher than 
those in Table X-2a because total water consumption is higher than 
community water consumption. Since there is uncertainty about these 
numbers, it is assumed that the range 1-1.5  x  10-4 
represents a risk level of essentially 10-4. It is then 
assumed that risks above 1.5  x  10-4 represent risks 
greater than 10-4. Table X-3a gives information about 
percentages of the exposed populations and the number of people exposed 
at 10-4 risk levels and above, and, using the stated 
definition for an over 10-4 risk level, above 
10-4. The numbers in this table show that at an MCL of 3 
g/L, only a small number (not quantifiable) face a risk level 
of greater than 10-4. At an MCL of 5 g/L, about 0.3 
to 0.8 million face such risk levels, at an MCL of 10 g/L, 0.8 
to 4 million, and at an MCL of 20 g/L, about 2.4 to 6.4 
million would be at such levels. Table X-3b gives similar information 
using total water consumption data. The mean bladder cancer risks for 
the exposed population at the various MCL options, after treatment, are 
shown in Tables X-4a and X-4b. These mean risks are used in the 
computation of the number of cases avoided, used later in the benefits 
evaluation section.

  Table X-2A.--Bladder Cancer Incidence Risks \1\ for High Percentile U.S. Populations Exposed at or Above MCL
                       Options, After Treatment \2\ (Community Water Consumption Data \3\)
----------------------------------------------------------------------------------------------------------------
              MCL (g/L)                        85th                  90th                  95th
----------------------------------------------------------------------------------------------------------------
3.............................................      3.2-5.4  x  10-5          4-6  x  10-5      4.3-7.5  x  10-5
5.............................................      5.3-9.3  x  10-5         6-11  x  10-5     7.5-13.0  x  10-5
10............................................     .88-1.49  x  10-4      1.0-1.7  x  10-4    1.26-2.12  x  10-4
20............................................     1.2-1.96  x  10-4     1.4--2.4  x  10-4     1.9-3.2  x  10-4
----------------------------------------------------------------------------------------------------------------
\1\ See Sections III.C. and D. for a description of other health effects, and Section X.B. for ``What-if?''
  estimates of magnitude for lung cancer risks.
\2\ The bladder cancer risks presented in this table provide our ``best'' estimates at this time. Actual risks
  could be lower, given the various uncertainties discussed, or higher, as these estimates assume a 100%
  mortality rate. An 80% mortality rate is used in the computation of upper bound benefits.
\3\ Discussed in Section X.A.2.


  Table X-2B.--Bladder Cancer Incidence Risks \1\ for High Percentile U.S. Populations Exposed at or Above MCL
                         Options, After Treatment \2\ (Total Water Consumption Data \3\)
----------------------------------------------------------------------------------------------------------------
              MCL (g/L)                        85th                  90th                  95th
----------------------------------------------------------------------------------------------------------------
3.............................................      3.8-6.4  x  10-5          4-7  x  10-5        5-8.7  x  10-5
5.............................................     6.3-10.5  x  10-5         7-12  x  10-5     8.5-14.5  x  10-5
10............................................     1.02-1.8  x  10-4      1.2-2.0  x  10-4  1.39-2.56  x  10-\4\
20............................................     1.4-2.34  x  10-4      1.7-2.8  x  10-4   2.17-3.56  x  10-4
----------------------------------------------------------------------------------------------------------------
\1\ See Sections III.C. and D. for a description of other health effects, and Section X.B. for ``What-if?''
  estimates of magnitude for lung cancer risks.
\2\ The bladder cancer risks presented in this table provide our ``best'' estimates at this time. Actual risks
  could be lower, given the various uncertainties discussed, or higher, as these estimates assume a 100%
  mortality rate. An 80% mortality rate is used in the computation of upper bound benefits.
\3\ Discussed in Section X.A.2.


    Table X-3A.--Percent of Exposed Population at 10-4 Risk or Higher for Bladder Cancer Incidence \1\ After
                              Treatment \2\ (Community Water Consumption Data \3\)
----------------------------------------------------------------------------------------------------------------
                                                                   Population at
                                                  Percent at 10-   10-4 risk or    Percent over     Population
               MCL (g/L)                    4 risk or        higher          10-4 *         over 10-4
                                                      higher        (millions)                      (millions)
----------------------------------------------------------------------------------------------------------------
3...............................................           1-2.6         0.3-0.7               1
5...............................................          1.5-12         0.4-3.2             1-3         0.3-0.8
10..............................................           11-34         2.9-9.1            3-15           0.8-4
20..............................................         19.5-41          5.2-11            9-24        2.4-6.4
----------------------------------------------------------------------------------------------------------------
\1\ See Sections III.C. and D. for a description of other health effects, and Section X.B. for ``What-if?''
  estimates of magnitude for lung cancer risks.
\2\ The percents presented in this table provide our ``best'' estimates at this time. Actual percents could be
  lower, given the various uncertainties discussed, or higher, as these estimates assume a 100% mortality rate.
  An 80% mortality rate is used in the computation of upper bound benefits.
\3\ Discussed in Section X.A.2.
* Where over 10-4 means 1.5  x  10-4 or above.
 Too low to calculate.


[[Page 38944]]


    Table X-3B.--Percent of Exposed Population at 10-4 Risk or Higher for Bladder Cancer Incidence \1\ After
                                Treatment \2\ (Total Water Consumption Data \3\)
----------------------------------------------------------------------------------------------------------------
                                                                   Population at
                                                  Percent at 10-   10-4 risk or    Percent over     Population
               MCL (g/L)                    4 risk or        higher          10-4 *         over 10-4
                                                      higher        (millions)                      (millions)
----------------------------------------------------------------------------------------------------------------
3...............................................             1-3         0.3-0.8               1
5...............................................            3-18         0.8-4.8             1-4         0.3-1.1
10..............................................           16-50        4.3-13.4            4-23         1.1-6.2
20..............................................           26-53          7-14.2           13-33        3.5-8.9
----------------------------------------------------------------------------------------------------------------
\1\ See Sections III.C. and D. for a description of other health effects, and Section X.B. for ``What-if?''
  estimates of magnitude for lung cancer risks.
\2\ The percents presented in this table provide our ``best'' estimates at this time. Actual percents could be
  lower, given the various uncertainties discussed, or higher, as these estimates assume a 100% mortality rate.
  An 80% mortality rate is used in the computation of upper bound benefits.
\3\ Discussed in Section X.A.2.
* Where over 10-4 means 1.5  x  10-4 or above.
 Too low to calculate.


 Table X-4A.--Mean Bladder Cancer Incidence Risks 1 for U.S. Populations
   Exposed at or Above MCL Options, After Treatment 2 (Community Water
                           Consumption Data 3)
------------------------------------------------------------------------
         MCL  (/L)              Mean exposed population risk
------------------------------------------------------------------------
3...................................  2.1-3.6  x  10-5
5...................................  3.6-6.1  x  10-5
10..................................  5.5-9.2  x  10-5
20..................................  6.9-11.6  x  10-5
------------------------------------------------------------------------
1 See Sections III.C. and D. for a description of other health effects,
  and Section X.B. for ``What-if?'' estimates of magnitude for lung
  cancer risks.
2 The bladder cancer risks presented in this table provide our ``best''
  estimates at this time. Actual risks could be lower, given the various
  uncertainties discussed, or higher, as these estimates assume a 100%
  mortality rate. An 80% mortality rate is used in the computation of
  upper bound benefits.
3 Discussed in Section X.A.2.


 Table X-4B.--Mean Bladder Cancer Incidence Risks 1 for U.S. Populations
     Exposed at or Above MCL Options, After Treatment 2 (Total Water
                           Consumption Data 3)
------------------------------------------------------------------------
         MCL  (/L)              Mean exposed population risk
------------------------------------------------------------------------
3...................................  2.6-4.5  x  10-5
5...................................  4.4-7.5  x  10-5
10..................................  6.7-11.4  x  10-5
20..................................  8.4-13.9  x  10-5
------------------------------------------------------------------------
1 See Sections III.C. and D. for a description of other health effects,
  and Section X.B. for ``What-if?'' estimates of magnitude for lung
  cancer risks.
2 The bladder cancer risks presented in this table provide our ``best''
  estimates at this time. Actual risks could be lower, given the various
  uncertainties discussed, or higher, as these estimates assume a 100%
  mortality rate. An 80% mortality rate is used in the computation of
  upper bound benefits.
3 Discussed in Section X.A.2.

B. ``What if?'' Scenario for Lung Cancer Risks

    The NRC report ``Arsenic in Drinking Water'' states that ``some 
studies have shown that excess lung cancer deaths attributed to arsenic 
are 2-5 fold greater than the excess bladder cancer deaths (NRC, 1999, 
pg. 8).'' Two-to-five fold greater would be 3.5 fold greater on 
average. Also in the U.S. the mortality rate from bladder cancer is 26% 
and the mortality rate of lung cancer is 88%. This suggests that if the 
risk of contracting lung cancer were identical to the risk of 
contracting bladder cancer, one would expect 3.4 times the number of 
deaths from lung cancer as from bladder cancer. Since these numbers are 
essentially the same, it seems reasonable to assume that the risk of 
contracting lung cancer is essentially the same as the rate of 
contracting bladder cancer,\1\ in the context of this ``what-if'' 
scenario. If the risk of contracting lung cancer from arsenic in 
drinking water is approximately equal to the risk of contracting 
bladder cancer, then the combined risk estimates of contracting either 
bladder or lung cancer would be approximately double the risk estimates 
presented in the previous tables.
---------------------------------------------------------------------------

    \1\ If ``X'' is the probability of contracting bladder cancer, 
then 0.26X is the probability of mortality from bladder cancer. If 
lung cancer deaths are 2 to 5 times as high as bladder cancer, then 
they are, on average, 3.5 times as high and the average probability 
of mortality from lung cancer would be 3.5 times 0.26X, or 0.91X. 
Since we also know that there is a 88% mortality rate from lung 
cancer, then if the probability of contracting lung cancer is ``Y,'' 
the probability of mortality from lung cancer can also be 
represented as 0.88Y. Setting the two ways of deriving the 
probability of mortality from lung cancer equal, or 0.91X = 0.88Y, 
one can solve for Y (Y= (0.91/0.88) X). Thus Y is approximately 
equal to X, and the rate of contracting lung cancer is approximately 
the same as the rate of contracting bladder cancer.
---------------------------------------------------------------------------

    EPA anticipates that a peer-reviewed quantification of lung cancer 
risk from arsenic exposure may be available between the time of 
proposal and promulgation. If so, EPA will make this information 
available for public comment through a Notice of Data Availability 
(NODA) and consider the analysis and public comment for the final 
rulemaking.

C. Evaluation of Benefits

    The evaluation stage in the analysis of risk reductions involves 
estimating the value of reducing the risks. Background information on 
the economic concepts that provide the foundation for benefits 
valuation, and the methods that are typically used by economists to 
monetize the value of risk reductions, such as wage-risk, cost of 
illness, and contingent valuation studies are provided in the RIA. The 
following sections describe the use of these techniques to estimate the 
value of the risk reductions attributable to the regulatory options for 
arsenic in drinking water. Described first is the approach for valuing 
the reductions in fatal risks; described next is the approach for 
valuing the reductions in nonfatal risks.
    The benefits calculated for this proposal are assumed to begin to 
accrue on the effective date of the rule and are based on a calculation 
referred to as the ``value of a statistical life'' (VSL), currently 
estimated at $5.8 million. The VSL is an average estimate derived from 
a set of 26 studies estimating what people are willing to pay to avoid 
the risk of premature mortality. Most of these studies examine 
willingness to pay in the context of voluntary acceptance of higher 
risks of immediate accidental death in the workplace in exchange for 
higher wages. This value is sensitive to differences in population 
characteristics and perception of risks being valued.
    For the present rulemaking analysis, which evaluates reduction in 
premature mortality due to carcinogen exposure, some have argued that 
the Agency

[[Page 38945]]

should consider an assumed time lag or latency period in these 
calculations. Latency refers to the difference between the time of 
initial exposure to environmental carcinogens and the onset of any 
resulting cancer. Use of such an approach might reduce significantly 
the present value estimate. EPA is interested in receiving comments on 
the extent to which the presentation of more detailed information on 
the timing of cancer risk reductions would be useful in evaluating the 
benefits of the proposed rule.
    Latency is one of a number of adjustments or factors that are 
related to an evaluation of potential benefits associated with this 
rule, how those benefits are calculated, and when those economic 
benefits occur. Other factors which may influence the estimate of 
economic benefits associated with avoided cancer fatalities include (1) 
a possible ``cancer premium'' (i.e., the additional value or sum that 
people may be willing to pay to avoid the experiences of dread, pain 
and suffering, and diminished quality of life associated with cancer-
related illness and ultimate fatality); (2) the willingness of people 
to pay more over time to avoid mortality risk as their income rises; 
(3) a possible premium for accepting involuntary risks as opposed to 
voluntary assumed risks; (4) the greater risk aversion of the general 
population compared to the workers in the wage-risk valuation studies; 
(5) ``altruism'' or the willingness of people to pay more to reduce 
risk in other sectors of the population; and (6) a consideration of 
health status and life years remaining at the time of premature 
mortality. Use of certain of these factors may significantly increase 
the present value estimate. EPA therefore believes that adjustments 
should be considered simultaneously. The Agency also believes that 
there is currently neither a clear consensus among economists about how 
to simultaneously analyze each of these adjustments nor is there 
adequate empirical data to support definitive quantitative estimates 
for all potentially significant adjustment factors. As a result, the 
primary estimates of economic benefits presented in the analysis of 
this proposed rule rely on the unadjusted estimate. However, EPA 
solicits comment on whether and how to conduct these potential 
adjustments to economic benefits estimates together with any rationale 
or supporting data commenters wish to offer. Because of the complexity 
of these issues, EPA will ask the Science Advisory Board (SAB) to 
conduct a review of these benefits transfer issues associated with 
economic valuation of adjustments in mortality risks. Consistent with 
the recommendations of the SAB, and subject to resolution of any 
technical problems, EPA will attempt to develop and present an estimate 
of the latency structure as a part of the analysis of the final rule, 
with prior solicitation of comment, if appropriate.
1. Fatal Risks and Value of a Statistical Life (VSL)
    To estimate the monetary value of reduced fatal risks (i.e., risks 
of premature death from cancer) predicted under different regulatory 
options, value of a statistical life (VSL) estimates are multiplied by 
the number of premature fatalities avoided. VSL does not refer to the 
value of an identifiable life, but instead to the value of small 
reductions in mortality risks in a population. A ``statistical'' life 
is thus the sum of small individual risk reductions across an entire 
exposed population.
    For example, if 100,000 people would each experience a reduction of 
1/100,000 in their risk of premature death as the result of a 
regulation, the regulation can be said to ``save'' one statistical life 
(i.e., 100,000  x  1/100,000). If each member of the population of 
100,000 were willing to pay $20 for the stated risk reduction, the 
corresponding value of a statistical life would be $2 million (i.e., 
$20  x  100,000). VSL estimates are appropriate only for valuing small 
changes in risk; they are not values for saving a particular 
individual's life.
    Of the many VSL studies, the Agency recommends using estimates from 
26 specific studies that have been peer reviewed and extensively 
reviewed within the Agency (US EPA, 1997f). These estimates, which are 
derived from wage-risk and contingent valuation studies, range from 
$0.7 million to $16.3 million and approximate a Wiebull distribution 
with a mean of $5.8 million (in 1997 dollars). To value the changes in 
fatal risks associated with the arsenic regulation, the mean estimate 
of $5.8 million is used.
    Use of these estimates to value the averted risks of premature 
death associated with the regulatory options for arsenic is an example 
of the benefit transfer technique, since the subject of most of the 
studies (i.e., job-related risks) differs from the fatal cancer risks 
averted by the regulatory options. Applying these studies results in 
several sources of potential bias (see latency discussion in section 
X.C.); however, quantitative adjustments to address these biases 
generally have not been developed or adequately tested and may be 
counterbalancing.\2\ EPA notes the uncertainties in the cost-benefit 
analyses, as required by section 1412(b)(3)(C)(i)(VII) of SDWA, and 
requests comment on alternate approaches.
---------------------------------------------------------------------------

    \2\ Some of the key sources of bias include the characteristics 
of the averted risks (whether they are voluntary or involuntary, 
ordinary or catastrophic, delayed or immediate, natural or man-made, 
etc.); the demographic characteristics of the group affected (e.g., 
age, income); the lag between exposure and diagnosis or incidence of 
the disease (latency) as well as between incidence and death; the 
baseline health status (i.e., whether a person is currently in good 
health) of affected individuals; and the presence of altruism (i.e., 
individual's willingness to pay to reduce risks incurred by others) 
(US EPA, 1997f).
---------------------------------------------------------------------------

2. Nonfatal Risks and Willingness To Pay (WTP)
    Estimates of the willingness to pay to avoid treatable, nonfatal 
cancers are the ideal economic measures used for evaluation of the 
reduction in nonfatal risks. However this information is not available 
for bladder cancer. Willingness to pay (WTP) data to avoid chronic 
bronchitis is available, however, and has been used before by EPA (the 
microbial/disinfection by-product (MDBP) rulemaking) as a surrogate to 
estimate the WTP to avoid non-fatal bladder cancer. The use of such WTP 
estimates is supported in the SDWA, as amended, at section 
1412(b)(3)(C)(iii): ``The Administrator may identify valid approaches 
for the measurement and valuation of benefits under this subparagraph, 
including approaches to identify consumer willingness to pay for 
reductions in health risks from drinking water contaminants.'' The WTP 
central tendency estimate of $536,000, to avoid chronic bronchitis, is 
used to monetize the benefits of avoiding non-fatal bladder cancers 
(Viscusi et al., 1991).
    EPA has also developed cost of illness estimates for bladder 
cancer, as reported in Table X-5. These estimates of direct medical 
costs are derived from a study conducted by Baker et al., (as cited in 
US EPA, 1997f) which uses data from a sample of Medicare records for 
1974-1981. These data include the total charges for inpatient hospital 
stays, skilled nursing facility stays, home health agency charges, 
physician services, and other outpatient and medical services. EPA 
combined these data with estimates of survival rates and treatment time 
periods to determine the average costs of initial treatment and 
maintenance care for patients who do not die of the disease.

[[Page 38946]]



       Table X-5.--Lifetime Avoided Medical Costs for Survivors (Preliminary Estimates, 1996 Dollars \1\)
----------------------------------------------------------------------------------------------------------------
                                    Date data      Number of cases     Estimated survival      Mean value per
          Type of cancer            collected          studied                rate            nonfatal case \2\
----------------------------------------------------------------------------------------------------------------
Bladder..........................    1974-1981  5% of 1974 Medicare   26 percent (after 20  $179,000 (for
                                                 patients (sample      years).               typical individual
                                                 from national                               diagnosed at age
                                                 statistics).                                70)
----------------------------------------------------------------------------------------------------------------
\1\ These costs increase by 2.8 percent when inflated to 1997 dollars, based on the consumer price index for the
  costs of medical commodities and services.
\2\ Undiscounted costs.
Source: US EPA, 1999a.

D. Estimates of Quantifiable Benefits of Arsenic Reduction

    Benefits estimates for avoided cases of bladder cancer were 
calculated using mean population risk estimates at various MCL levels. 
Table X-6 gives the mean populations risk estimates used, which are a 
composite of the mean population risk estimates discussed earlier. 
Lifetime risk estimates were converted to annual risk factors, and 
applied to the exposed population to determine the number of cases 
avoided. These cases were divided into fatalities and non-fatal cases 
avoided, based on survival information. The avoided premature 
fatalities were valued based on the VSL estimates discussed earlier, as 
recommended by EPA current guidance for cost/benefit analysis. The 
avoided non-fatal cases were valued based on the willingness to pay 
estimates for the avoidance of chronic bronchitis. The upper bound 
estimates have been adjusted upwards to reflect an 80% mortality rate, 
which is a plausible mortality rate for the area of Taiwan during the 
Chen study.
    The ``What if?'' scenario for lung cancer benefits (described in 
section X.B.) was used to estimate potential benefits for avoided cases 
of lung cancer. This scenario is based on the statement in the NRC 
report ``Arsenic in Drinking Water'' that ``some studies have shown 
that excess lung cancer deaths attributed to arsenic are 2-5 fold 
greater than the excess bladder cancer deaths (NRC, 1999, pg. 8).'' It 
was shown in section X.D that the statement implies (if it were 
accurate for the U.S.), that, because of the relative U.S. mortality 
rates for bladder and lung cancer, the rate of contracting lung cancer 
could be essentially the same as the rate of contracting bladder 
cancer. This would double the number of cancer cases avoided, for both 
low and high estimates. The potential monetized benefits for lung 
cancer would be several times higher than those for bladder cancer, due 
to the higher number of fatalities involved with lung cancer.
    Another way of considering the addition of lung cancer effects 
would be to estimate the potential benefits from avoided cases of lung 
cancer using the 2-5 times range for fatalities (that is, taking the 
expected number of bladder cancer fatalities and multiplying them by 2 
and then 5 to obtain a range of lung cancer fatalities, and then 
factoring in non-fatal cases).
    Benefits (and costs) are assumed to accrue on the effective date of 
the rule. Table X-7 displays the results.

 Table X-6.-Mean Bladder Cancer Incidence Risks \1\ for U.S. Populations
   Exposed at or Above MCL Options, After Treatment \2\ (Composite of
                          Tables X-5a and X-5b)
------------------------------------------------------------------------
                                                        Mean exposed
                MCL (g/L)                     population risk
------------------------------------------------------------------------
3.................................................       2.1-4.5 x 10- 5
5.................................................       3.6-7.5 x 10- 5
10................................................      5.5-11.4 x 10- 5
20................................................     6.9-13.9 x 10- 5
------------------------------------------------------------------------
\1\ See Sections III.C. and D. for a description of other health
  effects, and Section X.B. for ``What-if?'' estimates of magnitude for
  cancer risks.
\2\ The bladder cancer risks presented in this table provide our
  ``best'' estimates at this time. Actual risks could be lower, given
  the various uncertainties discussed, or higher, as these estimates
  assume a 100% mortality rate. An 80% mortality rate is used in the
  computation of upper bound benefits.


                                    Table X-7.--Estimated Costs and Benefits From Reducing Arsenic in Drinking Water
                                                                    [Millions, 1999]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                     ``What if'' scenario \4\ and potential non-quantified benefits
                                                                              --------------------------------------------------------------------------
                               Total national  Total national   Total bladder    ``What If''
 Arsenic level (g/l)   costs to CWSs   costs to CWSs   cancer health    lung cancer
                                     \1\         and NTNCWSs    benefits \3\       health              Potential non-quantifiable health benefits
                                                     \2\                          benefits
                                                                                  estimates
--------------------------------------------------------------------------------------------------------------------------------------------------------
3............................      $643.1-753    $644.6-756.3     $43.6-104.2       $47.2-448   Skin Cancer.
                                                                      \5\(79)      \6\(213.4)   Kidney Cancer.
                                                                                                Cancer of the Nasal Passages.
5............................     377.3-441.8     378.9-444.9       31.7-89.9          35-384   Liver Cancer.
                                                                    \5\(64.3)      \6\(173.4)   Prostate Cancer.
10...........................     163.3-191.8     164.9-194.8       17.9-52.1        19.6-224   Cardiovascular Effects.
                                                                      \5\(37)        \6\(100)   Pulmonary Effects.
                                                                                                Immunological Effects.
                                                                                                Neurological Effects.

[[Page 38947]]

 
20...........................       61.6-72.9       63.2-77.1        7.9-29.8         8.8-128   Endocrine Effects.
                                                                    \5\(19.8)       \6\(53.4)   Reproductive and Developmental Effects.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Costs include treatment, monitoring, O&M, and administrative costs to CWSs and State costs for administration of water programs. The lower number
  shows costs annualized at a consumption rate of interest of 3%, EPA's preferred approach. The higher number shows costs annualized at 7%, which
  represents the standard discount rate preferred by OMB for benefit-cost analyses of government programs and regulations.
\2\ Costs include treatment, monitoring, O&M, administrative costs to CWSs; monitoring and administrative costs to NTNCWSs; and State costs for
  administration of water programs.
\3\ The upper bound estimate includes an adjustment to account for a possible mortality risk of 80%. It is possible that this risk could have been below
  80%, which would lead to increased benefits. The actual risk depends on the survival rate for bladder cancer in the area of Taiwan studied by Chen,
  which is unknown.
\4\ These estimates are based on the ``what if'' scenario for lung cancer, where the risks of a fatal lung cancer case associated with arsenic are
  assumed to be 2-5 times that of a fatal bladder cancer case.
\5\The number in parentheses indicates the bladder cancer health benefits assuming an 80% mortality rate for bladder cancer in the area of the Chen
  study, and starting from the midpoint of the benefits range when mortality and incidence are assumed equivalent.
\6\The number in parentheses is the midpoint of the range and corresponds to an assumption that the risk of fatal lung cancer is 3.5 times the risk of
  fatal bladder cancer.

F. NDWAC Working Group (NDWAC, 1998) on Benefits

    The National Drinking Water Advisory Council (NDWAC) recommends 
that:
    (1) EPA should focus its benefits analysis efforts primarily on 
assessing effects on human health, defining these effects as clearly as 
possible and using the best available data to value them. It is also 
recommended that EPA should also consider, where appropriate, taste and 
odor improvements, reduction of damage to water system materials, 
commercial water treatment cost reductions, benefits due to source 
water protection (e.g., ecological benefits and non-use benefits), and 
benefits derived from the provision of information on drinking water 
quality (e.g., a household's improved ability to make informed 
decisions concerning the need to test or filter tap water);
    (2) EPA should devote substantial efforts to better understanding 
the health effects of drinking water contaminants, including the types 
of effects, their severity, and affected sensitive subpopulations. 
Better information is also needed on exposures and the effects of 
different exposure levels, particularly for contaminants with threshold 
effects. These efforts should pay particular attention to obtaining 
improved information concerning impacts on children and other sensitive 
populations;
    (3) EPA should clearly identify and describe the uncertainties in 
the benefits analysis, including descriptions of factors that may lead 
the analysis to significantly understate or overstate total benefits. 
Factors that may have significant but indeterminate effects on the 
benefits estimates should also be described;
    (4) EPA should consider both quantified and non-quantified benefits 
in regulatory decision-making. The information about quantified and 
non-quantified (qualitative) benefits should be presented together in a 
format, such as a table, to ensure that decision-makers consider both 
kinds of information;
    (5) EPA should consider incremental benefits and costs, total 
benefits and costs, the distribution of benefits and costs, and cost-
effectiveness in regulatory decision-making. This information should be 
presented together in a format, such as a table, to ensure its 
consideration by decision-makers;
    (6) Whenever EPA considers regulation of a drinking water 
contaminant, it should evaluate and consider, along with water 
treatment requirements to remove a contaminant, source water protection 
options to prevent such a contaminant from occurring. The full range of 
benefits of those options should be considered.

XI. Risk Management Decisions: MCL and NTNCWSs

A. What Is the Proposed MCL?

    EPA is proposing an arsenic MCL of 5 g/L and soliciting 
comments on options of 3g/L, 10 g/L, and 20 
g/L. EPA is also asking that commenters provide their 
rationale and any supporting data or information for the option they 
prefer.
    The SDWA generally requires that EPA set the MCL for each 
contaminant as close as feasible to the MCLG, based on available 
technology and taking costs to large systems into account. The 1996 
amendments to the SDWA added the requirement that the Administrator 
determine whether or not the quantifiable and nonquantifiable benefits 
of an MCL justify the quantifiable and nonquantifiable costs based on 
the Health Risk Reduction and Cost Analysis (HRRCA) required under 
section 1412(b)(3)(C). The 1996 SDWA amendments also provided new 
discretionary authority for the Administrator to set an MCL less 
stringent than the feasible level if the benefits of an MCL set at the 
feasible level would not justify the costs (section 1412(b)(6)). This 
proposal to establish an MCL for arsenic of 5 g/L is the first 
time EPA has invoked this new authority.
    In conducting this analysis, EPA considered all available 
scientific information concerning the health effects of arsenic, 
including various uncertainties in the interpretation of the results. 
As discussed in more detail below, an array of health endpoints of 
concern were considered in this analysis. For some of these, the risk 
can currently be quantified (i.e., expressed in numerical terms); and 
for some, it cannot. Similarly, there are a variety of health and other 
benefits attributable to reductions in levels of arsenic in drinking 
water, some of which can be monetized (i.e., expressed in monetary 
terms) and others that cannot yet be monetized. All were considered in 
this analysis. The array of factors taken into account in making risk 
management decisions for arsenic underscore the difficulty of 
recommending the most appropriate regulatory level. A detailed

[[Page 38948]]

discussion of each of the principal factors considered follows.
1. Feasible MCL
    Because arsenic is a carcinogen with no established mode of action, 
EPA is proposing that the MCLG be set at zero. To establish the MCL, 
EPA must first determine the level which is as close to this level as 
feasible. EPA has determined that 3 g/L is technologically 
feasible for large systems based on peer-reviewed treatment information 
and the practical quantitation level achievable with available 
analytical methods.
2. Principal Considerations in Analysis of MCL Options
    In addition to the feasible MCL of 3 g/L, the Agency 
evaluated MCL options of 5 g/L, 10 g/L, and 20 
g/L. EPA considered the health effects associated with 
arsenic, the risk levels to the population for these health effects 
that would remain after implementation, and the costs and benefits of 
the different options (both those that could be monetized and/or 
quantified now and those that could not). The Agency's assessment 
centered on the health risk posed by arsenic in drinking water as well 
as on the benefits and costs imposed by the options evaluated. These 
options were then analyzed, taking into consideration the uncertainties 
involved in each of these factors. EPA solicits public comment on all 
the factors it considered in making this decision.
    Estimates of risk levels to the population remaining after the 
regulation is in place provide a perspective on the level of public 
health protection and benefits. The SDWA clearly places a particular 
focus on public health protection afforded by MCLs. For instance, where 
EPA decides to use its discretionary authority after a determination 
that the benefits of an MCL would not justify the costs, section 
1412(b)(6)(A) requires EPA to set the MCL at a level that ``maximizes 
health risk reduction benefits at a cost that is justified by the 
benefits.''
    The SDWA requires the Agency to consider both quantifiable and 
nonquantifiable health risk reduction benefits (quantifiable benefits 
can include both those that are monetizable and those that are not). 
Non-monetizable benefits range from those about which some quantitative 
information is known (such as skin cancer), and those which are more 
qualitative in nature (such as some of the non-cancer health effects 
associated with arsenic). If additional potential benefits that are 
presently not monetized (see Table XI-1) could be estimated at some 
future point, the benefits might increase further. (Important 
assumptions inherent in EPA's benefits estimates, including the value 
of a statistical life and willingness to pay are discussed in section 
X.C.)
    EPA considered the relationship of the monetized benefits to the 
monetized costs for each option. While equality of monetized benefits 
and costs is not a requirement under section 1412(b)(6)(A), this 
relationship is still a useful tool in comparing costs and benefits. 
However, EPA believes that reliance on a simple arithmetic analysis of 
whether monetized benefits outweigh monetized costs is inconsistent 
with the HRRCA's instruction to consider both quantifiable and non-
quantifiable costs and benefits. The Agency therefore believes it is 
necessary to also examine the qualitative and non-monetized benefits 
and consider these benefits in establishing the MCL.
3. Findings of NRC and Consideration of Risk Levels
    The Agency based its evaluation of the risk posed by arsenic at the 
MCL options of 3 g/L, 5 g/L, 10 g/L and 20 
g/L on national and international research, the bladder cancer 
risk analysis provided by the National Research Council (NRC) report 
issued by the National Academy of Sciences (NRC 1999), and the NRC's 
qualitative statements of overall risk of combined cancers. The Agency 
is relying heavily on the findings of the NRC for a number of reasons. 
In carrying out its charge, the NRC assembled an independent body of 
preeminent scientists from several disciplines. This committee examined 
and carefully analyzed more information than has been available before, 
and NRC had the draft report peer reviewed by thirteen other 
individuals with ``diverse perspectives and technical expertise (NRC 
1999b).'' EPA decided, in 1996, to charge the NRC with evaluating EPA's 
two risk assessments for arsenic and considering the most current 
national and international research on arsenic. The NRC determined that 
the current MCL of 50 g/L is not adequately protective and 
should be revised downward as soon as possible. The NRC conducted a 
number of statistical analyses in making this determination. The report 
also recommended that EPA conduct separate analyses for ``bladder, 
lung, and other internal cancers,'' as well as consider the combined 
impact of these various health effects.
    Given the release date of the NRC report (March 1999) relative to 
the timing of the proposed rule and the additional analyses needed to 
definitively quantify all endpoints of concern, EPA chose to use NRC's 
bladder cancer analysis to quantify and monetize the bladder cancer 
risk for the proposed rule. NRC provided quantitative risk factors for 
bladder cancer, that, when combined with key risk characterization 
scenarios by EPA and qualitative benefits, yield risks and benefits 
associated with various possible MCL options. The NRC report also noted 
that lung cancer deaths due to arsenic could be 2 to 5 times higher 
than bladder cancer deaths, considering the frequency and incidence of 
cancers projected from international studies. However, the report did 
not provide a numeric risk-based quantification analysis for this 
judgment similar to that provided for bladder cancer. As noted in 
section X.E., EPA approximated the potential benefits of avoiding 
arsenic-related lung cancer by assuming that the probability of 
incidence of lung cancer is approximately equal to that of bladder 
cancer. One can then use the death rate associated with lung cancer 
(88% for lung cancer as compared to 26% for bladder cancer) to derive 
benefits and to consider the implications of this health endpoint on 
risk. The risk factors associated with various MCL options increase 
under this ``What If'' analysis, with 10 g/L being on the 
upper end or just outside of the Agency's 1  x  10-4 risk 
range and more stringent MCL options being more solidly under this risk 
ceiling.
    EPA anticipates that a peer reviewed quantification of lung cancer 
risk from arsenic exposure may be available between the time of 
proposal and promulgation. If so, EPA will make this information 
available for public comment through a Notice of Data Availability 
(NODA) and consider the analysis and public comment for the final 
rulemaking.
    Individual risk varies widely depending on susceptibility, amount 
of drinking water consumption, dietary levels of arsenic, years of 
exposure, and other factors. Consequently, any single MCL does not 
provide the same level of protection to all individuals. While not 
required by statute, the Agency has historically set protectiveness 
levels within a risk range of 10-\4\ to 10-\6\. 
EPA has sought to ensure that drinking water standards were established 
at levels such that less than 10% of the exposed population faced a 
risk that exceeded the chosen risk level. This conclusion is based on a 
recognition of its responsibility to protect public health, together 
with its obligation to consider a range of risk management factors when 
establishing regulatory levels.

[[Page 38949]]

4. Non-Monetized Health Effects
    There are a number of important non-monetized benefits that EPA 
considered in its analysis. Chief among these are certain health 
impacts known to be caused by arsenic (such as skin cancer).
    A number of epidemiologic studies conducted in several countries 
(e.g., Taiwan, Japan, England, Hungary, Mexico, Chile, and Argentina) 
report an association between arsenic in drinking water and skin cancer 
in exposed populations. Studies conducted in the U.S. have not 
demonstrated an association between inorganic arsenic in drinking water 
and skin cancer. However, these studies may not have included enough 
people in their design to detect these types of effects.
    There were also a large number of other health effects associated 
with arsenic, discussed in section III, and listed in Table XI.1, which 
are not monetized, due to lack of appropriate quantitative data. These 
health effects include other cancers such as prostate cancer and 
cardiovascular, pulmonary, neurological and other non-cancer endpoints.
    Other benefits not monetized for this proposal include customer 
peace of mind from knowing drinking water has been treated for arsenic 
and reduced treatment costs for currently unregulated contaminants that 
may be co-treated with arsenic. To the extent that reverse osmosis is 
used for arsenic removal, these benefits could be substantial. Reverse 
osmosis is the primary point of use treatment, and it is expected that 
very small systems will use this treatment to a significant extent.
5. Sources of Uncertainty
    Among the non-quantifiable factors EPA considered in choosing the 
proposed MCL was Congress' intent that EPA ``reduce * * * [scientific] 
uncertainty'' in promulgating the arsenic regulation, reflected in the 
1412(b)(12) arsenic research plan provisions and the legislative 
history for the arsenic provision (S. Rep. 104-169, 104th Cong., 1st 
Sess. at 39-40).
    All assessments of risk are characterized by an amount of 
uncertainty. Some of this can be reduced by collecting more data or 
data of a different sort; for other types of uncertainty, improved data 
or assessment methods can allow one to define the degree to which an 
estimate is likely to be above or below the ``true'' risk. For the 
arsenic risk assessment, there are some definable sources of 
uncertainty. These include (but aren't limited to) the following: 
choice of endpoint and population; uncertainty about the exact exposure 
of individuals in the study population; issues on applying data from 
rural Taiwanese to the heterogenous population of the U.S.; the 
inability to know precisely how a chemical causes cancer in humans (the 
mode of action, which affects judgments as to the shape of the 
chemical's dose response curve at low doses); choice of mathematical 
modeling procedures. Congress established a dual path for arsenic in 
SDWA: on the one hand, EPA is to issue a proposed MCL in 4\1/2\ years; 
on a parallel track EPA is to develop a long-term research plan, 
complete the required consultations and peer reviews, complete the 
research, and fully consider the research results. While the plan has 
been developed and research is underway, not all research results will 
be available for the final rule. However, EPA did obtain through the 
NRC study the most authoritative review of existing scientific 
information available. This review examined the areas of uncertainty 
listed above.
    EPA considered uncertainty about arsenic's mode of action and the 
shape of the dose response curve below the observable range of data. 
EPA is proposing an MCLG of zero. This decision is supported by the 
NRC's findings that the dose-response relationship at low doses is 
uncertain and that a conservative, default assumption of linearity is 
advisable. (An assumption of linearity in the dose-response 
relationship implies that there is no ``safe'' level that can be 
identified at which no health effects are expected to occur.) However, 
the Agency also notes the NRC's conclusion that ``* * * a sublinear 
dose-response curve in the low dose range is predicted, although 
linearity cannot be ruled out.'' (NRC, 1999, pg. 6). EPA believes the 
NRC study's articulation of uncertainty about the shape of the dose-
response curve below the observed health effect range is an important 
qualitative consideration and, given Congress' concern about scientific 
``uncertainty'' in setting the arsenic level, guides EPA to a default 
assumption of linearity.
    The choice of one endpoint for risk assessment is a judgment call. 
While this choice is guided by the best available science, it 
introduces uncertainty. Basing the risk assessment on incidence of 
bladder tumors will underestimate the combined risk of all arsenic-
induced health effects. Section XI.A.4. discusses how assessments of 
other tumor types and health endpoints would result in a higher 
estimate of arsenic risk.
    Another source of uncertainty is in the application of data from 
one human population to another. EPA believes that the differences in 
dietary contributions of arsenic that NRC identified in the Taiwan 
study population and the U.S. are important to consider and a source of 
uncertainty in interpreting the results. NRC estimated that daily 
inorganic arsenic intake from food in the U.S. ranges from 1.3 
g/day for infants, to 4.5 g/day for males 14-16 years 
old and 5.2 g/day for females 14-16 years old, to a maximum of 
12.5 g/day for 60-65 year-old males and 9.7 g/day for 
60-65 year old females. On the other hand, NRC cited a study (Schoof et 
al., 1998) that estimated the Taiwanese obtain 31 g/day of 
inorganic arsenic from yams and 19 g/day from rice, ``for a 
total of 50 g/day within a range of estimates of 15-211 
g/day (NRC, 1999, pg. 51).'' NRC noted (p. 24) that ``Limited 
data on dietary arsenic intake in the blackfoot-disease region now 
available suggest that arsenic intake from food is higher in Taiwan 
than in the United States.'' NRC noted that EPA previously observed 
that arsenic intake from sources other than drinking water would 
overestimate the unit risk calculated from the Taiwan study (US EPA 
1988, pg. 86). The report noted that improved quantification of arsenic 
in Taiwanese food might affect the risk assessment for arsenic in 
drinking water in the U.S. (NRC 1999, pg. 6).
    In addition, the NRC report discussed laboratory animal studies 
that indicated that selenium reduced the toxicity of arsenic. While 
there is no direct evidence for humans, NRC noted that ``Selenium 
status there [in Taiwan] should be considered a moderator of arsenic 
toxicity and taken into account when the Taiwanese data are applied to 
populations with adequate selenium intakes (NRC, 1999, pg. 240).'' The 
NRC report cited studies comparing urinary selenium concentrations and 
blood serum selenium concentrations; these were lower for the Taiwanese 
by comparison to other study populations including people in the U.S.
    NRC noted that the ``model choice can have a major impact on 
estimated low-dose risks when the analysis is based on epidemiological 
data (NRC 1999, pg. 294).'' NRC noted that EPA's 1988 risk assessment 
used the multistage Weibull model to estimate a lifetime skin cancer 
risk of 1  x  10-\3\ for U.S. males exposed to arsenic at 50 
g/L. In their report NRC discussed the implications (both in a 
general sense and specifically for the Tseng data) of using data from 
an ecological study, and of using grouped data. They also reported the 
results of applying both a multistage Weibull and a Poisson model. When 
they re-assorted data into varying exposure groups, there

[[Page 38950]]

was a strong effect on the fitted Weibull model. NRC concluded: ``Thus 
the fact that grouping does have a strong effect provides evidence of 
additional measurement error in the arsenic concentrations being 
assigned at the village level (NRC, 1999, pg. 284).'' NRC used median 
village arsenic concentrations to represent exposure levels. The Expert 
Panel (US EPA, 1997d) noted that biases from using average doses for 
groups leads to overestimation of risk.

    ``* * * [D]espite a distribution of doses in the population, 
those individuals exhibiting effects would tend also to be those who 
received the highest doses; because of this, deriving an average 
dose based on affected individuals would to some extent bias risk 
estimates upward. Similarly attribution of the total excess risk in 
the population to arsenic exposure alone could also be expected to 
inflate the estimate of risk if the population is also characterized 
by other risk factors such as smoking, excess exposure to sunlight, 
nutritional status, and so on (US EPA, 1997d, pg. 31).''

    The Poisson model with a quadratic term for age and a linear 
term for exposure fit as well as the multistage Weibull model, and 
had less variability in risks from regrouping the exposure 
intervals. Results from the NRC Poisson model estimations were used 
in the EPA analysis of bladder cancer risks.
    NRC noted that ``Ecological studies in Chile and Argentina have 
observed risks of lung and bladder cancer of the same magnitude as 
those reported in the studies in Taiwan at comparable levels of 
exposure.'' This observation increases confidence in the risk 
estimates based on the Tseng data. That these populations are 
different in terms of ethnic background, dietary patterns, and 
potential for other exposures also decreases the level of concern 
about generalized applicability of the Taiwanese data for risk 
assessment.
    EPA considered these various uncertainties associated with 
interpretation of the health effects of arsenic in making risk 
management decisions and in selecting an appropriate regulatory 
level. The Agency requests comment on whether we have properly 
weighed the uncertainties which overestimate and underestimate risk 
of the proposed MCL.
    There is also a measure of uncertainty about the costs 
associated with various possible regulatory levels. EPA has provided 
its best estimates of the costs, but recognizes that a number of 
stakeholders have performed independent analyses suggesting that the 
costs may be higher than those estimated by EPA. EPA requests 
comment on its cost estimates and any additional information 
commenters may have on possible costs of the rule.

6. Comparison of Benefits and Costs

    The monetized costs and monetized benefits of the proposed rule, 
and the methodologies used to calculate them, are discussed in 
detail in sections IX, X, and XIII of this preamble and in the 
HRRCA. Overall estimates of monetized costs and monetized benefits 
associated with various MCL options are provided in Table XI-1. 
There are also many health effects which have not been monetized, as 
is also shown in Table XI-1.

                                    Table XI-1.--Estimated Costs and Benefits From Reducing Arsenic in Drinking Water
                                                                  [In 1999 $ millions]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                     ``What if'' scenario \4\ and potential non-quantified benefits
                                                                              --------------------------------------------------------------------------
                               Total national  Total national   Total bladder    ``What if''
Arsenic level  (g/L)   costs to CWSs   costs to CWSs   cancer health    lung cancer
                                     \1\         and NTNCWSs    benefits \3\       health              Potential non-quantifiable health benefits
                                                     \2\                          benefits
                                                                                  estimates
--------------------------------------------------------------------------------------------------------------------------------------------------------
3............................       643.1-753     644.6-756.3      43.6-104.2        47.2-448   Skin Cancer.
                                                                     \5\ (79)     \6\ (213.4)   Kidney Cancer.
                                                                                                Cancer of the Nasal Passages.
5............................     377.3-441.8     378.9-444.9       31.7-89.9          35-384   Liver Cancer.
                                                                   \5\ (64.3)     \6\ (173.4)   Prostate Cancer.
                                                                                                Cardiovascular Effects.
10...........................     163.3-191.8     164.9-194.8       17.9-52.1        19.6-224   Pulmonary Effects.
                                                                     \5\ (37)       \6\ (100)   Immunological Effects.
                                                                                                Neurological Effects.
20...........................       61.6-72.9       63.2-77.1        7.9-29.8         8.8-128   Endocrine Effects.
                                                                   \5\ (19.8)      \6\ (53.4)   Reproductive and Developmental Effects.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Costs include treatment, monitoring, O&M, and administrative costs to CWSs and State costs for administration of water programs. The lower number
  shows costs annualized at a consumption rate of interest of 3%, EPA's preferred approach. The higher number shows costs annualized at 7%, which
  represents the standard discount rate preferred by OMB for benefit-cost analyses of government programs and regulations.
\2\ Costs include treatment, monitoring, O&M, administrative costs to CWSs; monitoring and administrative costs to NTNCWSs; and State costs for
  administration of water programs.
\3\ The upper bound estimate includes an adjustment to account for a possible mortality risk of 80%. It is possible that this risk could have been below
  80%, which would lead to increased benefits. The actual risk depends on the survival rate for bladder cancer in the area of Taiwan studied by Chen,
  which is unknown.
\4\ These estimates are based on the ``what if'' scenario for lung cancer, where the risks of a fatal lung cancer case associated with arsenic are
  assumed to be 2-5 times that of a fatal bladder cancer case.
\5\ The number in parentheses indicates the bladder cancer health benefits assuming an 80% mortality rate for bladder cancer in the area of the Chen
  study, and starting from the midpoint of the benefits range when mortality and incidence are assumed equivalent.
\6\ The number in parentheses is the midpoint of the range and corresponds to an assumption that the risk of fatal lung cancer is 3.5 times the risk of
  fatal bladder cancer.

7. Conclusion and Request for Comment
    In summary, based on the NRC report, EPA agrees that the current 
MCL of 50 g/L is too high and must be made more protective of 
human health. Because EPA is proposing an MCLG for arsenic of 0, the 
MCL must be set as close as feasible to the MCLG, unless EPA invokes 
its discretionary authority to set a different MCL at a level where the 
costs are justified by the benefits. EPA believes that the feasible 
level for arsenic is 3 g/L. Today, EPA is proposing that the 
arsenic MCL be set at 5 g/L.
    EPA believes that setting the MCL at 3 g/L, the feasible 
level in this case, may not be justified at this time, given the 
uncertainty regarding the relationship between the monetized benefits 
and the monetized costs at that level, the current uncertainty of the 
non-monetized benefits, and the degree of scientific uncertainty 
regarding the dose-response curve for an MCL at that level (affected by 
differences in nutrition and arsenic from food). Because there is a 
substantial possible imbalance between currently estimated monetized 
costs and benefits at the

[[Page 38951]]

feasible level of 3 g/L, and a lack of certainty concerning 
the non-monetized costs and potential non-monetized benefits, EPA is 
proposing a standard other than the feasible level, using its 
discretionary authority in section 1412(b)(6). (See Senate Rep. 104-
169, 104th Cong., 1st Sess. at 33). The statute requires that a level 
proposed or promulgated using this discretionary authority be one which 
maximizes health risk reduction at a level where the costs are 
justified by the benefits. EPA believes that the 5 g/L MCL 
best meets this statutory test. EPA solicits comment on this finding, 
as described in more detail below.
    As discussed earlier in section XI.A.4., EPA believes that there 
are a number of not yet quantified adverse health effects that pose a 
significant risk to public health. While the relationship of actual 
monetized benefits to monetized costs at 5 g/L, $31.7-$89.9 
million for bladder cancer benefits (plus possible lung cancer benefits 
of $35-$384 million based on the ``What If'' scenario) vs. $378.9-444.9 
million in costs, is uncertain. EPA believes the range of benefits 
supports that level, especially when there may potentially be 
substantial non-monetized benefits factored into the analysis. EPA 
believes that, given the guidance of the NRC report, these potential 
non-monetized benefits, including a number of non-cancer health effects 
(see Table XI-1), are substantial enough to strike a reasonable balance 
between benefits and costs. Strict parity of monetized costs and 
monetized benefits is not required to find that the benefits of a 
particular MCL option are justified under the statutory provisions of 
Sec. 1412(b)(6). In addition, at 5 g/L, the remaining risks 
(of bladder cancer) to the exposed population after the rule's 
implementation are well within the 10-4 range, which is 
protective of public health. As a result, EPA finds that the actual 
risk levels (including risks of potential non-monetized health effects) 
at 5 g/L are high enough to justify this MCL, and it is 
therefore the level which maximizes health protection at a level where 
the costs are justified.
    As discussed earlier, EPA has, as a matter of policy typically 
established MCLs for cancer-causing contaminants to ensure that the 
risks of excess cancer deaths represented by exposure to drinking water 
at the MCL over the course of a lifetime are within a range of one in 
10,000 to one in 1,000,000. EPA believes that this range is reasonably 
protective of public health consistent with the goals of the Safe 
Drinking Water Act. In using its statutory discretion under section 
1412(b)(6)(A) to set a standard less stringent than the feasible level 
that maximizes health risk reduction at a cost that is justified by the 
benefits, EPA is proposing that it should choose a level that falls 
within the afore-mentioned target risk range. EPA is proposing to stay 
within this risk range even if the monetized benefits of a standard set 
at the upper end of the range are below the costs, as may be the case 
with this rule. EPA believes that important factors in this evaluation 
are the considerable non-quantifiable benefits that may be attributable 
to the proposed MCL. EPA also notes, as discussed earlier, that 
Congress did not direct EPA to ensure strict equality of monetizable 
costs and benefits in applying its discretionary authorities under 
section 1412(b)(6)(A). EPA requests comments on its proposed use of the 
new authority under section 1412(b)(6)(A) of the SDWA.
    The risk assessment for bladder cancer indicates that a standard 
set at 10 g/L would fall at the upper end of the target risk 
range, with 5 g/L more solidly within that risk range. 
However, there are two important sets of considerations when using 
available health effects information and studies to help determine the 
appropriate level for a proposed new standard. On the one hand, 
multiple health endpoints are of concern in ensuring that the standard 
is adequately protective. As noted earlier, the NRC expresses concern 
about lung cancer and other health endpoints and indicated that excess 
lung cancer deaths from arsenic in drinking water could be 2-5 times 
the level of bladder cancer deaths. If these other risks were fully 
quantified, the total risk at 10 g/L might be well above 1  x  
10-4 (the upper end of the risk range), given that the 
quantified risk of bladder cancer alone appears to be at approximately 
this level.
    On the other hand, there is uncertainty in the quantification of 
bladder cancer risk (as well as other health endpoints) and this risk 
estimate includes a number of conservative assumptions, as discussed 
previously. These include the assumptions of using a linear dose-
response function; the fact that the dose-response data from the Taiwan 
epidemiologic study are based upon grouped occurrence information from 
wells used by the study population; and the possibility that the study 
population was more susceptible to arsenic in drinking water (as 
compared to the U.S. population) due to the relatively high dietary 
intake and dietary deficiencies in other elements (e.g., selenium) that 
might mitigate the results of arsenic. Thus, the risk of bladder cancer 
alone might be well below current estimates which represent EPA's best 
estimate at this time using currently available data and standard 
methodologies. The proposed MCL attempts to balance these 
countervailing considerations in establishing a level that is 
protective of public health.
    Given these competing sources of uncertainty, EPA believes it is 
appropriate to propose a standard at 5 g/L, because at this 
level it is more likely that the total risk would be within the target 
range than at a higher standard. However, between now and promulgation 
of the final rule, EPA will work to resolve as much of this uncertainty 
as possible, both in terms of quantifying risk of additional health 
endpoints (e.g., lung cancer) and in terms of reexamining conservative 
assumptions in the risk estimate. EPA requests comment on its proposed 
level of 5 g/L and on its rationale for selecting this level. 
In selecting the final level of the standard, EPA will evaluate, in 
light of comments received and any new scientific information, its 
proposed way of using its discretionary authority under section 
1412(b)(6)(A) and the total risk, costs, and benefits associated with 
each of the levels of the standard under consideration.
    EPA requests comment on other potential MCLs and which of the MCLs 
and rationales presented here best fits the statutory framework. First, 
EPA is requesting comment on setting the MCL at 10 g/L. The 
monetized costs of $164.9-$194.8 million, and monetized benefits of 
$17.9-$52.1 million for bladder cancer (plus possible lung cancer 
benefits of $19.6-$224 based on the ``What If'' scenario) are closer at 
10 g/L. The risk levels (of bladder cancer) to the exposed 
population are within the 10-4 risk range, and the 
uncertainties already discussed in Section XI.A.6. may be a basis for 
inferring lower expected possible non-monetized benefits than assumed 
for the MCL option of 5 g/L.
    EPA is also requesting comment on an MCL option of 20 g/L. 
Some stakeholders favor an MCL in this range and cite, as justification 
for such a level, their belief that if all uncertainties are taken into 
consideration, risk estimates would be within the Agency's risk range 
of range of 1  x  10-6 to 1  x  10-4. As can be 
seen from Table XI-1, costs are considerably reduced at this level, 
since far fewer CWSs would be impacted (i.e., occurrence of arsenic, 
without treatment, is already below this level for many systems). 
Approximately 1,200 CWSs would be projected to incur costs of 
approximately $63-$77 million to

[[Page 38952]]

comply with an MCL of 20 g/L. Benefits would also be 
considerably lower than for other options, at $7.9-$29.8 million for 
bladder cancer (plus possibly $8.8-$128 million for lung cancer, based 
on the ``What If'' scenario). EPA's principal concern with an MCL 
option in this range is that it may not be sufficiently protective 
after consideration of all health endpoints of concern. In other words, 
when the effects of bladder cancer, lung cancer, and skin cancer are 
considered, together with the various non-quantifiable endpoints such 
as circulatory system impacts, an MCL option of 20 g/L could 
result in an unacceptably high risk, well outside of the risk range of 
1  x  10-6 to 1  x  10-4. As noted above, in 
using its statutory discretion to set a standard above the feasible 
level, EPA is proposing not to set a standard that exceeds this target 
risk range. However, EPA solicits comment on an MCL option of 20 
g/L along with any supporting rationale that commenters wish 
to offer.
    EPA is also requesting comment on setting the MCL at 3 g/
L. As explained in section XI.A.1., this is the level as close to the 
MCLG as is feasible. It is also the level at which the risks are most 
solidly within the 10-4 risk range of the three MCLs 
considered. If EPA were to set the MCL at this level, EPA would not use 
its discretionary authority to set the MCL at a less stringent level 
based on costs and benefits. The Agency estimates that the likelihood 
that actual monetized benefits of $43.6-$104.2 million for bladder 
cancer (plus possible lung cancer benefits of $47.2-$448 million based 
on the ``What If'' scenario), are close to monetized costs of $644.6-
$756.3 million is less certain than at 5 g/L. (See Table XI-
1.) While EPA believes that benefits may be substantially less than 
monetized costs for the feasible level, the feasible level would be the 
most protective of the options presented here and would conservatively 
account for the uncertainties about the severity of various health 
effects endpoints and their potential additive impacts.
    Finally, Congress indicated interest in assuring that EPA 
considered impacts of an MCL decision on people served by large systems 
who could afford protective MCLs and an MCL of 3 would respond to this 
interest. Section 1412(b)(6)(B), however, provides that the interests 
of people served by large systems are to be considered along with 
benefits and costs to systems not expected to get small system 
variances. Because this proposal does not include small system variance 
technologies (i.e., affordable technologies for small systems at the 
proposed MCL have been identified), the interests of persons served by 
large and small systems are being considered together and the 
provisions of section 1412(b)(6)(B) do not apply in this case.

B. Why Is EPA Proposing a Total Arsenic MCL?

    The previous drinking water standard for arsenic of 0.05 mg/L was 
based on total arsenic. Total arsenic includes the dissolved and 
undissolved arsenic species present in drinking water and makes no 
distinction between inorganic or organic species. Consistent with the 
previous standard for arsenic, today's proposed regulation of 0.005 mg/
L will be based on total arsenic. From an occurrence and analytical 
methods standpoint, the Agency believes it is inappropriate to make a 
regulatory distinction between inorganic and organic arsenic forms in 
drinking water.
    According to Irgolic (1994) and as mentioned in section II.B, the 
inorganic arsenic species (As III and As V) are present in drinking 
water, and organic arsenic compounds are rarely found in water 
supplies. Furthermore, inorganic As V (arsenate) is more prevalent in 
drinking water supplies than inorganic As III (arsenite), which tends 
to occur in anaerobic waters. If organic species are present in 
drinking water, methylarsonic acid (MMA) and dimethylarsonic acid (DMA) 
are the predominant organic forms. These organic species, when present, 
can result from the leaching of arsenic-containing herbicides or from 
the conversion of the inorganic forms to the organic forms in the 
presence of microbial activity. In arsenic-rich ground water wells from 
Taiwan, methylated compounds were not present above concentrations of 1 
g/L. No DMA or MMA was detected in the ground water samples 
from six districts in West Bengal, India (Chatterjee et al.,1995). 
Regarding surface water, Anderson and Bruland (1991) reported that 
organic species (DMA and MMA) accounted for 1 to 59% of the total 
arsenic concentration from fourteen lake and river samples taken in 
California. As Irgolic pointed out in his review of the Anderson and 
Bruland study, the level of the organic arsenic found in these surface 
water samples were in the low nanomolar (nM or nm/L) range. After 
converting the reported units from nm/L to g/L, analysis of 
the Anderson and Bruland data indicate that only two of the fourteen 
water samples exceeded a concentration of 1 g/L of organic 
arsenic (DMA and MMA combined).
    There is currently no EPA approved method for arsenic analysis in 
drinking water that distinguishes inorganic arsenic species from 
organic arsenic forms. The method would need to meet the criteria 
listed in section VI.B. and would require interlaboratory studies for 
validation. The estimated costs of such an analytical method could 
range from $150 to $250 per analysis. In addition, laboratory capacity 
for this type of method would most likely be limited at this time.
    Few toxicity studies exist for organic arsenicals. The NRC report 
noted that methylated arsenic has less developmental toxicity than 
inorganic arsenic. Concentrations of DMA administered that decreased 
fetal weight produced over 50% maternal mortality in studies with rats 
and mice (Rogers et al., 1981 as reported in NRC, 1999); hamsters had 
no developmental toxicity from exposure to MMA nor DMA (Willhite, 1981, 
as reported in NRC, 1999). NRC noted that EPA has two unpublished 
studies of rats fed MMA which had some increase in thyroid tumors, but 
no effect on mice. In addition, MMA and DMA produced mutations in cells 
at concentrations over one thousand times higher than the 
concentrations of inorganic arsenite and arsenate (Moore et al., 1997 
as reported in NRC, 1999). It takes roughly ten times more DMA than 
arsenite to cause chromosome changes in a human cell line (Oya-Ohata et 
al., 1996, as reported in NRC, 1999).
    Because of the limited occurrence of organic arsenic species in 
water and the lack of a suitable and widely available analytical method 
for inorganic arsenic, the Agency believes compliance with the proposed 
arsenic standard of 0.005 mg/L should be based on total arsenic. EPA 
requests comments on setting the MCL based on total arsenic and any 
data or established analytical methods that would support setting an 
MCL based on inorganic arsenic.

C. Why Is EPA Proposing To Require Only Monitoring and Notification for 
NTNCWSs?

    In this rulemaking, the Agency is soliciting comment on an approach 
which would not extend coverage of the rule to Non-Transient Non-
Community (NTNC) water systems, but would instead create an 
intermediate level of control for these systems (monitoring and 
notification requirements). The suggested approach would recognize the 
lower level of risk generally posed to individuals by these systems. 
Simultaneously, it would provide a mechanism for the public to be 
adequately informed in those situations where unusual concentrations of 
NTNC systems, customer overlap, and high

[[Page 38953]]

local arsenic water concentrations caused risk levels to more closely 
approach community water system levels.
    There are approximately 20,000 NTNCs water systems regulated under 
the Safe Drinking Water Act. By definition, these systems do not serve 
over 25 people as year round residents, as would be the case for a 
community water system. However, they must serve at least 25 of the 
same people for over six months out of the year, or they would be 
classified as Transient Non-Community (TNC) water systems. It is 
generally an important distinction since the Agency has not applied 
regulations for contaminants with chronic health effects to TNC water 
systems, while it often has regulated NTNC systems similar to community 
water systems when addressing the risks posed by chronic contaminants.
    In the case of arsenic, the existing regulation does not apply to 
NTNC systems. While it is feasible to control arsenic in NTNC water 
systems, extending regulation to these systems needs to be considered 
in light of the new SDWA requirement to determine whether the benefits 
extending coverage to this category would justify the costs and whether 
such regulation would provide a reasonable opportunity for health risk 
reduction. As discussed elsewhere in the preamble, this analysis 
requires a balancing of both quantitative and non-quantitative factors. 
Based on the modeling to be discussed, the ninetieth percentile 
lifetime risk of contracting bladder cancer posed to an individual 
consuming water from a NTNC water system, even in their present 
untreated state, does not exceed one in 100,000.\ 3\ As a consequence, 
costs per each bladder cancer case avoided at the proposed MCL would 
approach the fifty million dollar mark if coverage of the rule were 
extended to NTNCs. This level is well above the range of historical 
environmental risk management decisions.
---------------------------------------------------------------------------

    \3\ Throughout this discussion, exposures and risks were only 
considered for populations potentially addressable by regulation, 
i.e., systems with present arsenic levels in excess of 3 g/
L.
---------------------------------------------------------------------------

    These much lower risk levels result because most individuals served 
by NTNC systems are expected to receive only a small portion of their 
lifetime drinking water exposure from such systems. For example, even 
with twelve years of perfect attendance at schools served by NTNC water 
systems, the water consumed by an individual student is estimated to 
represent less than five percent of lifetime consumption.
    On the other hand, there are some segments of the NTNC water system 
population where exposure is a more significant portion of the total 
lifetime exposure. Manufacturing and other workers, although they 
represent only five percent of the population served by NTNC systems, 
could receive twenty to forty percent of their lifetime exposure at 
work. Nevertheless, as manufacturing workers represent a small portion 
of the NTNC population, overall risks among the NTNC population are 
small.
    Another factor of potential concern is the extent to which users of 
the different NTNC water systems overlap. It is conceivable that some 
areas in the country exist where individuals are subjected to arsenic 
exposure at a number of different non-community systems (e.g., day care 
center plus school plus factory, etc.). In such circumstances, 
individuals would be exposed to proportionately higher risks if the 
water systems all had elevated arsenic levels. For some individuals, 
the exposure could approach levels observed in corresponding community 
water systems. This concern is alleviated by the fact that NTNC systems 
generally serve only a very small portion of the total population. For 
example, over ninety-five percent of all school children are served by 
community water systems. Only a small percentage are served by NTNC 
water systems and, of that group, only about twelve percent (or less 
than one half of one percent of the overall student population) would 
be expected to have arsenic in their water above the proposed 
regulatory level). Likewise, less than 0.1 percent of the work force 
population receive water from an NTNC water system. With such low 
portions of the total population exposed to any particular type of NTNC 
system, the overall likelihood of multiple exposure cases in the NTNC 
population should also be small. The groups have been treated 
independently for this analysis. Comment and data are solicited to 
support any alternative treatments of the exposure data.
    Finally, although the Agency does not believe there is sufficient 
evidence to support unusual sensitivity on the part of children, they 
generally do consume more water on a weight adjusted basis. For this 
reason, NTNC systems which were likely to pose the greatest exposure 
risk to children were separately examined and their higher relative 
doses considered in the modeling effort. All of these factors 
contributed to the Agency's evaluation of whether or not to extend 
regulation to NTNC water systems for arsenic and are discussed further 
in the results section.
1. Methodology for Analyzing NTNCWS Risks
    Determination of system and individual exposure factors--In the 
past, the Agency has directly used SDWIS population estimates for 
assessing the risks posed to users of NTNC water systems. In other 
words, it was assumed that the same person received the exposure on a 
year round basis. Under this approach it was generally assumed that all 
NTNC users were exposed for 270 days out of the year and obtained fifty 
percent of their daily consumption from these systems. TNC users were 
assumed to use the system for only ten days per year.
    With the recent completion of ``Geometries and Characteristics of 
Public Water Systems (US EPA, 1999e),'' however, the Agency has 
developed a more comprehensive understanding of NTNC water systems. 
These systems provide water in due course as part of operating another 
line of business. Many systems are classified as NTNC, rather than TNC, 
water systems solely because they employ sufficient workers to trigger 
the ``25 persons served for over six months out of the year'' 
requirement. Client utilization of these systems is actually much less 
and more similar to exposure in TNC water systems. For instance, it is 
fairly implausible that highway rest areas along interstate highways 
serve the same population on a consistent basis (with the exception of 
long distance truckers). Nevertheless, there are highway rest areas in 
both NTNC and TNC system inventories. The ``Geometries'' report 
suggests that population figures reported in SDWIS which have been used 
for past risk assessments generally appear to reflect the number of 
workers in the establishment coupled with peak day customer 
utilization.
    Under these conditions use of the SDWIS figures for population 
greatly overestimates the actual individual exposure risk for most of 
the exposed population and also significantly underestimates the number 
of people exposed to NTNC water.\4\ Adequately characterizing 
individual and

[[Page 38954]]

population risks necessitates some adjustments to the SDWIS population 
figures. For chronic contaminants, such as arsenic, health data reflect 
the consequences of a lifetime of exposure. Consequently, risk 
assessment requires the estimation of the portion of total lifetime 
drinking water consumption that any one individual would receive from a 
particular type of water system. In turn, one needs to estimate the 
appropriate portions for daily, days per year, and years per lifetime 
consumption. These estimates need to be prepared for both the workers 
at the facility and the ``customers'' of the facility.
---------------------------------------------------------------------------

    \4\ For example, airports constitute only about a hundred of the 
NTNC water systems. Washington's Reagan National and Dulles, Dallas/
Fort Worth, Seattle/Tacoma, and Pittsburgh airports are the five 
largest of the airports. SDWIS reports that these five airports 
serve about 300,000 people. In actuality, Bureau of Transportation 
Statistics suggest that they serve about eleven million passengers 
per year. Examination of this information and other BTS statistics 
suggests that these airports serve closer to seven million unique 
individuals over the course of a year and that exposure occurs on an 
average of ten times per year per individual customer, not 270 
times.
---------------------------------------------------------------------------

    This adjustment was accomplished through a comprehensive review of 
government and trade association statistics on entity utilization by 
the U.S. Department of Commerce's Standard Industrial Classification 
(SIC) code. These figures, coupled with SDWIS information relating to 
the portion of a particular industry served by non-community water 
systems, made possible the development of two estimates needed for the 
risk assessment: customer cycles per year and worker per population 
served per day. These numbers are required to distinguish the more 
frequent and longer duration exposure of workers from that of system 
customers.\5\ A more detailed characterization of the derivation of 
these numbers is contained in the docket. Table XI-2 provides the 
factors used in the NTNC risk assessment to account for the 
intermittent nature of exposure. Comment is solicited on the 
appropriateness of the various factors.
---------------------------------------------------------------------------

    \5\ For example, travel industry statistics provide information 
on total numbers of hotel stays, vacancy rates, traveller age 
ranges, and average duration of stay. These figures can be combined 
with the SDWIS peak day population estimates to allocate daily 
population among workers, customers and vacancies. The combination 
of these factors provides an estimate of the number of independent 
customer cycles experienced in a year.
---------------------------------------------------------------------------

    Once the population adjustment factors were derived, it was 
possible to determine the actual population served by NTNC water 
systems. Table XI-3 provides a breakout of these figures by type of 
establishment. Although not included in Table XI-3, there are other 
equally important characteristics to note about these systems. With 
notable exceptions (such as the airports in Washington, DC and 
Seattle), the systems generally serve a fairly small population on any 
given day. In fact, 99 percent of the systems serve less than 3300 
users on a daily basis. This means that water production costs will be 
relatively high on a per gallon basis.
    Risk calculation--Calculations of individual risk were prepared for 
each industrial sector. Even within a given sector, however, risk 
varies as a function of an individual's relative water consumption, 
body weight, vulnerability to arsenic exposure, and the water's arsenic 
concentration. Computationally, risks were estimated by performing 
Monte Carlo modeling, as was done in the community water system risk 
estimation, with two exceptions. First, each realization in a given 
sector was multiplied by the portion of lifetime exposure factor 
presented in Table XI-2 to reflect the decreased consumption associated 
with the NTNC system. Secondly, relative exposure factors were limited 
to age specific ratings where appropriate.\6\ For example, in the case 
of school children, water consumption rates and weights for six to 
eighteen year olds were used.
---------------------------------------------------------------------------

    \6\ For example, school kid water consumption was weighted to 
reflect consumption between ages 6 and 18, while factory worker 
consumption was weighted over ages 20 to 64.

                                             Table XI-2.--Exposure Factors Used in the NTNC Risk Assessment
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                 Number of                   Worker                    Worker      Customer                   Customer
                    NTNCWS                       cycles per  Worker/pop/    fraction   Worker days/   exposure     fraction   Days of use/    exposure
                                                     yr          day         daily          yr         years        daily          yr           years
--------------------------------------------------------------------------------------------------------------------------------------------------------
Water wholesalers.............................         1.00        0.000                                                0.25         270            70
Nursing homes.................................         1.00        0.230         0.50          250           40         1.00         365            10
Churches......................................         1.00        0.010         0.50          250           40         0.50          52            70
Golf/country clubs............................         4.50        0.110         0.50          250           40         0.50          52            70
Food retailers................................         2.00        0.070         0.50          250           40         0.25         185            70
Non-food retailers............................         4.50        0.090         0.50          250           40         0.25          52            70
Restaurants...................................         2.00        0.070         0.50          250           40         0.25         185            70
Hotels/motels.................................        86.00        0.270         0.50          250           40         1.00           3.4          40
Prisons/jails.................................         1.33        0.100         0.50          250           40         1.00         270             3
Service stations..............................         7.00        0.060         0.50          250           40         0.25          52            54
Agricultural products/services................         7.00        0.125         0.50          250           40         0.25          52            50
Daycare centers...............................         1.00        0.145         0.50          250           10         0.50         250             5
Schools.......................................         1.00        0.073         0.50          200           40         0.50         200            12
State parks...................................        26.00        0.016         0.50          250           40         0.50          14            70
Medical facilities............................        16.40        0.022         0.50          250           40         1.00           6.7          10.3
Campgrounds/RV................................        22.50        0.041         0.50          180           40         1.00           5            50
Federal parks.................................        26.00        0.016         0.50          250           40         0.50          14            70
Highway rest areas............................        50.70        0.010         0.50          250           40         0.50           7.2          70
Misc. recreation service......................        26.00        0.016         0.50          250           40         1.00          14            70
Forest Service................................        26.00        0.016         1.00          250           40         1.00          14            50
Interstate carriers...........................        93.00        0.304         0.50          250           40         0.50           2            70
Amusement parks...............................        90.00        0.180         0.50          250           10         0.50           1            70
Summer camps..................................         8.50        0.100         1.00          180           10         1.00           7            10
Airports......................................        36.50        0.308         0.50          250           40         0.25          10            70
Military bases................................                     1.000         0.50          250           40
Non-water utilities...........................                     1.000         0.50          250           40
Office parks..................................                     1.000         0.50          250           40
Manufacturing: Food...........................                     1.000         0.50          250           40
Manufacturing: Non-food.......................                     1.000         0.50          250           40
Landfills.....................................                     1.000         1.00          250           40
Fire departments..............................                     1.000         1.00          250           40

[[Page 38955]]

 
Construction..................................                     1.000         1.00          250           40
Mining........................................                     1.000         1.00          250           40
Migrant labor camps...........................                     1.000         1.00          250           40
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                         Table XI-3.--Composition of Non-Transient, Non-Community Water Systems
                                                 [Percentage of total NTNC population served by sector]
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
Schools..............................      9.7  Medical Facilities......       8    Interstate Carriers.....      7.1  Campgrounds.............      1.3
Manufacturing........................      2.7  Restaurants.............       0.9  State Parks.............      8.6  Misc Recreation.........      1.8
Airports.............................     26.1  Non-food Retail.........       1.6  Amusement Parks.........     17.7  Other...................      3.5
Office Parks.........................      0.6  Hotels/Motels...........       9.2  H'way Rest Area.........      1.0
--------------------------------------------------------------------------------------------------------------------------------------------------------

    To illustrate the process, it was conservatively assumed that a 
child would attend only NTNC served schools for all twelve years. 
Further, it was assumed that a child would get half of their daily 
water consumption at school (for an average first grader this would 
correspond to roughly nine ounces of water per school day). Finally, it 
was assumed that the child would have perfect attendance and attend 
school for 200 days per year. Table XI-4 provides a sample output for 
the upper bound individual risk distribution to school children 
resulting from exposure to the range of untreated arsenic observed in 
community ground water systems \7\ as well as an estimate based on more 
moderate assumptions of four ounces per day and 150 days attendance for 
four years. Upper and lower bound risk distributions were prepared for 
both workers and ``customers'' at all types of NTNC water systems and 
are contained in the docket.
---------------------------------------------------------------------------

    \7\ Community ground water occurrence information was used since 
NTNC systems are almost exclusively supplied by ground water 
sources. Further, as there was no depth dependence of arsenic levels 
observed in the community information, it is believed that the data 
are an adequate approximation.

   Table XI-4.--Upper Bound School Children Risk Associated With Current
                 Arsenic Exposure in NTNC Water Systems
             [Risks are per 10,000 students. i.e.,  x  10-4]
------------------------------------------------------------------------
                                             Moderate
                                             exposure       Upper bound
                                             scenario        scenario
------------------------------------------------------------------------
Mean Lifetime Risk......................          0.0087           0.079
90th Percentile Lifetime Risk...........          0.019            0.17
Lifetime Bladder Cancers in Student               0.5              4.5
 Population.............................
------------------------------------------------------------------------
Note: This table does not include potential non-quantified lung or skin
  cancers.

    The distribution of population risks overall was determined as part 
of the same simulation by developing sector weightings to reflect the 
total portion of the NTNC population served by each sector. Population 
weighted proportional sampling of the individual sectors provided an 
overall distribution of risk among those exposed at NTNC systems.
2. Results
    It is important to note that the results presented in the 
discussion of NTNC benefits are based on the currently quantified 
health endpoint for arsenic related bladder cancer. As noted elsewhere 
in Section X of today's proposal, there are a number of health end 
points that have not yet been quantified and which could provide a 
rationale for extending coverage to NTNCs--in the event that a 
substantial portion of the consumers of water from such systems fall 
outside the 1 in 10,000 risk range frequently used by the Agency as a 
benchmark for such decisions. (Any additional data quantifying such 
endpoints would made available for public comment in a Notice of Data 
Availability.)
    Table XI-5 presents a summary of the Benefit Cost Analysis for all 
NTNC systems. As can be seen from a review of the Table, regulation of 
arsenic in NTNC water systems provides only very limited opportunity 
for national risk reduction. Table XI-6 presents risk figures for three 
particular sets of individuals: children in daycare centers and 
schools, and construction workers. Construction and other strenuous 
activity workers comprise an extremely small portion of the population 
served by NTNC systems (less than 0.1%), but face the highest relative 
risks of all NTNC users (90th percentile risks of 0.7 to 1.6  x  
10-4 lifetime risk). Nevertheless, there is considerable 
uncertainty about these exposure numbers. It is quite likely that they 
overestimate consumption and may be revised downward by subsequent 
analysis (Any additional data quantifying such endpoints would made 
available for public comment in a Notice of Data Availability.). The 
risks for children are much lower with an upper bound, 90th percentile 
estimate of 1.7  x  10-5 lifetime risk.
    What is not possible to determine from the analysis of NTNC systems 
is the extent to which there is overlap of individual exposure between 
the various sectors. As mentioned earlier, NTNC establishments 
generally constitute a small portion of their SIC sectors. This fact 
and the observation that NTNC populations would only serve about one 
percent of the total population if all of the sectors with significant 
exposure (greater than five percent of lifetime) if they were

[[Page 38956]]

mutually exclusive,\ 8\ provide some support for treating the SIC 
groups independently. However, it is equally plausible that there are 
communities where one individual might go from an NTNC day care center 
to a series of NTNC schools and then work in an NTNC factory.
---------------------------------------------------------------------------

    \8\ This is considerably less than the estimated rural 
population in the U.S. which is the smallest group among which users 
of these systems would conceivably be distributed.
---------------------------------------------------------------------------

    The Agency is concerned about the potential for local issues to 
arise with respect to combined arsenic exposures. In the rare community 
where all ground water is contaminated with the highest levels of 
arsenic, risks could be outside of the Agency's traditionally allowable 
realm. Further, different levels of protection being provided by 
schools served by community water systems versus those served by NTNC 
systems could be seen as posing equity considerations for rural 
communities. For all of these reasons, the Agency does not believe it 
is appropriate to completely exempt NTNC systems from arsenic 
regulation. On the other hand, it does not believe an adequate basis 
exists to prescribe a standard.
    The Agency is proposing to take a somewhat different approach with 
respect to NTNC water systems than previously practiced. We are 
proposing that NTNC water systems be subject to arsenic monitoring 
requirements applicable to community water systems. When an individual 
NTNC system has arsenic present in excess of the MCL for community 
systems, it would be required to post a notice to customers as 
described in Section VII.I. of this rule. The Agency believes that this 
approach will provide localities with high arsenic concentrations the 
opportunity to limit their consumption of water from these systems. 
Because the NTNC is not the sole source of water available to these 
consumers as would be the case with a community water system, they 
would have the ability to use bottled water, or in the case of schools 
for instance, to install voluntary treatment to reduce their exposure.
    The Agency requests comment on this approach for addressing NTNC 
water systems as well as on two other possible approaches: exempting 
NTNC systems entirely from coverage under this rule or extending 
coverage to NTNC systems in the same manner as CWSs. EPA requests an 
accompanying rationale and any data commenters wish to submit as part 
of their comments on this topic. The Agency may decide, as part of the 
final rule, to incorporate any of these three approaches without 
further opportunity for comment (except where a NODA may be issued to 
provide the public with additional new information not taken into 
consideration for today's rulemaking).

                                             Table XI-5.--Non-Transient Non-Community Benefit Cost Analysis
                                                      [All risk values are per 10,000-i.e., 10-\4\]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                        Untreated                10                     5                     3
                                                                 ---------------------------------------------------------------------------------------
                           MCL option                               Lower      Upper      Lower      Upper      Lower      Upper      Lower      Upper
                                                                    bound      bound      bound      bound      bound      bound      bound      bound
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mean Individual Risk............................................      0.019      0.042      0.012      0.026     0.0077      0.017     0.0046      0.01
90th Percentile Individual......................................      0.037      0.08       0.027      0.058     0.017       0.037     0.01        0.022
Annual Bladder Cancers..........................................      0.427      0.95       0.265      0.583     0.16        0.36      0.101       0.215
Cancer Cases Avoided............................................      0          0          0.162      0.367     0.267       0.59      0.326       0.735
Benefit Million Dollars.........................................      0          0          0.31       0.70      0.51        1.1       0.62        1.4
Cost Million Dollars............................................  .........      0      .........      6.121  .........     14.69   .........     25.21
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: This table does not include potential non-quantified lung cancer benefits.


         Table XI-6.--Sensitive Group Evaluation Lifetime Risks
------------------------------------------------------------------------
                                                        90th percentile
               Group                    Mean risk             risk
------------------------------------------------------------------------
Forest Service, Construction and       3.2-7 x 10-\5\    7.2-16 x 10-\5\
 Mining Workers...................
School Children...................   3.8-7.9 x 10-\6\  0.84-1.7 x 10-\5\
Day Care Children.................   3.4-6.8 x 10-\6\  0.74-1.5 x 10-\5\
------------------------------------------------------------------------

XII. State Programs

A. How Does Arsenic Affect a State's Primacy Program?

    States must revise their programs to adopt any part of today's rule 
which is more stringent than the approved State program. Primacy 
revisions must be completed in accordance with 40 CFR 142.12, and 
142.16. States must submit their revised primacy application to the 
Administrator for approval. State requests for final approval must be 
submitted to the Administrator no later than 2 years after promulgation 
of a new standard unless the State requests and is granted an 
additional 2-year extension.
    For revisions of State programs, Sec. 142.12 requires States to 
submit, among other things, ``[a]ny additional materials that are 
listed in Sec. 142.16 of this part for a specific EPA regulation, as 
appropriate (Sec. 142.12(c)(1)(ii)).'' Based on comments from 
stakeholders at the arsenic in drinking water regulatory development 
meetings held prior to proposal, EPA believes that the information 
required in Sec. 142.16(e) is not required for States revising the MCL 
for arsenic. Although that section refers to applications that adopt 
requirements of Secs. 141.11, 141.23, 141.32, and 141.62, EPA believes 
that existing State programs which contain the standardized monitoring 
framework for inorganic contaminants (40 CFR 141.23) can ensure all 
CWSs monitor for arsenic. Therefore, EPA is proposing to clarify that 
Sec. 141.16(e) applies only to new contaminants, not revisions of 
existing contaminants regulations. The Agency requests comment on 
whether this is an appropriate change.
    EPA believes that the requirements in Sec. 142.12(c) will provide 
sufficient information for EPA review of the State revision. The side-
by-side comparison of requirements required in Sec. 142.12(c)(1)(i) 
will only consist of sections revised to adopt the changes required for 
the arsenic regulation and

[[Page 38957]]

any other revisions requested by the State. In addition, the Attorney 
General's statement required in Sec. 142.12(c)(1)(iii) will certify 
that the revised regulations will be effective and enforceable. The 
Agency requests comment on whether any other documentation is necessary 
to approve revisions to State programs enforcing the new arsenic 
regulation.
    The Agency is proposing to add Sec. 142.16(j) to clarify primacy 
requirements relating to monitoring plans and waiver procedures for 
revisions of existing monitoring requirements such as arsenic. Section 
142.16(j) clarifies that the State simply needs to inform the Agency in 
their application of any changes to the monitoring plans and waiver 
procedures. Alternatively, a State may indicate in the primacy 
application that they will use the existing monitoring plans and waiver 
criteria approved for primacy under the National Primary Drinking Water 
Standards for other contaminants (for example, i.e. the Phase II/V 
rules). This information may be provided in the primacy application 
crosswalk which identifies revisions to the State primacy program.

B. When Does a State Have To Apply?

    To maintain primacy for the Public Water Supply (PWS) program and 
to be eligible for interim primacy enforcement authority for future 
regulations, States must adopt today's rule, when final. A State must 
submit a request for approval of program revisions that adopt the 
revised MCL and implementing regulations within two years of 
promulgation unless EPA approved an extension per Sec. 142.12(b). 
Interim primacy enforcement authority allows States to implement and 
enforce drinking water regulations once State regulations are effective 
and the State has submitted a complete and final primacy revision 
application. To obtain interim primacy, a State must have primacy with 
respect to each existing NPDWR. Under interim primacy enforcement 
authority, States are effectively considered to have primacy during the 
period that EPA is reviewing their primacy revision application.

C. How Are Tribes Affected?

    Currently, no federally recognized Indian tribes have primacy to 
enforce any of the drinking water regulations. EPA Regions implement 
the rules for all Tribes under section 1451(a)(1) of SDWA. Tribes must 
submit a primacy application to have oversight for the inorganic 
contaminants (i.e., the Phase II/V rule) to obtain the authority for 
the revised arsenic MCL. Tribes with primacy for drinking water 
programs are eligible for grants and contract assistance (section 
1451(a)(3)). Tribes are also eligible for grants under the Drinking 
Water State Revolving Fund Tribal set aside grant program authorized by 
section 1452(i) for public water system expenditures.

XIII. HRRCA

A. What Are the Requirements for the HRRCA?

    Section 1412(b)(3)(C) of the 1996 Amendments requires EPA to 
prepare a Health Risk Reduction and Cost Analysis (HRRCA) in support of 
any NPDWR that includes an MCL. According to these requirements, EPA 
must analyze each of the following when proposing a NPDWR that includes 
an MCL: (1) Quantifiable and non-quantifiable health risk reduction 
benefits for which there is a factual basis in the rulemaking record to 
conclude that such benefits are likely to occur as the result of 
treatment to comply with each level; (2) quantifiable and non-
quantifiable health risk reduction benefits for which there is a 
factual basis in the rulemaking record to conclude that such benefits 
are likely to occur from reductions in co-occurring contaminants that 
may be attributed solely to compliance with the MCL, excluding benefits 
resulting from compliance with other proposed or promulgated 
regulations; (3) quantifiable and non-quantifiable costs for which 
there is a factual basis in the rulemaking record to conclude that such 
costs are likely to occur solely as a result of compliance with the 
MCL, including monitoring, treatment, and other costs, and excluding 
costs resulting from compliance with other proposed or promulgated 
regulations; (4) the incremental costs and benefits associated with 
each alternative MCL considered; (5) the effects of the contaminant on 
the general population and on groups within the general population, 
such as infants, children, pregnant women, the elderly, individuals 
with a history of serious illness, or other subpopulations that are 
identified as likely to be at greater risk of adverse health effects 
due to exposure to contaminants in drinking water than the general 
population; (6) any increased health risk that may occur as the result 
of compliance, including risks associated with co-occurring 
contaminants; and (7) other relevant factors, including the quality and 
extent of the information, the uncertainties in the analysis, and 
factors with respect to the degree and nature of the risk.
    This analysis summarizes EPA's estimates of the costs and benefits 
associated with various arsenic levels. Summary tables are presented 
that characterize aggregate costs and benefits, impacts on affected 
entities, and tradeoffs between risk reduction and compliance costs. 
This analysis also summarizes the effects of arsenic on the general 
population as well as any sensitive subpopulations and provides a 
discussion on the uncertainties in the analysis and any other relevant 
factors.

B. What Are the Quantifiable and Non-Quantifiable Health Risk Reduction 
Benefits?

    Arsenic ingestion has been linked to a multitude of health effects, 
both cancerous and non-cancerous. These health effects include cancer 
of the bladder, lungs, skin, kidney, nasal passages, liver, and 
prostate. Arsenic ingestion has also been attributed to cardiovascular, 
pulmonary, immunological, neurological, endocrine, and reproductive and 
developmental effects. A complete list of the arsenic-related health 
effects reported in humans is shown in Table X-1. Current research on 
arsenic exposure has only been able to define scientifically defensible 
risks for bladder cancer. Because there is currently a lack of strong 
evidence on the risks of other arsenic-related health effects noted 
above, the Agency has based its assessment of the quantifiable health 
risk reduction benefits solely on the risks of arsenic induced bladder 
cancers. It is important to note that if the Agency were able to 
quantify additional arsenic-related health effects, the quantified 
benefits estimates may be significantly higher than the estimates 
presented in this analysis.
    The quantifiable health benefits of reducing arsenic exposures in 
drinking water are attributable to the reduced number of fatal and non-
fatal cancers, primarily of the bladder. Table XIII-1 shows the health 
risk reductions (number of total bladder cancers avoided and the 
proportions of fatal and non-fatal bladder cancers avoided) at various 
arsenic levels.

[[Page 38958]]



                    Table XIII-1.--Risk Reduction From Reducing Arsenic in Drinking Water \1\
----------------------------------------------------------------------------------------------------------------
                                                                                                  Risk reduction
                                                                  Risk reduction  Risk reduction    (non-fatal
                                                                  (total bladder  (fatal bladder      bladder
                 Arsenic level \2\(g/L)                      cancers         cancers         cancers
                                                                    avoided per     avoided per     avoided per
                                                                       year)           year)           year)
----------------------------------------------------------------------------------------------------------------
3...............................................................           22-42        5.7-10.9       16.3-31.1
5...............................................................           16-36         4.2-9.4       11.8-26.6
10..............................................................            9-21         2.3-5.5             296
                                                                                                        6.7-15.5
20..............................................................            4-12             1-3            3-9
----------------------------------------------------------------------------------------------------------------
\1\ The number of bladder cancer cases avoided provide our ``best'' estimates at this time. The actual number of
  cases could be lower, given the various uncertainties discussed, or higher, as these estimates assume a 100%
  mortality rate. An 80% mortality rate is used in the computation of upper bound benefits.

    The above ranges of total, fatal, and non-fatal bladder cancer 
cases are based on a range of mean bladder cancer risks for exposed 
populations at or above arsenic levels of 3, 5, 10, and 20 g/L 
as shown in Table XIII-2. For example, if we multiply the risk range at 
3 g/L (2.1  x  10-\5\ to 4.5  x  10-\5\) by the population 
exposed at 3 g/L (26.6 million), we find that the total 
cancers avoided at this arsenic level range from 22 to 42 bladder 
cancers per year, when subtracted from the number of bladder cancers 
per year at the baseline (50 g/L). Fatal bladder cancer cases 
are determined through the relationship (EPA, 1999a) that approximately 
26 percent of the total bladder cancer cases avoided at each level 
result in fatalities. Non-fatal bladder cancer cases are calculated by 
subtracting the total number of cancers from the number of fatal cancer 
cases.

    Table XIII-2.--Mean Bladder Cancer Risks and Exposed Population1
------------------------------------------------------------------------
                                                         Total bladder
   Arsenic level (g/L)        Mean exposed       cancer cases
                                    population risk 2   avoided per year
---------------------------------------------------------------3--------
Baseline (50 g/L):
    3.............................     2.1-4.5 x 10-5              22-42
    5.............................     3.6-7.5 x 10-5              16-36
    10............................    5.5-11.4 x 10-5               9-21
    20............................    6.9-13.9 x 10-5              4-12
------------------------------------------------------------------------
1 The population exposed at 3 g/L or greater is approximately
  26.6 million.
2 The bladder cancer risks presented in this table provide our ``best''
  estimates at this time. Actual risks could be lower, given the various
  uncertainties discussed, or higher, as these estimates assume a 100%
  mortality rate. An 80% mortality rate is used in the computation of
  upper bound benefits.
3 Total bladder cancer cases avoided could be higher, depending on the
  survival rate for bladder cancer in the study area of Taiwan for the
  duration of the study.

    The Agency has developed monetized estimates of the health benefits 
associated with the risk reductions from arsenic exposures. The SDWA, 
as amended, requires that a cost-benefit analysis be conducted for each 
NPDWR, and places a high priority on better analysis to support 
rulemaking. The Agency is interested in refining its approach to both 
the cost and benefit analysis, and in particular recognizes that there 
are different approaches to monetizing health benefits.
    The approach used in this analysis for the measurement of health 
risk reduction benefits is the monetary value of a statistical life 
(VSL) applied to each fatal cancer avoided. Estimating the VSL involves 
inferring individuals' implicit tradeoffs between small changes in 
mortality risk and monetary compensation. In this analysis, a central 
tendency estimate of $5.8 million (1997$) is used in the monetary 
benefits calculations. This figure is determined for the VSL estimates 
in 26 studies reviewed in EPA's recent draft guidance on benefits 
assessment (US EPA, 1997f). It is important to recognize the 
limitations of existing VSL estimates and to consider whether factors 
such as differences in the demographic characteristics of the 
populations and differences in the nature of the risks being valued 
have a significant impact on the value of mortality risk reduction 
benefits. Also, medical care or lost-time costs are not separately 
included in the benefits estimates for fatal cancers, since it is 
assumed that these costs are captured in the VSL for fatal cancers.
    For non-fatal cancers, willingness to pay (WTP) data to avoid 
chronic bronchitis is used as a surrogate to estimate the WTP to avoid 
non-fatal bladder cancers. The use of such WTP estimates is supported 
in the SDWA, as amended, at section 1412(b)(3)(C)(iii): ``The 
Administrator may identify valid approaches for the measurement and 
valuation of benefits under this subparagraph, including approaches to 
identify consumer willingness to pay for reductions in health risks 
from drinking water contaminants.''
    A WTP central tendency estimate of $536,000 (in 1997 $) is used to 
monetize the benefits of avoiding non-fatal cancers (Viscusi et al., 
1991). The fatal, non-fatal, and non-quantifiable health benefits are 
summarized in Table XIII-3. As expected, the quantified bladder cancer 
benefits increase as arsenic levels decrease.

[[Page 38959]]



                                   Table XIII-3.--Estimated Costs and Benefits From Reducing Arsenic in Drinking Water
                                                                  [In 1999 $ millions]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                      ``What if'' scenario 4 and potential non-quantified benefits
                                                                              --------------------------------------------------------------------------
                                               Total national   Total bladder    ``What if''
 Arsenic level (g/L)  Total national   costs to CWSs   cancer health    lung cancer
                                costs to CWSs   and NTNCWSs 2    benefits 3        health              Potential non-quantifiable health benefits
                                      1                                           benefits
                                                                                  estimates
--------------------------------------------------------------------------------------------------------------------------------------------------------
3............................       643.1-753     644.6-756.3      43.6-104.2        47.2-448   Skin Cancer.
                                                                       5 (79)       6 (213.4)   Kidney Cancer.
                                                                                                Cancer of the Nasal Passages.
5............................     377.3-441.8     378.9-444.9       31.7-89.9          35-384   Liver Cancer.
                                                                     5 (64.3)       6 (173.4)   Prostate Cancer.
                                                                                                Cardiovascular Effects.
10...........................     163.3-191.8     164.9-194.8       17.9-52.1        19.6-224   Pulmonary Effects.
                                                                       5 (37)         6 (100)   Immunological Effects.
20...........................       61.6-72.9       63.2-77.1        7.9-29.8         8.8-128   Neurological Effects.
                                                                     5 (19.8)        6 (53.4)   Endocrine Effects.
                                                                                                Reproductive and Developmental Effects.
--------------------------------------------------------------------------------------------------------------------------------------------------------
1 Costs include treatment, monitoring, O&M, and administrative costs to CWSs and State costs for administration of water programs. The lower number
  shows costs annualized at a consumption rate of interest of 3%, EPA's preferred approach. The higher number shows costs annualized at 7%, which
  represents the standard discount rate preferred by OMB for benefit-cost analyses of government programs and regulations.
2 Costs include treatment, monitoring, O&M, administrative costs to CWSs; monitoring and administrative costs to NTNCWSs; and State costs for
  administration of water programs.
3 The upper bound estimate includes an adjustment to account for a possible mortality risk of 80%. It is possible that this risk could have been below
  80%, which would lead to increased benefits. The actual risk depends on the survival rate for bladder cancer in the area of Taiwan studied by Chen,
  which is unknown.
4 These estimates are based on the ``what if'' scenario for lung cancer, where the risks of a fatal lung cancer case associated with arsenic are assumed
  to be 2-5 times that of a fatal bladder cancer case.
5 The number in parentheses indicates the bladder cancer health benefits assuming an 80% mortality rate for bladder cancer in the area of the Chen
  study, and starting from the midpoint of the benefits range when mortality and incidence are assumed equivalent.
6 The number in parentheses is the midpoint of the range and corresponds to an assumption that the risk of fatal lung cancer is 3.5 times the risk of
  fatal bladder cancer.

    Reductions in arsenic exposures may also be associated with non-
quantifiable benefits. EPA has identified several potential non-
quantifiable benefits associated with regulating arsenic in drinking 
water. In addition to the non-quantifiable benefits noted in Table 
XIII-3, these benefits may include any customer peace of mind from 
knowing that their drinking water has been treated for arsenic. Also, 
using reverse osmosis to remove arsenic from drinking water may also 
reduce other contaminants such as sulfate, nitrate, and iron due to the 
high removal efficiency of this treatment technology.

C. What Are the Quantifiable and Non-Quantifiable Costs?

    The costs of reducing arsenic to various levels are summarized in 
Table XIII-4, which shows that, as expected, aggregate arsenic 
mitigation costs increase with decreasing arsenic levels. Total 
national costs range from $646 million per year at 3 g/L to 
$65 million per year at 20 g/L.

                Table XIII-4.--Estimated Annualized National Costs of Reducing Arsenic Exposures
                                              [In 1999 $ millions]
----------------------------------------------------------------------------------------------------------------
                                                                       Total national     Total cost per fatal
     Arsenic level (g/L)       Costs to CWSs  Total national   costs to CWSs     bladder cancer case
                                              1         costs to CWSs   and NTNCWSs 3          avoided 4
--------------------------------------------------------------2-------------------------------------------------
3....................................       639-746.4       643.1-753     644.6-756.3        59-113 (69.4-132.7)
5....................................         374-436     377.3-441.8     378.9-444.9             40-91 (47-106)
10...................................         160-187     163.3-191.8     164.9-194.8      30.2-70.5 (35.4-84.7)
20...................................           59-68       61.6-72.9       63.2-77.1     20.3-60.7 (26-77.1)1.
----------------------------------------------------------------------------------------------------------------
1 Costs include treatment and O&M costs only. The lower number shows costs annualized at 3 percent; the higher
  number shows costs annualized at 7%. The 7% rate represents the standard discount rate preferred by OMB for
  benefit-cost analyses of government programs and regulations.
2 Costs include treatment, monitoring, O&M, and administrative costs to CWSs and State costs for administration
  of water programs. Costs annualized at 3 and 7 percent.
3 Costs include treatment, monitoring, O&M, administrative costs to CWSs; monitoring and administrative costs to
  NTNCWSs; and State costs for administration of water programs. Costs annualized at 3 and 7 percent.
4 Range based on range of fatal bladder cancer cases avoided per year shown in Table XIII.1. The range of costs
  per fatal bladder cancer avoided could be one-half of the value presented, depending on the mortality rate for
  bladder cancer in the study area of Taiwan for the duration of the study. A plausible estimate for that
  mortality rate is 80%.

    The cost impact of reducing arsenic in drinking water at the 
household level was also assessed. Table XIII-5 examines the cost per 
household for each system size category. As shown in the table, costs 
per household decrease as system size increases. Costs per household 
also do not vary significantly across arsenic levels. This is because

[[Page 38960]]

costs do not vary significantly with removal efficiency; once a system 
installs a treatment technology to meet an MCL, costs based upon the 
removal efficiency that the treatment technology will be operated under 
remain relatively flat. Per household costs are, however, somewhat 
lower at less stringent arsenic levels. This is due to the assumption 
that some systems would blend water at these levels and treat only a 
portion of the flow.

     Table XIII-5.--Estimated Annual Costs per Household \1\ (in 1999 $) and (Number of Households Affected)
----------------------------------------------------------------------------------------------------------------
                                                                                  10 g/  20 g/
                   System size                    3 g/L  5 g/L         L               L
----------------------------------------------------------------------------------------------------------------
25-100..........................................            $368            $364            $357            $349
                                                        (93,900)        (58,600)        (27,000)        (10,000)
101-500.........................................            $259            $254            $246            $238
                                                       (366,900)       (229,000)       (103,000)        (41,000)
501-1,000.......................................            $106            $104             $98             $93
                                                       (356,000)       (223,000)       (102,000)        (41,000)
1,001-3,300.....................................             $64             $60             $57             $52
                                                         \2\ (1)       (626,000)       (290,000)       (118,000)
3,301-10,000....................................             $44             $41             $37             $33
                                                       \2\ (1.6)         \2\ (1)       (478,000)       (196,000)
10,001-50,000...................................             $36             $33             $29             $25
                                                      \2\ (3.25)       \2\ (2.1)        (998,000       (406,000)
50,001-100,000..................................             $30             $27             $23             $19
                                                       \2\ (1.4)       \2\ (0.9)       (465,000)       (189,000)
100,001-1 million...............................             $23             $21             $18             $15
                                                       \2\ (3.1)       \2\ (1.8)       (937,000)      (365,000)
----------------------------------------------------------------------------------------------------------------
\1\ Costs include treatment and O&M costs to CWSs only.
\2\ Million.

    Costs per household are higher for households served by smaller 
systems than larger systems for two reasons. First, smaller systems 
serve far fewer households than larger systems and, consequently, each 
household must bear a greater percentage share of the capital and O&M 
costs. Second, smaller systems tend to have higher influent arsenic 
concentrations that, on a per-capita or per-household basis, require 
more expensive treatment methods (e.g., a higher percentage removal 
efficiency) to comply with an MCL.
    Table XIII-6 summarizes the estimates of total national costs of 
compliance with the proposed MCL options of 3, 5, and 10, and 20 
g/L. This table is divided into two major groupings; the first 
grouping displays the estimated costs to Community Water Systems (CWSs) 
and the second grouping displays the estimated costs to Non-Transient 
Non-Community Water Systems (NTNCWSs). The State costs presented in 
Table XIII-6 were developed as part of the analyses to comply with the 
Unfunded Mandates Reform Act (UMRA) and also the Paperwork Reduction 
Act (PRA). Additional information on State costs is provided in Section 
XIV of this preamble.

  Table XIII-6.--Summary of the Total Annual National Costs of Compliance With the Proposed Arsenic Rule Across
                                                   MCL Options
                                             [In 1997 $ millions] 1
----------------------------------------------------------------------------------------------------------------
                      Costs                                     CWS                           NTNCWS
----------------------------------------------------------------------------------------------------------------
                 Cost of capital                     3 percent       7 percent       3 percent       7 percent
----------------------------------------------------------------------------------------------------------------
                                                 3 g/L
----------------------------------------------------------------------------------------------------------------
Treatment.......................................           639.2           746.4        * (25.2)        * (30.5)
Monitoring, Reporting & Recordkeeping...........             2.2             2.9            0.95             1.1
State & EPA Administrative Costs................             2.2             3.7             1.1             2.2
                                                 ---------------------------------------------------------------
    Total Costs.................................           643.6           753.0    * 1.2 (27.3)    * 3.3 (33.8)
----------------------------------------------------------------------------------------------------------------
                                                 5 g/L
----------------------------------------------------------------------------------------------------------------
Treatment.......................................           373.9           436.0        * (14.7)        * (17.8)
Monitoring, Reporting & Recordkeeping...........             1.9             2.7            0.92             1.1
State & EPA Administrative Costs................             1.8             3.1             1.0             2.0
                                                 ---------------------------------------------------------------
    Total Costs.................................           377.8           441.8    * 1.2 (16.6)    * 3.1 (20.9)
----------------------------------------------------------------------------------------------------------------
                                                 10 g/L
----------------------------------------------------------------------------------------------------------------
Treatment.......................................           160.4           186.7         * (6.1)         * (7.4)
Monitoring, Reporting & Recordkeeping...........             1.8             2.5            0.90             1.1
State & EPA Administrative Costs................             1.5             2.6            0.93             1.9
                                                 ---------------------------------------------------------------
    Total Costs.................................           163.7           191.8     * 1.8 (7.9)     *3.0 (10.3)
----------------------------------------------------------------------------------------------------------------

[[Page 38961]]

 
                                                 20 g/L
----------------------------------------------------------------------------------------------------------------
Treatment.......................................            58.9            68.3         * (2.1)         * (2.6)
Monitoring, Reporting & Recordkeeping...........             1.7             2.4             2.0             2.3
State & EPA Administrative Costs................             1.3             2.3            0.91             1.9
                                                 ---------------------------------------------------------------
    Total Costs.................................            61.9            72.9     * 2.9 (5.1)    * 4.2 (6.7)
----------------------------------------------------------------------------------------------------------------
1 Totals may not add due to rounding.
* Costs in parentheses include treatment costs if NTNCWS had to comply with the MCL.

D. What Are the Incremental Benefits and Costs?

    Table XIII-7 summarizes the incremental benefits and costs 
associated with arsenic exposure reduction.

  Table XIII-7.--Estimates of the Annual Incremental Risk Reduction, Benefits, and Costs of Reducing Arsenic in
                                                 Drinking Water
                                                [$millions, 1999]
----------------------------------------------------------------------------------------------------------------
                                                  20 g/  10 g/
                  Arsenic level                          L               L        5 g/L  3 g/L
----------------------------------------------------------------------------------------------------------------
Incremental Risk Reduction, Fatal Bladder                    1-3         1.3-2.5         1.9-3.9         1.5-1.5
 Cancers Avoided Per Year.......................
Incremental Risk Reduction, Non-Fatal Bladder                3-9         3.7-6.5        5.1-11.1         4.5-4.5
 Cancers Avoided Per Year.......................
Annual Incremental Monetized Benefits \1\.......        7.9-29.8         10-22.3       13.8-37.8       11.9-14.3
Annual Incremental Costs \2\....................            63.2           101.7             214          265.7
----------------------------------------------------------------------------------------------------------------
\1\ The incremental upper bound benefits estimates presented in this table have been adjusted upwards to reflect
  an 80% mortality rate, which is a plausible mortality rate for the area of Taiwan during the Chen study.
\2\ Costs include treatment, monitoring, O&M, and administrative costs to CWSs; monitoring and administrative
  costs to NTNCWSs and State costs.

E. What Are the Risks of Arsenic Exposure to the General Population and 
Sensitive Subpopulations?

    The SDWA, as amended, includes specific provisions in section 
1412(b)(3)(C)(i)(V) to assess the effects of the contaminant on the 
general population and on groups within the general population such as 
children, pregnant women, the elderly, individuals with a history of 
serious illness, or other subpopulations that are identified as likely 
to be at greater risk of adverse health effects due to exposure to 
contaminants in drinking water than the general population. The NRC 
Report concluded that there is insufficient scientific information to 
permit separate cancer risk estimates for potential subpopulations such 
as pregnant women, lactating women, and children and that factors that 
influence sensitivity to or expression of arsenic-associated cancer and 
noncancer effects need to be better characterized. Despite the 
inconclusive nature of the effects on subpopulations, EPA is planning 
to issue a health advisory for arsenic in early 2000. See section IV.C 
of this preamble for further information on the health advisory.

F. What Are the Risks Associated With Co-Occurring Contaminants?

    The SDWA, as amended, requires EPA to take into account the 
activities under preceding rules that may have impacts on future rules. 
To address this requirement, EPA analyzed the co-occurrence of arsenic 
with other drinking water contaminants (EPA, 1999f). The results of 
this analysis help determine the level of overlap in regulatory 
requirements (cost of technology that can remove more than one 
contaminant) and also indicate where specific levels of one contaminant 
may interfere with the treatment technology for another. This analysis 
indicates that there is some co-occurrence of arsenic with sulfate, 
iron, and radon. Co-occurrence can also indicate the likelihood for 
increased, or in this case, decreased risks due to arsenic and 
selenium.
    As discussed in section XI.A.5. of the preamble, animal studies 
suggest that selenium reduces the toxicity of arsenic, and people in 
Taiwan have much lower levels of selenium in their blood and urine than 
people in China, the U.S., and Canada. Deficient selenium intake is 
linked to heart problems, and excessive intake can lead to thick 
brittle nails and changes in the nervous system. The U.S. recommends a 
daily dietary intake of 55 g/day for females and 70 
g/day for males. The WHO lower limit of safe ranges are 30 
(for females) and 40 (for males) g/day (NRC, 1990). EPA's 
study of co-occurrence of arsenic (at 2, 5, 10, 20, and > 20 
g/L) and selenium above 50 g/L levels found no 
significant correlations between arsenic and selenium. EPA believes 
that, in general, the U.S. population does not experience selenium 
toxicity which would be reduced by the presence of arsenic and that 
there is sufficient selenium in the American diet to reduce the 
toxicity of arsenic. The Agency requests data and comments on whether 
selenium decreases arsenic toxicity on a regional basis. Section V of 
this preamble summarizes the results of EPA's arsenic co-occurrence 
analysis.

G. What Are the Uncertainties in the Analysis?

    The models used to estimate arsenic-related cancer risks, risk 
reduction, and monetary benefits take many inputs which are both 
uncertain and highly variable. The benefits estimates that have been 
discussed in this preamble were derived using point estimates of

[[Page 38962]]

the monetary surrogates for fatal and non-fatal bladder cancers. The 
value of statistical life (VSL) has been approximated by a single-value 
estimate of $5.8 million, and willingness-to-pay (WTP) to avoid non-
fatal bladder cancer has been modeled as a constant with a value of 
$536,000. These are the central tendency values derived by EPA, based 
on studies from the economic literature and previous regulatory 
analyses (US EPA 1997f, Viscusi et al., 1991). Because the VSL is much 
larger than the WTP value, the VSL value dominates the total monetary 
benefits calculation.
    The studies that have been reviewed by EPA (US EPA 1997f) have 
developed a wide range of VSL values, from $700,000 to $16.3 million. 
This implies that the monetized benefits of reduced bladder cancer 
risks could take a wide range of values, depending upon the VSL that is 
chosen.
    Additional sources of uncertainty in this analysis are also found 
in the NRC Report. Such uncertainties include the shape of the dose-
response curve, the contribution of arsenic exposure from food, and the 
choice of model when conducting arsenic risk assessment. These sources 
of uncertainties are discussed in further detail in section XI. of 
today's document.

XIV. Administrative Requirements

A. Executive Order 12866: Regulatory Planning and Review

    Under Executive Order 12866, ``Regulatory Planning and Review'' (58 
FR 51735, October 4, 1993), the Agency must determine whether the 
regulatory action is ``significant'' and therefore subject to OMB 
review and the requirements of the Executive Order. The Order defines 
``significant regulatory action'' as one that is likely to result in a 
rule that may:
    (1) Have an annual effect on the economy of $100 million or more or 
adversely affect in a material way the economy, a sector of the 
economy, productivity, competition, jobs, the environment, public 
health or safety, or State, local, or tribal governments or 
communities;
    (2) Create a serious inconsistency or otherwise interfere with an 
action taken or planned by another agency;
    (3) Materially alter the budgetary impact of entitlements, grants, 
user fees, or loan programs or the rights and obligations of recipients 
thereof; or
    (4) Raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the Executive Order.
    Pursuant to the terms of Executive Order 12866, it has been 
determined that this rule is a ``significant regulatory action''. As 
such, this action was submitted to OMB for review. Changes made in 
response to OMB suggestions or recommendations will be documented in 
the public record.

B. Regulatory Flexibility Act (RFA), as Amended by the Small Business 
Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5 U.S.C. 601 et 
seq.

1. Overview
    The RFA generally requires an agency to prepare a regulatory 
flexibility analysis of any rule subject to notice and comment 
rulemaking requirements under the Administrative Procedure Act or any 
other statute unless the Agency certifies that the rule will not have a 
significant economic impact on a substantial number of small entities. 
Small entities include small businesses, small organizations, and small 
governmental jurisdictions.
2. Use of Alternative Small Entity Definition
    The RFA provides default definitions for each type of small entity. 
It also authorizes an agency to use alternative definitions for each 
category of small entity, ``which are appropriate to the activities of 
the agency'' after proposing the alternative definition(s) in the 
Federal Register and taking comment (5 U.S.C. 601(3)-(5)). In addition 
to the above, to establish an alternative small business definition, 
agencies must consult with SBA's Chief Counsel for Advocacy.
    EPA is proposing the Arsenic Rule which contains provisions which 
apply to small PWSs serving fewer than 10,000 persons. This is the cut-
off level specified by Congress in the 1996 Amendments to the Safe 
Drinking Water Act for small system flexibility provisions. Because 
this definition does not correspond to the definitions of ``small'' for 
small businesses, governments, and non-profit organizations, EPA 
requested comment on an alternative definition of ``small entity'' in 
the preamble to the proposed Consumer Confidence Report (CCR) 
regulation (63 FR 7605 at 7620, February 13, 1998, US EPA 1998j). 
Comments showed that stakeholders supported the proposed alternative 
definition. EPA also consulted with the SBA Office of Advocacy on the 
definition as it relates to small business analysis. In the preamble to 
the final CCR regulation (63 FR 44511, August 19, 1998, US EPA, 1998e), 
EPA stated its intent to establish this alternative definition for 
regulatory flexibility assessments under the RFA for all drinking water 
regulations and has thus used it in this proposed rulemaking.
3. Initial Regulatory Flexibility Analysis
    In accordance with section 603 of the RFA, EPA prepared an initial 
regulatory flexibility analysis (IRFA) that examines the impact of the 
proposed rule on small entities along with regulatory alternatives that 
could reduce that impact. The IRFA is available for review in the 
docket and is summarized below.
    The RFA requires EPA to address the following when completing an 
IRFA:
    (1) Describe the reasons why action by the Agency is being 
considered;
    (2) State succinctly the objectives of, and legal basis for, the 
proposed rule;
    (3) Describe, and where feasible, estimate the types and number of 
small entities to which the proposed rule will apply;
    (4) Describe the projected reporting, record keeping, and other 
compliance requirements of the rule, including an estimate of the 
classes of small entities that will be subject to the requirements and 
the type of professional skills necessary for preparation of reports or 
records;
    (5) Identify, to the extent practicable, all relevant Federal rules 
that may duplicate, overlap, or conflict with the proposed rule; and
    (6) Describe any significant alternatives to the proposed rule that 
accomplish the stated objectives of applicable statutes while 
minimizing any significant economic impact of the proposed rule on 
small entities.
    EPA has considered and addressed all of the previously described 
requirements. The following is a summary of the IRFA. The first and 
second requirements are discussed in section I.A. of this Preamble. The 
third and fourth requirements are summarized as follows. The fifth 
requirement is discussed under section VIII.F. of this Preamble in a 
subsection addressing potential interactions between the arsenic rule 
and upcoming and existing rules affecting community water systems. The 
sixth requirement, regulatory alternatives, is detailed in section 
XIII.
    a. Number of Small Entities Affected. The number of small entities 
subject to today's rule is shown in Table XIV-1 below.

[[Page 38963]]



          Table XIV-1.--Profile of the Universe of Small Water Systems Regulated Under the Arsenic Rule
----------------------------------------------------------------------------------------------------------------
                                                               System size category
        Water system type        -------------------------------------------------------------------------------
                                        100           101-500        501-1,000      1,001-3,300    3,301-10,000
----------------------------------------------------------------------------------------------------------------
Publicly-Owned:
    CWS.........................           1,729           5,795           3,785           6,179           3,649
    NCWS........................           1,783           3,171           1,182             361              29
Privately-Owned:
    CWS.........................          13,640          11,266           2,124           1,955             654
    NCWS........................           8,178           4,162             902             411              56
Total Systems:
    CWS.........................          15,369          17,061           5,909           8,134           4,303
    NCWS........................           9,961           7,333           2,084             772              85
                                 -------------------------------------------------------------------------------
        Total...................          25,330          24,394           7,993           8,906          4,388
----------------------------------------------------------------------------------------------------------------
Source: Safe Drinking Water Information System (SDWIS), December 1998 freeze.

    b. Reporting, Recordkeeping and Other Requirements for Small 
Systems. The proposed arsenic rule continues to require small systems 
to maintain records and to report arsenic concentration levels at the 
point-of-entry to the water system's distribution system. Small systems 
are also required to provide arsenic information in the Consumer 
Confidence Report or other public notification if the system exceeds 
the MCL. Arsenic monitoring and reporting will be required annually for 
surface water (and mixed surface and ground water systems) or once 
every three years for ground water systems, unless the small system 
obtains a monitoring waiver from the State, demonstrating compliance 
with the proposed MCL. Other existing information and reporting 
requirements, such as Consumer Confidence Reports and public 
notification requirements, will be revised to include the lower arsenic 
MCL (see sections VII. H. and I.). As is the case for other 
contaminants, required information on system arsenic levels must be 
provided by affected systems and is not considered to be confidential. 
The professional skills necessary for preparing the reports are the 
same skill level required by small systems for current reporting and 
monitoring requirements for other drinking water standards.
    The classes of small entities that are subject to the proposed 
arsenic rule include public water systems serving less than 10,000 
people.
4. Small Business Advocacy Review (SBAR) Panel Recommendations
    As required by section 609(b) of the RFA, as amended by SBREFA, EPA 
also conducted outreach to small entities and convened a Small Business 
Advocacy Review Panel to obtain advice and recommendations of 
representatives of the small entities that potentially would be subject 
to the rule's requirements.
    EPA identified 22 representatives of small entities that were most 
likely to be subject to the proposal. In December, 1998, EPA prepared 
and distributed to the small entity representatives (SERs) an outreach 
document on the arsenic rule titled ``Information for Small Entity 
Representatives Regarding the Arsenic in Drinking Water Rule'' (US EPA, 
1998g).
    On December 18, 1998, EPA held a small entity conference call from 
Washington D.C. to provide a forum for small entity input on key issues 
related to the planned proposal of the arsenic in drinking water rule. 
These issues included, but were not limited to issues related to the 
rule development, such as arsenic health risks, treatment technologies, 
analytical methods, and monitoring. Fifteen SERs from small water 
systems participated on the call from the following States: Alabama, 
Arizona, California, Georgia, Massachusetts, Montana, Nebraska, New 
Hampshire, New Jersey, Utah, Virginia, Washington, and Wisconsin.
    Efforts to identify and incorporate small entity concerns into this 
rulemaking culminated with the convening of a SBAR Panel on March 30, 
1999, pursuant to section 609 of RFA/SBREFA. The four-person Panel was 
headed by EPA's Small Business Advocacy Chairperson and included the 
Director of the Standards and Risk Management Division within EPA's 
Office of Ground Water and Drinking Water, the Administrator of the 
Office of Information and Regulatory Affairs with the Office of 
Management and Budget, and the Chief Counsel for Advocacy of the SBA. 
For a 60-day period starting on the convening date, the Panel reviewed 
technical background information related to this rulemaking, reviewed 
comments provided by the SERs, and met on several occasions. The Panel 
also conducted its own outreach to the SERs and held a conference call 
on April 21, 1999 with the SERs to identify issues and explore 
alternative approaches for accomplishing environmental protection goals 
while minimizing impacts to small entities. Consistent with the RFA/
SBREFA requirements, the Panel evaluated the assembled materials and 
small-entity comments on issues related to the elements of the IRFA. A 
copy of the June 4, 1999 Panel report is included in the docket for 
this proposed rule (US EPA, 1999c).
    Today's notice incorporates all of the recommendations on which the 
Panel reached consensus, except for a number of recommendations on 
information to include in small system guidance. The small system 
guidance materials will be provided before or soon after the final rule 
is published in the Federal Register. EPA is committed to addressing 
the following Panel recommendations regarding guidance for small 
systems: highlight the various waste disposal options and the necessary 
technical and procedural steps for small CWSs to follow in exploring 
these alternatives; provide specific recommendations and technical 
information relative to the use of POU devices; provide guidance to 
State and local authorities on waste disposal issues relative to the 
use of these devices; and provide information to assist in making 
treatment decisions to address multiple contaminants in the most cost-
effective manner. The Panel also recommended that EPA provide guidance 
identifying cost-effective treatment trains for ground water systems 
that need to treat for both arsenic and radon in the proposed rule. 
However, treatment trains cannot be accurately identified until after 
the radon and arsenic standards are finalized because these standards 
would affect which treatment technologies are appropriate. Since the 
co-occurrence of

[[Page 38964]]

arsenic and radon seems to be statistically significant in only two EPA 
regions, the impact from this co-occurring pair is not significant on a 
national level. However, for the regions which are impacted, there is 
the potential that aeration treatment technology that may be used to 
mitigate radon may also help to mitigate arsenic. Aeration technology 
can oxidize the soluble form of arsenic to the insoluble form. This 
would reduce the cost of arsenic mitigation by making it easier to 
remove arsenic. EPA will address this recommendation further in the 
small system guidance materials.
    The following is a summary of the rest of the Panel recommendations 
and EPA's response to these recommendations, by subject area:
    Treatment Technologies, Waste Disposal, and Cost Estimates: The 
Panel recommended the following: further develop the preliminary 
treatment and waste disposal cost estimates; fully consider these costs 
when identifying affordable compliance technologies for all system size 
categories; and provide information to small water systems on possible 
options for complying with the MCL, in addition to installing any 
listed compliance technologies.
    In response to these recommendations, the treatment section of the 
preamble (see section VIII.A.) and the Treatment and Cost document (US 
EPA, 1999i) describe the development of final cost estimates for 
treatment and waste disposal, including the request for comment on its 
projected household costs; how EPA identified the affordable compliance 
technologies, including the consideration of cost (section VIII.B.); 
and information has been added to the treatment section about options 
for complying with the MCL other than installing compliance 
technologies, such as selecting to regionalize (see section VIII.B.).
    Regarding POU devices, the Panel recommended the following: 
continue to promote the use of POU devices as alternative treatment 
options for very small systems where appropriate; account for all 
costs, including costs that may not routinely be explicitly calculated; 
and consider liability issues from POU/POE devices when evaluating 
their appropriateness as compliance technologies; and investigate waste 
disposal issues with POE devices.
    In response to these recommendations, the treatment section of the 
preamble: includes an expanded description regarding available POU 
compliance treatment technologies and conditions under which POU 
treatment may be appropriate for very small systems (see section 
VIII.D.); describes the components which contribute to the POU cost 
estimates (see section VIII.D.); and clarifies that water systems will 
be responsible for POU operation and maintenance to prevent liability 
issues from customers maintaining equipment themselves (see section 
VIII.D.). In addition, EPA does not recommend reverse osmosis as a POE 
treatment technology due to the evaluation of corrosion control issues 
(see section VIII.D.).
    Relevance of Other Drinking Water Regulations: The Panel 
recommended the following: include discussion of the co-occurrence of 
arsenic and radon in the proposed rule for arsenic; take possible 
interactions among treatments for different contaminants into account 
in costing compliance technologies and determining whether they are 
nationally affordable for small systems; and encourage systems to be 
forward-looking and test for the multiple contaminants to determine if 
and how they would be affected by the upcoming rules.
    In response, the co-occurrence section of the preamble includes a 
discussion on the co-occurrence analysis of radon and arsenic (see 
section V.H.), and the treatment section of the preamble has been 
expanded to describe the relationship of treatment for arsenic with 
other drinking water rules and how this issue was taken into account in 
cost estimates (see section VIII.F.). The preamble encourages systems 
to consider other upcoming rules when making future plans on monitoring 
or treatment (see section VIII.E.).
    Small Systems Variance Technologies and National Affordability 
Criteria: The Panel recommended the following: include a discussion of 
the issues surrounding appropriate adjustment of its national 
affordability criteria to account for new regulatory requirements; 
consider revising its approach to national affordability criteria to 
address the concern that the current cumulative approach for adjusting 
the baseline household water bills is based on chronological order 
rather than risk, to the extent allowed by statutory and regulatory 
requirements; and examine the data in the 1995 Community Water Supply 
Survey to determine if in-place treatment baselines can be linked with 
the current annual water bill baseline in each of the size categories 
for the proposed rule.
    In response to these recommendation, the treatment section of the 
preamble (VIII.C.) includes an expanded discussion about the national 
affordability criteria and adjusting it to account for new regulations; 
information and rationale have been added to explain the national 
affordability approach (see section VIII.C.). The 1995 Community Water 
System Survey (US EPA, 1997g) does not provide sufficient data to link 
in-place treatment baselines with annual water bill baselines.
    Monitoring and Arsenic Species: The Panel recommended that EPA 
consider allowing States to use recent compliance monitoring data to 
satisfy initial sampling requirements or to obtain a waiver and that 
EPA continue to explore whether or not to make a regulatory distinction 
between organic and inorganic arsenic based on compliance costs and 
other considerations. In response, the monitoring section of the 
preamble and the proposed regulatory language describe the allowance of 
monitoring data that meet analytical requirements and have reporting 
limits sufficiently below the revised MCL and collected after 1990. The 
MCL section of the preamble contains information and rationale to 
support EPA's decision to base the MCL on total arsenic (see section 
XI).
    Considerations in setting the MCL: The Panel recommended the 
following: in performing its obligations under SDWA, take cognizance of 
the scientific findings, the large scientific uncertainties, the large 
potential costs (including treatment and waste disposal costs), and the 
fact that this standard is scheduled for review in the future; give 
full consideration to the provisions of the Executive Order 12866 and 
to the option of exercising the new statutory authority under SDWA 
sections 1412(b)(4)(C) and 1412(b)(6)(A) in the development of the 
arsenic rule; and fully consider all of the ``risk management'' 
components of its rulemaking effort to ensure that the financial and 
other impacts on small entities are factored into its decision-making 
processes. The Panel also recommended that EPA take into account both 
quantifiable and non-quantifiable costs and benefits of the standard 
and the needs of sensitive sub-populations, and give due consideration 
to the impact of the rule upon small systems.
    In response to all these recommendations, EPA describes in detail 
the factors that were considered in setting in the MCL and provides the 
rationale for this selection (see section XI).
    Applicability of proposal: The Panel recommended that EPA carefully 
consider the appropriateness of extending the scope of the rule to Non-
Transient, Non-Community Water Systems (NTNCWSs). In response, the

[[Page 38965]]

proposed MCL for arsenic does not apply to NTNCWSs and the MCL section 
of the preamble describes the basis for this decision, including the 
incremental costs and benefits attributable to coverage of these water 
systems (see section XI.C.).
    Other Issues: The Panel recommended that EPA encourage small 
systems to discuss their infrastructure needs for complying with the 
arsenic rule with their primacy agency to determine their eligibility 
for DWSRF loans, and if eligible, to ask for assistance in applying for 
the loans. In response, the UMRA section XIV.C. has been expanded to 
discuss funding options for small systems, and guidance will be written 
to encourage systems to be proactive in communicating with their 
primacy agency.
    Regarding health effects, the Panel recommended the following: 
Further evaluate the Utah study and its relationship to the studies on 
which the NRC report was based and give it appropriate weight in the 
risk assessment for the proposed arsenic standard; and examine the NRC 
recommendations in the light of the uncertainties associated with the 
report's recommendations, and any new data that may not have been 
considered in the NRC report. In response to these recommendations, the 
benefits and MCL sections (sections X and XI) describe the quantitative 
and non-quantitative benefits evaluation and use of research data.
    We invite comments on all aspects of the proposal and its impacts 
on small entities.

C. Unfunded Mandates Reform Act (UMRA)

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public 
Law 104-4, establishes requirements for Federal agencies to assess the 
effects of their regulatory actions on State, local, and tribal 
governments and the private sector. Under UMRA section 202, EPA 
generally must prepare a written statement, including a cost-benefit 
analysis, for proposed and final rules with ``Federal mandates'' that 
may result in expenditures to State, local, and tribal governments, in 
the aggregate, or to the private sector, of $100 million or more in any 
one year. Before promulgating an EPA rule, for which a written 
statement is needed, section 205 of the UMRA generally requires EPA to 
identify and consider a reasonable number of regulatory alternatives 
and adopt the least costly, most cost-effective or least burdensome 
alternative that achieves the objectives of the rule. The provisions of 
section 205 do not apply when they are inconsistent with applicable 
law. Moreover, section 205 allows EPA to adopt an alternative other 
than the least costly, most cost-effective or least burdensome 
alternative if the Administrator publishes with the final rule an 
explanation on why that alternative was not adopted.
    Before EPA establishes any regulatory requirements that may 
significantly or uniquely affect small governments, including tribal 
governments, it must have developed, under section 203 of the UMRA, a 
small government agency plan. The plan must provide for notifying 
potentially affected small governments, enabling officials of affected 
small governments to have meaningful and timely input in the 
development of EPA regulatory proposals with significant Federal 
intergovernmental mandates and informing, educating, and advising small 
governments on compliance with the regulatory requirements.
1. Summary of UMRA Requirements
    EPA has determined that this rule contains a Federal mandate that 
may result in expenditures of $100 million or more for State, local, 
and Tribal governments, in the aggregate, and the private sector in any 
one year. Accordingly, EPA has prepared, under section 202 of the UMRA, 
a written statement addressing the following areas:
    (1) Authorizing legislation;
    (2) cost-benefit analysis including an analysis of the extent to 
which the costs to State, local, and tribal governments will be paid 
for by the Federal government;
    (3) estimates of future compliance costs and disproportionate 
budgetary effects;
    (4) macro-economic effects; and
    (5) a summary of EPA's consultation with State, local, and tribal 
governments, a summary of their concerns, and a summary of EPA's 
evaluation of their concerns.
    A summary of this analysis follows and a more detailed description 
is presented in EPA's Regulatory Impact Analysis (RIA) of the Arsenic 
Rule (US EPA, 2000e) which is included in the docket for this proposed 
rulemaking.
    a. Authorizing legislation. Today's proposed rule is proposed 
pursuant to section 1412(b)(13) of the 1996 amendments to the SDWA 
which requires EPA to propose and promulgate a national primary 
drinking water regulation for arsenic, establishes a statutory deadline 
of January 1, 2000, to propose this rule, and establishes a statutory 
deadline of January 1, 2001, to promulgate this rule.
    b. Cost-benefit analysis. Section XIII. of this Preamble, 
describing the Regulatory Impact Analysis (RIA) and Health Risk 
Reduction and Cost Analysis (HRRCA) for arsenic, contains a detailed 
cost-benefit analysis in support of the arsenic rule. Today's proposed 
rule is expected to have a total annualized cost of approximately $379 
to 445 million.\9\ This total annualized cost includes the total annual 
administrative costs of State, local, and tribal governments, in 
aggregate, less than 1% of the cost, and total annual treatment (CWS 
only, as proposed), monitoring, reporting, and record keeping impacts 
on public water systems, in aggregate, of approximately $376.7 to 439.8 
million.\10\ Treatment costs estimates are presented in Sections IX.D. 
and E. of this Preamble, and administrative costs are discussed in 
section 9 of the RIA (US EPA, 2000e).
---------------------------------------------------------------------------

    \9\ Costed as proposed, using the 3 percent and 7 percent 
discount rate cost-of-capital values in Table X-8, in 1999 $ with 
NTNCWS monitoring and reporting, but not required to comply with the 
MCL. If NTNCWS were to comply with the MCL, their treatment costs 
would bring the annualized cost to $394.4 million.
    \10\ Source: table XII-6, in 1997 $.
---------------------------------------------------------------------------

    The RIA includes both qualitative and monetized benefits for 
improvements in health and safety. EPA estimates the proposed arsenic 
rule will have annual monetized benefits for bladder cancer of 
approximately $43.6 to 104.2 million if the MCL were to be set at 3 
g/L, $31.7 to 89.9 million if set at 5 g/L, $17.9 to 
52 million if set at 10 g/L, and $7.9 to 29.8 million if set 
at 20g/L (EPA also estimates possible lung cancer benefits 
based on the ``What If'' scenario of $47-448 million at 3 g/L, 
$35-384 million at 5 g/L, $19.6-224 million at 10 g/
L, and $8.8-128 million at 20 g/L.).\11\ The monetized health 
benefits of reducing arsenic exposures in drinking water are 
attributable to the reduced incidence of fatal and non-fatal bladder 
cancers. Under baseline assumptions (no control of arsenic exposure 50 
g/L), 10-17 fatal bladder cancers and 29-48 non-fatal bladder 
cancers per year are associated with arsenic exposures through CWSs. At 
a arsenic level of 3 g/L, an estimated 5.7 to 10.9 fatal 
bladder cancers and 22 to 42 non-fatal bladder cancers per year are 
prevented. At a level of 5 g/L, an estimated 4 to 9 fatal 
bladder cancers and 16 to 36 non-fatal bladder cancers per year are 
prevented. At a level 10 g/L, 2 to 6 fatal and 9 to 21 non-
fatal bladder cancers per year are prevented. At a level 20 g/
L, 1 to 3 fatal and 3 to 9 non-fatal bladder cancers per year are 
prevented.
---------------------------------------------------------------------------

    \11\ Source: Table X-7.

---------------------------------------------------------------------------

[[Page 38966]]

    In addition to quantifiable benefits, EPA has identified several 
potential non-quantifiable benefits associated with reducing arsenic 
exposures in drinking water. These potential benefits are difficult to 
quantify because of the uncertainty surrounding their estimation. Non-
quantifiable benefits may include any peace-of-mind benefits specific 
to reduction of arsenic risks that may not be adequately captured in 
the Value of Statistical Life (VSL) estimate.
    State, local and Tribal governments will incur a range of 
administrative costs with the MCL options in complying with the arsenic 
rule. Administrative costs associated with water mitigation can include 
costs associated with program management, inspections, and enforcement 
activities. EPA estimates the total annual costs of administrative 
activities for compliance with the MCL to be approximately $2.8 
million.
    c. Financial Assistance. Various Federal programs exist to provide 
financial assistance to State, local, and tribal governments to 
administer and comply with this and other drinking water rules. The 
Federal government provides funding to States that have a primary 
enforcement responsibility for their drinking water programs through 
the Public Water Systems Supervision (PWSS) Grants program. Additional 
funding is available from other programs administered either by EPA or 
other Federal agencies. These include the Drinking Water State 
Revolving Fund (DWSRF) and Housing and Urban Development's Community 
Development Block Grant Program. For example, the SDWA authorizes the 
Administrator of the EPA to award capitalization grants to States, 
which in turn can provide low cost loans and other types of assistance 
to eligible public water systems. The DWSRF assists public water 
systems with financing the costs of infrastructure needed to achieve or 
maintain compliance with SDWA requirements. Each State will have 
considerable flexibility to determine the design of its program and to 
direct funding toward its most pressing compliance and public health 
protection needs. States may also, on a matching basis, use up to ten 
percent of their DWSRF allotments for each fiscal year to assist in 
running the State drinking water program.
    Under PWSS Program Assistance Grants, the Administrator may make 
grants to States to carry out public water system supervision programs. 
States may use these funds to develop primacy programs. States may 
``contract'' with other State agencies to assist in the development or 
implementation of their primacy program. However, States may not use 
program assistance grant funds to contract with regulated entities 
(i.e., water systems). PWSS Grants may be used by States to set-up and 
administer a State program which includes such activities as: public 
education, testing, training, technical assistance, developing and 
administering a remediation grant and loan or incentive program 
(excludes the actual grant or loan funds), or other regulatory or non-
regulatory measures.
    d. Estimates of future compliance costs and disproportionate 
budgetary effects. To meet the requirement in section 202 of the UMRA, 
EPA analyzed future compliance costs and possible disproportionate 
budgetary effects of the MCL options. The Agency believes that the cost 
estimates, indicated previously and discussed in more detail in Section 
XIII.B of today's Preamble accurately characterize future compliance 
costs of the proposed rule.
    With regard to the disproportionate impacts, EPA considered 
available data sources in analyzing the disproportionate impacts upon 
geographic or social segments of the nation or industry. No rationale 
for disproportionate impacts by geography were identified. EPA will 
prepare a small entity compliance guide, a monitoring/analytical 
manual, and a small systems technology manual that will assist the 
public and private sector. To fully consider the potential 
disproportionate impacts of this proposed rule, this analysis also 
developed three other measures:
    (1) Reviewing the impacts on small versus large systems;
    (2) reviewing the costs to public versus private water systems; and
    (3) reviewing the household costs for the proposed rule.
    The first measure, the national impacts on small versus large 
systems, is shown in Section IX, Table IX-12, Total Annual Costs per 
Household. Small systems are defined as those systems serving 10,000 
people or less and large systems are those systems that serve more than 
10,000 people. The higher compliance costs to small systems is 
primarily due to the greater number of small systems as opposed to 
large systems (i.e., there are 39,420 small systems versus 1,443 large 
systems).
    The second measure of disproportionate impacts evaluated is the 
relative total costs to public versus private water systems, by size. 
Table XIV-2 presents the total annualized costs for public and private 
systems by system size category for the 3 g/L, 5 g/L, 
10 g/L, and 20 g/L arsenic levels. The costs are 
comparable for public and private systems across system sizes for all 
options. This pattern may be due in large part to the limited number of 
treatment options assumed to be available to either public or private 
systems to remove arsenic.

         Table XIV-2.--Average Annual Cost per CWS by Ownership
------------------------------------------------------------------------
                                   Treatment and monitoring   Total cost
                                             costs          ------------
           System size            --------------------------
                                      Public      Private    All systems
------------------------------------------------------------------------
                          MCL = 3 g/L
------------------------------------------------------------------------
100..............................       $9,475       $7,354       $7,559
101-500..........................       25,228       18,570       20,588
501-1,000........................       34,688       31,645       33,474
1,001-3,300......................       60,929       51,097       58,189
3,301-10,000.....................      135,573      111,396      131,197
10,001-1,000,000.................      578,591      547,969      573,423
>1,000,000.......................    3,885,713  ...........    3,885,713
------------------------------------------------------------------------
                          MCL = 5 g/L
------------------------------------------------------------------------
100..............................        9,720        7,212        7,450
101-500..........................       24,560       18,223       20,198

[[Page 38967]]

 
501-1,000........................       34,124       30,697       32,778
1,001-3,300......................       57,277       48,198       54,666
3,301-10,000.....................      124,552      102,005      120,399
10,001-1,000,000.................      518,647      459,930      508,640
>1,000,000.......................    2,669,474  ...........    2,669,474
------------------------------------------------------------------------
                          MCL = 10 g/L
------------------------------------------------------------------------
100..............................        9,453        7,135        7,350
101-500..........................       23,584       17,675       19,551
501-1,000........................       32,271       29,160       31,048
1,001-3,300......................       53,357       44,785       50,921
3,301-10,000.....................      113,338       91,244      109,278
10,001-1,000,000.................      458,340      415,520      450,835
>1,000,000.......................    1,395,498  ...........    1,395,498
------------------------------------------------------------------------
                          MCL = 20 g/L
------------------------------------------------------------------------
100..............................        9,121        6,950        7,157
101-500..........................       22,778       16,954       18,738
501-1,000........................       30,493       27,668       29,376
1,001-3,300......................       48,399       41,625       46,501
3,301-10,000.....................       99,872       79,128       95,983
10,001-1,000,000.................      394,742      334,737      384,868
>1,000,000.......................      921,121  ...........     921,121
------------------------------------------------------------------------
* Costs were calculated at a commercial interest rate and include system
  treatment, monitoring, and administrative costs; note that systems
  serving over 1 million people are public surface water systems.

    The third measure, household costs, can also be used to gauge the 
impact of a regulation and to determine whether there are 
disproportionately high impacts in particular segments of the 
population. A detailed analysis of household cost impacts by system 
size is presented in the RIA (US EPA 2000e). The costs for households 
served by public and private water systems are presented in Table XIV-
3. As expected, cost per household increases as system size decreases. 
Cost per household is higher for households served by smaller systems 
than larger systems for two reasons. First, smaller systems serve far 
fewer households than larger systems and, consequently, each household 
must bear a greater percentage share of the system's costs. Second, 
smaller systems tend to have higher influent arsenic concentrations 
that, on a per-capita or per-household basis, require more expensive 
treatment methods to achieve the target arsenic level.
    There is a moderate difference in annual cost per household for the 
3 g/L, 5 g/L, 10 g/L, and 20 g/L 
levels for each size category. However, the costs per household are 
higher for private systems than for public systems. For public systems, 
the cost per household ranges from $24.73 to $341.78 per year at 5 
g/L and from $22.03 to $329.17 per year at 10 g/L. 
For private systems, the ranges are $21.91 to $369.21 per year, and 
$19.06 to $363.08 per year, respectively.

                  Table XIV-3.--Average Compliance Costs per Household for CWSs Exceeding MCLs
----------------------------------------------------------------------------------------------------------------
                                                                     Groundwater              Surface water
                         System size                         ---------------------------------------------------
                                                                 Public      Private       Public      Private
----------------------------------------------------------------------------------------------------------------
                                              MCL = 3 g/L
----------------------------------------------------------------------------------------------------------------
100.........................................................      $338.44      $374.86       328.94      $385.61
101-500.....................................................       218.59       285.61       135.98       183.96
501-1,000...................................................       108.63       112.60        45.44        46.72
1,001-3,300.................................................        62.17        83.24        21.13        27.91
3,301-10,000................................................        44.67        62.96        18.34        22.94
10,001-1,000,000............................................        31.29        31.29        26.49        22.81
>1,000,000..................................................  ...........  ...........         2.70  ...........
----------------------------------------------------------------------------------------------------------------
                                              MCL = 5 g/L
----------------------------------------------------------------------------------------------------------------
100.........................................................       341.78       369.21       323.48       330.05
101-500.....................................................       213.11       280.76       135.22       182.65
501-1,000...................................................       106.00       108.40        44.86        46.35
1,001-3,300.................................................        58.31        77.54        20.07        26.57
3,301-10,000................................................        40.60        57.25        16.89        21.54
10,001-1,000,000............................................        28.12        28.63        24.73        21.91

[[Page 38968]]

 
>1,000,000..................................................  ...........  ...........         1.73  ...........
----------------------------------------------------------------------------------------------------------------
                                              MCL = 10 g/L
----------------------------------------------------------------------------------------------------------------
100.........................................................       329.17       363.09       317.80       325.64
101-500.....................................................       203.40       273.04       132.74       180.88
501-1,000...................................................        99.45       102.19        42.98        44.48
1,001-3,300.................................................        53.70        71.97        18.62        25.49
3,301-10,000................................................        36.30        50.41        14.68        18.55
10,001-1,000,000............................................        24.09        24.47        22.03        19.06
>1,000,000..................................................  ...........  ...........         0.89  ...........
----------------------------------------------------------------------------------------------------------------
                                              MCL = 20 g/L
----------------------------------------------------------------------------------------------------------------
100.........................................................       320.13       352.42       310.11       324.84
101-500.....................................................       195.99       262.01       132.68       179.93
501-1,000...................................................        93.27        96.63        42.26        44.04
1,001-3,300.................................................        48.03        66.12        18.20        24.87
3,301-10,000................................................        31.38        44.14        13.35        17.53
10,001-1,000,000............................................        20.27        20.39        19.96  ...........
>1,000,000..................................................  ...........  ...........         0.55  ...........
----------------------------------------------------------------------------------------------------------------
*Costs to households were calculated at a commercial interest rate and include system treatment, monitoring, and
  administrative costs; note that systems serving over 1 million people are public surface water systems.


  Table XIV-4.--Average Compliance Costs per Household for CWSs Exceeding MCLs as a Percent of Median Household
                                                     Income
----------------------------------------------------------------------------------------------------------------
                                                                     Groundwater              Surface water
                         System size                         ---------------------------------------------------
                                                                 Public      Private       Public      Private
----------------------------------------------------------------------------------------------------------------
                                              MCL = 3 g/L
----------------------------------------------------------------------------------------------------------------
100.........................................................         0.85         0.95         0.83         0.85
101-500.....................................................         0.55         0.72         0.34         0.46
501-1,000...................................................         0.27         0.28         0.11         0.12
1,001-3,300.................................................         0.16         0.21         0.05         0.07
3,301-10,000................................................         0.11         0.16         0.05         0.06
10,001-1,000,000............................................         0.08         0.08         0.07         0.06
>1,000,0000.................................................  ...........  ...........         0.01  ...........
----------------------------------------------------------------------------------------------------------------
                                              MCL = 5 g/L
----------------------------------------------------------------------------------------------------------------
100.........................................................         0.86         0.93         0.82         0.83
101-500.....................................................         0.54         0.71         0.34         0.46
501-1,000...................................................         0.27         0.27         0.11         0.12
1,001-3,300.................................................         0.15         0.20         0.05         0.07
3,301-10,000................................................         0.10         0.14         0.04         0.05
10,001-1,000,000............................................         0.07         0.07         0.06         0.06
>1,000,0000.................................................  ...........  ...........         0.00  ...........
----------------------------------------------------------------------------------------------------------------
                                              MCL = 10 g/L
----------------------------------------------------------------------------------------------------------------
100.........................................................         0.83         0.92         0.80         0.82
101-500.....................................................         0.51         0.69         0.33         0.46
501-1,000...................................................         0.25         0.26         0.11         0.11
1,001-3,300.................................................         0.14         0.18         0.05         0.06
3,301-10,000................................................         0.09         0.13         0.04         0.05
10,001-1,000,000............................................         0.06         0.06         0.06         0.05
>1,000,0000.................................................  ...........  ...........         0.00  ...........
----------------------------------------------------------------------------------------------------------------
                                              MCL = 20 g/L
----------------------------------------------------------------------------------------------------------------
100.........................................................         0.81         0.89         0.78         0.82
101-500.....................................................         0.49         0.66         0.33         0.45
501-1,000...................................................         0.24         0.24         0.11         0.11
1,001-3,300.................................................         0.12         0.17         0.05         0.06
3,301-10,000................................................         0.08         0.11         0.03         0.04
10,001-1,000,000............................................         0.05         0.05         0.05         0.00

[[Page 38969]]

 
>1,000,0000.................................................  ...........  ...........         0.00  ...........
----------------------------------------------------------------------------------------------------------------
* Costs to household were calculated at a commercial interest rate and include system treatment, monitoring, and
  administrative costs; median household income in May 1999 was $39,648 from the 1998 annual median household
  income from the Census.

    To further evaluate the impacts of these household costs, the costs 
per household were compared to median household income data for each 
system-size category. The result of this calculation, presented in 
Table XIV-4 for public and private systems, indicate a household's 
likely share of incremental costs in terms of its household income. For 
all system sizes, household costs as a percentage of median household 
income are less than one percent for households served by either public 
or private systems. Similar to the cost per household results on which 
they are based, household impacts exhibit little variability across 
arsenic levels.
    e. Macroeconomic effects. As required under UMRA Sec. 202, EPA is 
required to estimate the potential macro-economic effects of the 
regulation. These types of effects include those on productivity, 
economic growth, full employment, creation of productive jobs, and 
international competitiveness. Macro-economic effects tend to be 
measurable in nationwide econometric models only if the economic impact 
of the regulation reaches 0.25 percent to 0.5 percent of Gross Domestic 
Product (GDP). In 1998, real GDP was $7,552 billion so a rule would 
have to cost at least $18 billion annually to have a measurable effect. 
A regulation with a smaller aggregate effect is unlikely to have any 
measurable impact unless it is highly focused on a particular 
geographic region or economic sector. The macro-economic effects on the 
national economy from the arsenic rule should be negligible based on 
the fact that, assuming 100 percent compliance with an MCL, the total 
annual costs are approximately $756 million at the 3 g/L 
level, $445 million at the 5 g/L level, about $195 million at 
the 10 g/L level, and at the 20 g/L level, about $77 
million (at a 7 percent discount rate), and the costs are not expected 
to be highly focused on a particular geographic region or industry 
sector.
    f. Summary of EPA's consultation with State, local, and tribal 
governments and their concerns. Under UMRA section 204, EPA is to 
provide a summary of its consultation with elected representatives (or 
their designated authorized employees) of affected State, local, and 
Tribal governments in this rulemaking. EPA initiated consultations with 
governmental entities and the private sector affected by this 
rulemaking through various means. This included five stakeholder 
meetings announced in the Federal Register and open to any one 
interested in attending in person or by phone, and presentations at 
meetings of the American Water Works Association (AWWA), the 
Association of State Drinking Water Administrators (ASDWA), the 
Association of California Water Agencies (ACWA), and the Association of 
Metropolitan Water Agencies (AMWA). Participants in EPA's stakeholder 
meetings also included representatives from the National Rural Water 
Association, AMWA, ASDWA, AWWA, ACWA, Rural Community Assistance 
Program, State departments of environmental protection, State health 
departments, State drinking water programs, and a Tribe. EPA also made 
presentations at Tribal meetings in Nevada, Alaska, and California. To 
address the proposed rule's impact on small entities, the Agency 
consulted with representatives of small water systems and convened a 
Small Business Advocacy Review Panel in accordance with the Regulatory 
Flexibility Act (RFA) as amended by the Small Business Regulatory 
Enforcement Fairness Act (SBREFA). Two of the small entity 
representatives were elected officials from local governments. EPA also 
invited State drinking water program representatives to participate in 
a number of workgroup meetings. In addition to these consultations, EPA 
participated in and gave presentations at AWWA's Technical Workgroup 
for Arsenic. State public health department and drinking water program 
representatives, drinking water districts, and ASDWA participated in 
the Technical Workgroup meetings. Finally EPA presented the benefits 
analysis to State and Tribal health and environmental agencies.
    The public docket for this proposed rulemaking contains meeting 
summaries for EPA's five stakeholder meetings on arsenic in drinking 
water, written comments received by the Agency, and provides details 
about the nature of State, local, and Tribal government's concerns. A 
summary of State, local, and Tribal government concerns on this 
proposed rulemaking is in the next section.
    In order to inform and involve Tribal governments in the rulemaking 
process, EPA staff attended the 16th Annual Consumer Conference of the 
National Indian Health Board on October 6-8, 1998 in Anchorage, Alaska. 
Over nine hundred attendees representing Tribes from across the country 
were in attendance. During the conference, EPA conducted two workshops 
for meeting participants. The objectives of the workshops were to 
present an overview of EPA's drinking water program, solicit comments 
on key issues of potential interest in upcoming drinking water 
regulations, and to solicit advice in identifying an effective 
consultative process with Tribes for the future.
    EPA, in conjunction with the Inter Tribal Council of Arizona 
(ITCA), also convened a Tribal consultation meeting on February 24-25, 
1999, in Las Vegas, Nevada to discuss ways to involve Tribal 
representatives, both Tribal council members and tribal water utility 
operators, in the stakeholder process. Approximately twenty-five 
representatives from a diverse group of Tribes attended the two-day 
meeting. Meeting participants included representatives from the 
following Tribes: Cherokee Nation, Nezperce Tribe, Jicarilla Apache 
Tribe, Blackfeet Tribe, Seminole Tribe of Florida, Hopi Tribe, Cheyenne 
River Sioux Tribe, Menominee Indian Tribe, Tulalip Tribes, Mississippi 
Band of Choctaw Indians, Narragansett Indian Tribe, and Yakama Nation.
    The major meeting objectives were to:
    (1) identify key issues of concern to Tribal representatives;
    (2) solicit input on issues concerning current OGWDW regulatory 
efforts;
    (3) solicit input and information that should be included in 
support of future drinking water regulations; and

[[Page 38970]]

    (4) provide an effective format for Tribal involvement in EPA's 
regulatory development process.
    EPA staff also provided an overview on the forthcoming arsenic rule 
at the meeting. The presentation included the health concerns 
associated with arsenic, EPA's current position on arsenic in drinking 
water, the definition of an MCL, an explanation of the difference 
between point-of-use and point-of-entry treatment devices, and specific 
issues for Tribes. The following questions were posed to the Tribal 
representatives to begin discussion on arsenic in drinking water:
    (1) What are the current arsenic levels in your water systems?
    (2) What are Tribal water systems affordability issues in regard to 
arsenic?
    (3) Does your Tribe use well water, river water or lake water?
    (4) Purchase water from another drinking water utility?
    The summary for the February 24-25, 1999 meeting was sent to all 
565 Federally recognized Tribes in the United States.
    EPA also conducted a series of workshops at the Annual Conference 
of the National Tribal Environmental Council which was held on May 18-
20, 1999 in Eureka, California. Representatives from over 50 Tribes 
attended all, or part, of these sessions. The objectives of the 
workshops were to provide an overview of forthcoming EPA regulations 
affecting water systems; discuss changes to operator certification 
requirements; discuss funding for Tribal water systems; and to discuss 
innovative approaches to regulatory cost reduction. Meeting summaries 
for EPA's Tribal consultations are available in the public docket for 
this proposed rulemaking.
    g. Nature of State, local, and Tribal government concerns and how 
EPA addressed these concerns. State and local governments raised 
several concerns, including the high costs of the rule to small 
systems; the burden of revising the State primacy program; the high 
degree of uncertainty associated with the benefits; the high costs of 
including Non-Transient Non-Community Water Systems (NTNCWSs). EPA 
modified regulations governing the revision of State primacy in order 
to decrease the burden of the new arsenic regulation in response to 
State concerns that EPA minimize paperwork and documentation of 
existing programs that would manage the arsenic regulation. Section XI. 
asks for comment on alternate MCL options, based partly on the high 
costs of the rule for small systems and uncertainty associated with the 
risks.
    Tribal representatives were generally supportive of regulations 
which would ensure a high level of water quality, but raised concerns 
over funding for regulations. With regard to the forthcoming proposed 
arsenic rule, many Tribal representatives saw the health benefits as 
highly desirable, but felt that unless additional funds were made 
available, implementing the regulation would be difficult for many 
Tribes.
    EPA understands the State, local, and tribal government concerns 
with the above issues. The Agency believes the options for small 
systems, proposed for public comment in this rulemaking, will address 
stakeholder concerns pertaining to small systems and will help to 
reduce the financial burden to these systems. Small systems compliance 
technologies and associated costs were listed in section VIII.E. 
Regionalization, the process by which a small system can connect with 
another system and purchase water, is a non-treatment option that could 
be considered for small systems. The costs for regionalization by 
system size are presented as Treatment Train #1 in Table VIII-3 of 
section VIII.B. Sections XII.C address tribal SRF and grant funding.
    Non-Transient Non-Community Water Systems (NTNCWSs) are only 
required to monitor and report exceedances of the MCL. A detailed 
discussion of the exposure to arsenic in NTNCWSs is shown in section 
V.F. of this Preamble. EPA has conducted a preliminary analysis on 
exposure and risks to NTNCWSs and is soliciting public comment on this 
preliminary analysis. An analysis of the potential benefits and costs 
of arsenic in drinking water for NTNCWSs is summarized in the preamble 
and included in the docket for this proposed rulemaking (US EPA 2000e).
    The Agency is basing this regulation on the risks to the general 
population and is not excluding any particular segments of the 
population. For a more complete discussion on the risks of arsenic in 
drinking water and air, see section II.C. of this Preamble.
    h. Regulatory Alternatives Considered. As required under section 
205 of the UMRA, EPA considered several regulatory alternatives in 
developing an MCL for arsenic in drinking water. In preparation for 
this consideration, the Regulatory Impact Analysis and Health Risk 
Reduction and Cost Analysis (HRRCA) for Arsenic evaluated arsenic 
levels of 3 g/L, 5 g/L, 10 g/L, and 20 
g/L.
    The Regulatory Impact Analysis and HRRCA also evaluated national 
costs and benefits of States choosing to reduce arsenic exposure in 
drinking water. For further discussion on the regulatory alternatives 
considered in this proposed rulemaking, see section XIII. of this 
Preamble. EPA examined a range of regulatory alternatives that could be 
employed to achieve the objectives of this rule and chose what it 
believes is the least burdensome such alternative. The regulatory 
approach embodied in this rule includes a proposed MCL that relies on 
the use of the Administrator's discretionary authority under section 
1412(b)(6) of the SDWA to set a less stringent level than the feasible 
level. The exercise of these authorities in this manner is expected to 
reduce overall burden on regulated entitities (as compared to the 
burden of a more stringent level) but still maximize health risk 
reduction. (See section XI.A for a more complete discussion of the 
rationale for the exercise of these authorities.) In terms of coverage 
of the rule, we are proposing that only CWSs be fully covered by the 
rule, driven, in part by consideration of the burden associated with 
not covering NTNCWSs in view of the minimal health risk reduction that 
would be achieved. The proposed approach is also based upon an analysis 
and listing of least cost treatment alternatives (including use of 
point of use treatment devices) that are collectively expected to 
reduce regulatory burden. Finally, today's proposal includes an 
approach to monitoring and reporting that involves a framework that 
provides for reduced regulatory burden where arsenic levels are low. 
Also, see EPA's Regulatory Impact Analysis for Arsenic (US EPA 2000e).
2. Impacts on Small Governments
    In developing this rule, EPA consulted with small governments 
pursuant to section 203 of the UMRA to address impacts of regulatory 
requirements in the rule that might significantly or uniquely affect 
small governments. In preparation for the proposed arsenic rule, EPA 
conducted analysis on small government impacts and included small 
government officials or their designated representatives in the rule 
making process. EPA conducted stakeholder meetings on the development 
of the arsenic rule which gave a variety of stakeholders, including 
small governments, the opportunity for timely and meaningful 
participation in the regulatory development process. Groups such as the 
National Association of Towns and Townships, the National League of 
Cities, and the National Association of Counties participated in the 
proposed rulemaking process.

[[Page 38971]]

Through such participation and exchange, EPA notified potentially 
affected small governments of requirements under consideration and 
provided officials of affected small governments with an opportunity to 
have meaningful and timely input into the development of the regulatory 
proposal. See section XIV.B.6.a. for a summary of the Small Business 
Review Panel consultations.
    In addition, EPA will educate, inform, and advise small systems, 
including those run by small governments, about the arsenic rule 
requirements. One of the most important components of this process is 
the Small Entity Compliance Guide, required by the Small Business 
Regulatory Enforcement Fairness Act of 1996 shortly after the rule is 
promulgated. This plain-English guide will explain what actions a small 
entity must take to comply with the rule. Also, the Agency is 
developing fact sheets that concisely describe various aspects and 
requirements of the arsenic rule.

D. Paperwork Reduction Act (PRA)

    The information collection requirements in this proposed rule have 
been submitted for approval to the Office of Management and Budget 
(OMB) under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. An 
Information Collection Request (ICR) document has been prepared by EPA 
(ICR, No. 1948.01) and a copy may be obtained from Sandy Farmer by mail 
at Collection Strategies Division; U.S. Environmental Protection Agency 
(2822); 1200 Pennsylvania Ave., NW, Washington, DC 20460, by email at 
[email protected], or by calling (202) 260-2740. A copy may 
also be downloaded off the Internet at http://www.epa.gov/icr.
    Two types of information will be collected under the proposed 
arsenic rule. First, information on CWSs and NTNCWSs and their arsenic 
levels reported under 50 g/L will enable the States and EPA to 
evaluate compliance with the lower MCL. This information, most of which 
consists of monitoring results, corresponds to arsenic information 
already collected from water systems. Arsenic monitoring and reporting 
will continue annually for surface water systems or once every three 
years for ground water systems, unless the MCL is exceeded or a State 
grants a waiver (see section VII). Other existing information and 
reporting requirements, such as Consumer Confidence Reports (US EPA, 
1998j) and the public notification requirements (US EPA, 2000c), will 
be amended to reflect the lower MCL for arsenic. As proposed, NTNCWSs 
will not be required to comply with the MCL because of the low exposure 
levels as explained in section XI.C. However, EPA is requiring NTNCWSs 
to report to the State and public when it exceeds the MCL through 
public notification requirements. As is the case for other 
contaminants, required information on system arsenic levels must be 
provided by affected systems and is not considered to be confidential. 
EPA believes the information needs discussed previously, on compliance 
with the MCL programs, are essential to achieving the arsenic-related 
health risk reductions anticipated by EPA under the proposed rule.
    EPA has estimated the burden associated with the specific record 
keeping and reporting requirements of the proposed rule in an 
accompanying Information Collection Request (ICR), which is available 
in the public docket for this proposed rulemaking. Burden means the 
total time, effort, or financial resources expended by persons to 
generate, maintain, retain, or disclose or provide information to or 
for a Federal agency. This includes the time needed to review 
instructions; develop, acquire, install, and utilize technology and 
systems for the purposes of collecting, validating, and verifying 
information, processing and maintaining information, and disclosing and 
providing information; adjust the existing procedures to comply with 
any previously applicable instructions and requirements; train 
personnel to be able to respond to a collection of information; search 
data sources; complete and review the collection of information; and 
transmit or otherwise disclose the information.
    The ICR for the proposed rule covers the information collection, 
reporting and record-keeping requirements for the three-year period 
following promulgation of the Arsenic Rule. There are several 
activities that PWSs must perform in preparation for compliance with 
the revised Arsenic Rule in the first three years. Start-up activities 
include reading the final rule to become familiar with the requirements 
and training staff to perform the required activities. The number of 
hours required to perform each activity varies by system size. The 
total start-up burden per system for systems serving less than 10,000 
people is estimated to be 24 hours; the total start-up burden per 
system for systems serving more than 10,000 people is estimated to be 
40 hours. The total hour burden for the 74,607 PWSs (including NTNCWS) 
covered by this rule is estimated to be 1,847,784 hours, or an annual 
average of 615,928 hours. There are no monitoring, record-keeping, 
reporting or equipment costs for PWSs during the first three-year 
period. EPA expects States to incur only nominal information 
collection, reporting or record-keeping costs during the first three 
years. (For estimates of the cost of information collection, reporting 
and record-keeping over a 20-year period, see ICR No. 1948.01)
    An agency may not conduct or sponsor, and a person is not required 
to respond to, a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for EPA's 
regulations are listed in 40 CFR part 9 and 48 CFR Chapter 15.
    Comments are requested on the Agency's need for this information, 
the accuracy of the provided burden estimates, and any suggested 
methods for minimizing respondent burden, including through the use of 
automated collection techniques. Send comments on the ICR to the 
Director, Collection Strategies Division; U.S. Environmental Protection 
Agency (2822); 1200 Pennsylvania Ave., NW, Washington, DC 20460; and to 
the Office of Information and Regulatory Affairs, Office of Management 
and Budget, 725 17th St., NW, Washington, DC 20503, marked ``Attention: 
Desk Officer for EPA.'' Include the ICR number in any correspondence. 
Since OMB is required to make a decision concerning the ICR between 30 
and 60 days after June 22, 2000, a comment to OMB is best assured of 
having its full effect if OMB receives it by July 24, 2000. The final 
rule will respond to any OMB or public comments on the information 
collection requirements contained in this proposal.

E. National Technology Transfer and Advancement Act (NTTAA)

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (NTTAA), (Public Law 104-113, section 12(d), 15 U.S.C. 272 
note), directs EPA to use voluntary consensus standards in its 
regulatory activities unless to do so would be inconsistent with 
applicable law or otherwise impractical. Voluntary consensus standards 
are technical standards (e.g., material specifications, test methods, 
sampling procedures, business practices, etc.) that are developed or 
adopted by voluntary consensus standard bodies. The NTTAA directs EPA 
to provide to Congress, through OMB, explanations when the Agency 
decides not to use available and applicable voluntary consensus 
standards.
    EPA's process for selecting analytical methods is consistent with 
section 12(d) of the NTTAA. EPA performed a

[[Page 38972]]

literature search to identify analytical methods from industry, 
academia, voluntary consensus standard bodies and other parties that 
could be used to reliably measure total arsenic in drinking water at 
the proposed MCL of 0.005 mg/L. Today's proposed rulemaking allows the 
use of analytical methods which are described in the ``Annual Book of 
ASTM Standards'' (American Society for Testing and Materials, 1994 and 
1996) and in ``Standards for the Examination of Water and Wastewater'' 
(APHA, 1992 and 1995). The four methods published by these consensus 
organizations include SM 3113B, SM 3114B, ASTM 2972-93B and ASTM 2972-
93C. These methods were all approved for arsenic analysis in previous 
methods-related rulemakings for the MCL of 0.050
mg/L. Along with the review of other analytical methods, EPA also re-
evaluated these consensus methods for the new arsenic standard. The 
Agency believes these methods will still be reliable for compliance 
monitoring at the proposed MCL of 0.005 mg/L. Additional information on 
these methods are shown in section VI. C. and F. of today's preamble. 
One consensus method, SM 3120B, will be withdrawn in today's 
rulemaking. As discussed in section VI.D., SM 3120B will be withdrawn 
because the detection limit for this method is inadequate to reliably 
determine the presence of arsenic at the proposed MCL of 0.005 mg/L.
    Although no other methods were identified from the literature 
search, EPA welcomes comments on this aspect of today's proposed 
rulemaking and specifically invites the public to identify potentially-
applicable voluntary consensus standards, explain why such standard 
should be considered for inclusion with this regulation, and to provide 
the necessary information from inter-laboratory studies on detection 
limits, accuracy, recovery and precision.

F. Executive Order 12898: Environmental Justice

    Executive Order 12898 ``Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations,'' (59 FR 
7629, February 16, 1994) establishes a Federal policy for incorporating 
environmental justice into Federal agency missions by directing 
agencies to identify and address disproportionately high and adverse 
human health or environmental effects of its programs, policies, and 
activities on minority and low-income populations. The Agency has 
considered environmental justice-related issues concerning the 
potential impacts of this action and has consulted with minority and 
low-income stakeholders by convening a stakeholder meeting via video 
conference specifically to address environmental justice issues.
    As part of EPA's responsibilities to comply with Executive Order 
12898, the Agency held a stakeholder meeting via video conference on 
March 12, 1998, to highlight components of pending drinking water 
regulations and how they may impact sensitive sub-populations, minority 
populations, and low-income populations. Topics discussed included 
treatment techniques, costs and benefits, data quality, health effects, 
and the regulatory process. Participants included national, State, 
tribal, municipal, and individual stakeholders. EPA conducted the 
meeting by video conference call between eleven cities. This meeting 
was a continuation of stakeholder meetings that started in 1995 to 
obtain input on the Agency's Drinking Water programs. The major 
objectives for the 1998 meeting were:
    (1) Solicit ideas from Environmental Justice (EJ) stakeholders on 
known issues concerning current drinking water regulatory efforts;
    (2) Identify key issues of concern to EJ stakeholders; and
    (3) Receive suggestions from EJ stakeholders concerning ways to 
increase representation of EJ communities in OGWDW regulatory efforts.
    In addition, EPA developed a plain-English guide specifically for 
this meeting to assist stakeholders in understanding the multiple and 
sometimes complex issues surrounding drinking water regulations. A 
meeting summary for the March 12, 1998 Environmental Justice 
stakeholders meeting (US EPA, 1998b) is available in the public docket 
for this proposed rulemaking.
    During the presentation of separate cities' discussions, several 
arsenic issues came up. In Region 6 one stakeholder thought that test 
results for arsenic (discussed in ppb and g/L) were hard to 
understand, and the health effects appear to be complicated. Region 6 
participants had concerns about the toxic effects on mothers, 
individuals with different metabolisms, and individuals with poor 
nutrition. One of the stakeholders expressed a concern that the 
government was not protecting poorer communities against pollution. In 
Region 7, one stakeholder lives in an area that purchases water which 
has to be monitored. The area has a shrinking population that is 
increasing in age and immune conditions. Although there are pesticides 
in the water and air, it would not be economically practical to 
consolidate to a regional drinking water system. One member of an 
Indian tribe said Tribes tend to have more diabetes than the rest of 
the country, and diabetes seemed to be linked to arsenic exposure. In 
Region 8 a stakeholder wanted affordable or equally protective 
treatment options. A Region 8 participant asked for disclosure of 
environmental contamination. Region 9 reported some individual 
monitoring difficulties. Stakeholders wanted better access to funding 
sources. Stakeholders in Region 9 had concerns about the immuno-
compromised, young children, and pregnant women. Some stakeholders 
wanted standard setting to address regional needs, include local 
governments in the standard setting, more technical assistance and 
training, and more stakeholder involvement. Tribes and large cities 
with low income families may be burdened with more of the risk.
    The Agency considered equity-related issues concerning the 
potential impacts of this action. There is no factual basis to indicate 
that minority and low income communities are more (or less) exposed to 
arsenic in drinking water. The occurrence information suggests there is 
no difference between the percent of systems likely to be impacted in 
small communities versus larger ones. Further, arsenic in drinking 
water is primarily natural in origin (rather than related to 
contamination events) and a systematic bias based on socioeconomic 
factors would not be expected to occur. A key issue of concern is the 
potential for an uneven distribution of risk reduction benefits across 
water systems and society.
    The public is invited to comment on EPA's analysis of environmental 
justice and, specifically, to recommend additional methods to address 
environmental justice concerns with the approach for treating arsenic 
in drinking water.

G. Executive Order 13045: Protection of Children from Environmental 
Health Risks and Safety Risks

    Executive Order 13045, ``Protection of Children from Environmental 
Health Risks and Safety Risks,'' (62 FR 19885 April 23, 1997) applies 
to any rule that: (1) is determined to be ``economically significant'' 
as defined under Executive Order 12866, and (2) concerns an 
environmental health or safety risk that EPA has reason to believe may 
have a disproportionate effect on children. If the regulatory action 
meets both criteria, the Agency must evaluate the environmental health 
or safety effects of the planned rule on children, and

[[Page 38973]]

explain why the planned regulation is preferable to other potentially 
effective and reasonably feasible alternatives considered by the 
Agency.
    This proposed rule is not subject to the Executive Order because 
the Agency does not have reason to believe the environmental health 
risks or safety risks addressed by this action present a 
disproportionate risk to children. Nonetheless, we have evaluated the 
environmental health or safety effects of arsenic in drinking water on 
children. The results of this evaluation are contained in section 
III.F.5. of this Preamble. Copies of the documents used to evaluate the 
environmental health or safety effects of arsenic in drinking water on 
children have been placed in the public docket for this proposed 
rulemaking.
    The public is invited to submit or identify peer-reviewed studies 
and data, of which EPA may not be aware, that assessed results of early 
life exposure to arsenic via ingestion.

H. Executive Order 13132: Federalism

    Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August 
10, 1999), requires EPA to develop an accountable process to ensure 
``meaningful and timely input by State and local officials in the 
development of regulatory policies that have federalism implications.'' 
``Policies that have federalism implications'' is defined in the 
Executive Order to include regulations that have ``substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government.''
    Under section 6 of Executive Order 13132, EPA may not issue a 
regulation that has federalism implications, that imposes substantial 
direct compliance costs, and that is not required by statute, unless 
the Federal government provides the funds necessary to pay the direct 
compliance costs incurred by State and local governments, or EPA 
consults with State and local officials early in the process of 
developing the proposed regulation. EPA also may not issue a regulation 
that has federalism implications and that preempts State law, unless 
the Agency consults with State and local officials early in the process 
of developing the proposed regulation.
    If EPA complies by consulting, Executive Order 13132 requires EPA 
to provide to the Office of Management and Budget (OMB), in a 
separately identified section of the preamble to the rule, a federalism 
summary impact statement (FSIS). The FSIS must include a description of 
the extent of EPA's prior consultation with State and local officials, 
a summary of the nature of their concerns and the agency's position 
supporting the need to issue the regulation, and a statement of the 
extent to which the concerns of State and local officials have been 
met. Also, when EPA transmits a draft final rule with federalism 
implications to OMB for review pursuant to Executive Order 12866, EPA 
must include a certification from the agency's Federalism Official 
stating that EPA has met the requirements of Executive Order 13132 in a 
meaningful and timely manner.
    EPA has concluded that this proposed rule will have federalism 
implications. This rule will impose substantial direct compliance costs 
on State and local governments, and the Federal government will not 
provide the funds necessary to pay those costs. Accordingly, EPA 
provides the following FSIS as required by section 6(b) of Executive 
Order 13132.
    EPA consulted with State and local officials early in the process 
of developing the proposed regulation to permit them to have meaningful 
and timely input into its development. Summaries of the meetings have 
been included int public record for this proposed rulemaking. EPA 
consulted extensively with State, local, and tribal governments. For 
example, we held four public stakeholder meetings in Washington, D.C. 
(two meetings); San Antonio, Texas; and Monterey, California. 
Invitations to stakeholder meetings were extended to the National 
Association of Counties, The National Governors' Association, the 
National Association of Towns and Townships, the National League of 
Cities, and the National Conference of State Legislators. In addition, 
several elected officials were part of the Small Business Advocacy 
Review Panel convened by EPA (as required by section 609(b) of the 
Regulatory Flexibility Act). Consultation has not ended, however, but 
will be an on-going transactional process. EPA officials presented a 
summary of the rule to the National Governor's Association in a meeting 
on May 24, 2000. In addition, we scheduled a one-day stakeholders' 
meeting for the trade associations that represent elected officials on 
May 30, 2000 to discuss and solicit comment on this and other upcoming 
contaminant rules. EPA will continue to seek input from its State and 
local government partners.
    Several key issues were raised by stakeholders regarding the 
arsenic rule provision, many of which were related to reducing burden 
and maintaining flexibility. The Office of Water was able to reduce 
burden and increase flexibility in a number of areas in response to 
these comments. More specifically, elected officials expressed overall 
concerns about: (1) Factors considered in setting of the MCL and (2) 
the treatment technologies, their associated costs and waste disposal 
costs. Specific issues regarding the setting of the MCL included:
     The treatment costs associated with a lower drinking water 
standard;
     Concerns about affordability for lower income areas;
     Asking the Agency to delay setting a standard below 25 
g/L until the development of affordable technologies; and
     A lack of evidence for health effects data below 50 
g/L.
    Specific concerns regarding the treatment technologies, their 
associated costs and waste disposal costs included:
     The difficulty of using oxidation/filtration for arsenic 
removal when concentrations are 25 g/L (even after the 
addition of iron salts and pH adjustment);
     The waste disposal costs created from the use of ion 
exchange;
     The more intensive need for operator oversight and the 
amount of sludge generated using coagulation filtration and lime 
softening at a high pH;
     The difficulty in finding and the expense associated with 
activated alumina;
     The expense associated with reverse osmosis, nano-
filtration and pre-oxidation.
    The Agency responded to these concerns in several ways. We are very 
sensitive to the potential costs of treatment for a lower drinking 
water standard and have examined an array of treatment options 
(especially those that are most appropriate for small systems) in order 
to identify the least cost, affordable options that systems may use to 
comply with a new standard. We therefore do not believe that it is 
necessary to delay promulgating a rule with an MCL below 25 g/
L pending identification of such technologies, as one of the comments 
suggests. We have also included higher MCL options than the proposed 
MCL in the preamble for comment, due in large part to concerns 
expressed by elected officials and other stakeholders about the 
treatment costs associated with a low MCL. These issues are discussed 
in more detail in the sections VIII. (treatment) and XI. (regarding 
choice of the MCL). We also share the concerns of elected officials in 
connection with the affordability of a new rule for lower income areas 
and

[[Page 38974]]

have identified special programs and avenues that may be pursued to 
provide relief for such areas (see section VIII.C.).
    In response to the comment that there is a lack of evidence for 
health effects below 50 g/L, we note that the National Academy 
of Sciences'' National Research Council has categorically determined, 
based on their review of the most recent data and information 
concerning the health effects of arsenic, that the current standard of 
50 g/L is not protective and should be revised downward as 
soon as possible (NRC, 1999). This topic is discussed in more detail in 
section III.
    In response to concerns about specific treatment technologies, 
their associated costs and waste disposal costs, EPA identifies several 
treatment technologies in section VIII. Section VIII. A. identifies the 
BATs for arsenic removal and section VIII.B. identifies technologies 
which are considered affordable. The Agency agrees with the statement 
that oxidation/filtration is not an appropriate technology to treat 
arsenic to low levels. For this reason, it is not considered a BAT. The 
Agency also agrees that wastes are created using ion exchange. Section 
VIII. addresses the use of brine recycling in reducing wastes and waste 
disposal costs. In addition, regionalization or finding a new water 
source (section VIII.) are alternative non-treatment options to 
consider to avoid treatment and the costs and disposal issues 
associated with treatment. The Agency agrees with the concern that 
coagulation/filtration is more operator intensive but this technology 
and pH modifications are only considered if this treatment process is 
already in place. In regards to the amount of sludge produced, the 
additional amount of sludge generated due to the removal of arsenic is 
minor. The Agency disagrees that activated alumina is expensive and 
difficult to find. As shown in Table VIII-3, activated alumina is one 
of the cheaper treatment technologies. The Agency agrees that reverse 
osmosis, nano-filtration and the need for pre-oxidation are expensive 
treatment options. In these cases, a PWS should consider one of the 
more affordable treatment options shown in section VIII.B.

I. Executive Order 13084: Consultation and Coordination with Indian 
Tribal Governments

    Under Executive Order 13084, ``Consultation and Coordination with 
Indian Tribal Governments,'' 63 FR 27655 (May 19, 1998) EPA may not 
issue a regulation that is not required by statute, that significantly 
or uniquely affects the communities of Indian Tribal governments, and 
that imposes substantial direct compliance costs on those communities, 
unless the Federal government provides the funds necessary to pay the 
direct compliance costs incurred by the Tribal governments, or EPA 
consults with those governments. If EPA complies by consulting, 
Executive Order 13084 requires EPA to provide the Office of Management 
and Budget, in a separately identified section of the preamble to the 
rule, a description of the extent of EPA's prior consultation with 
representatives of affected Tribal governments, a summary of the nature 
of their concerns, and a statement supporting the need to issue the 
regulation. In addition, Executive Order 13084 requires EPA to develop 
an effective process permitting elected officials and other 
representatives of Indian Tribal governments ``to provide meaningful 
and timely input in the development of regulatory policies on matters 
that significantly or uniquely affect their communities.''
    EPA has concluded that this rule may significantly affect 
communities of Indian Tribal governments. It will also impose 
substantial direct compliance costs on such communities, and the 
Federal government will not provide the funds necessary to pay the 
direct costs incurred by the Tribal governments in complying with the 
rule. In developing this rule, EPA consulted with representatives of 
Tribal governments pursuant to Executive Order 13084. Summaries of the 
meetings have been included in the public docket for this proposed 
rulemaking. EPA's consultation, the nature of the governments' 
concerns, and EPA's position supporting the need for this rule are 
discussed in sections XIV.C.1.f. and g. of this Preamble.

J. Request for Comments on Use of Plain Language

    Executive Order 12866 and the President's memorandum of June 1, 
1998, require each agency to write all rules in plain language. We 
invite your comments on how to make this proposed rule easier to 
understand. For example:
     Have we organized the material to suit your needs?
     Are the requirements in the rule clearly stated?
     Does the rule contain technical language or jargon that 
isn't clear?
     Would a different format (grouping and order of sections, 
use of headings, paragraphing) make the rule easier to understand?
     Would more (but shorter) sections be better?
     Could we improve clarity by adding tables, lists, or 
diagrams?
     What else could we do to make the rule easier to 
understand?

XV. References

    The following references are referred to in this notice and are 
included in the public docket together with other correspondence and 
information. The public docket is available as described at the 
beginning of this notice. All public comments received on the proposal 
are included in the public docket.

Agency for Toxic Substances and Disease Registry. 1998. Draft 
Toxicological Profile for Arsenic. Prepared for the US Department of 
Health and Human Services by the Research Triangle Institute.
Albores, A., M. E. Cebrian, I. Tellez and B. Valdez. 1979. 
Comparative Study of Chronic Hydroarsenicism in Two Rural 
Communities in the Region Lagunra of Mexico. [in Spanish]. Bol. 
Oficina Sanit. Panam. 86:196-205.
Amy, G.L., M. Edwards, M. Benjamin, K. Carlson, J. Chwirka, P. 
Brandhuber, L. McNeill and F. Vagliasindi. 1999. Arsenic 
Treatability Options and Evaluation of Residuals Management Issues, 
Draft AWWARF Report.
Anderson, L. and K.W. Bruland. 1991. Biogeochemistry of Arsenic in 
Natural Waters: The Importance of Methylated Species. Environmental 
Science Technology. 25(3):420-427.
American Public Health Association (APHA). 1992 and 1995. Standard 
Methods for the Examination of Water and Wastewater. 18th Edition, 
American Public Health Association, 1015 Fifteenth Street N.W., 
Washington, DC 20005.
American Society for Testing and Materials (ASTM). 1994 and 1996. 
Annual Book of ASTM Standards. Vol. 11.01 and 11.02, American 
Society for Testing and Materials, 1916 Race Street, Philadelphia, 
PA 19103.
Aschbacher, P.W. and V.J. Feil. 1991. Fate of [\14\ C] Arsanilic 
Acid in Pigs and Chickens. Journal of Agriculture and Food 
Chemsitry. 38:146-148.
AWWA Research Foundation, AWWA Water Industry Technical Action Fund 
& Association of California Water Agencies. 1995. Research Needs 
Report: Arsenic in Drinking Water: Report from International Expert 
Workshop, Ellicott City, Maryland, May 31-June 2, 1995. Prepared by 
T. David Chen, HDR Engineering, Inc. August 1995.
Azcue, J. M. and J. O. Nriagu. 1994. Arsenic: Historical 
Perspectives. In Arsenic in the Environment. Part I: Cycling and 
Characterization. Nriagu, J. O., Ed. New York, NY, John Wiley and 
Sons, Inc: pp. 1-16.
Borzsonyi, M., A. Berecsky, P. Rudnai, M. Csanady and A. Horvath. 
1992. Epidemiological Studies on Human Subjects Exposed to Arsenic 
in Drinking Water in Southeast Hungary. Archives of Toxicology. 
66:77-78.

[[Page 38975]]

Buchanan, W. D. 1962. Toxicity of Arsenic Compounds. Amsterdam, 
Elsevier Scientific Publishers. pp v-viii.
Calvert, C.C. 1975. Arsenicals in Animal Feeds and Waste. In 
Arsenical Pesticides. Woolson, E. A., Ed. Washington, DC, American 
Chemical Society: pp. 70-80.
Cebrian, M. 1987. Some Potential Problems in Assessing the Effects 
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Environmental and Occupational Exposure. Archives of Toxicology. 
47:145-154.

List of Subjects

40 CFR Part 141

    Environmental protection, Chemicals, Indians--lands, 
Intergovernmental relations, Reporting and recordkeeping requirements, 
Water supply.

40 CFR Part 142

    Environmental protection, Administrative practice and procedure, 
Chemicals, Indians--lands, Reporting and recordkeeping requirements, 
Water supply.

    Dated: May 24, 2000.
Carol M. Browner,
Administrator.

    For reasons set out in the preamble, the Environmental Protection 
Agency proposes to amend 40 CFR parts 141 and 142 as follows:

PART 141--NATIONAL PRIMARY DRINKING WATER REGULATIONS

    1. The authority citation for part 141 continues to read as 
follows:

    Authority: 42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-
5, 300g-6, 300j-4, 300j-9, and 300j-11.

Subpart A--General


Sec. 141.2  [Amended]

    2. Section 141.2 is amended by revising the definition heading for 
``Point-of-entry treatment device'' to read ``Point-of-entry treatment 
device (POE)'' and revising the definition heading for ``Point-of-use 
treatment device'' to read ``Point-of-use treatment device (POU)''.
    3. Section 141.6 is amended by:
    a. In paragraph (a) by revising the reference ``(a) through (i)'' 
to read ``(a) through (k)''.
    b. Revising paragraph (c).
    c. Adding paragraphs (j) and (k).
    The revisions and additions read as follows:


Sec. 141.6  Effective dates.

* * * * *
    (c) The regulations set forth in Secs. 141.11(d); 141.21(a), (c) 
and (i); 141.22(a) and (e); 141.23(a)(3) and (a)(4); 141.23(f); 
141.24(e) and (f); 141.25(e); 141.27(a); 141.28(a) and (b); 141.31(a), 
(d) and (e); 141.32(b)(3); and 141.32(d) shall take effect immediately 
upon promulgation.
* * * * *
    (j) The arsenic MCL listed in Sec. 141.62 is effective [THREE YEARS 
AFTER PUBLICATION DATE OF THE FINAL RULE]. Compliance with the arsenic 
MCL listed in Sec. 141.62 is required for community water systems 
serving 10,000 people or less on [DATE 5 YEARS AFTER PUBLICATION DATE 
OF THE FINAL RULE], and for all other community water systems on [DATE 
3 YEARS AFTER PUBLICATION DATE OF THE FINAL RULE] for 
Secs. 141.23(a)(4), (a)(4)(i), (a)(5), (c), (f)(1), (g), (i), (k)(1), 
(k)(2), and (k)(3)(ii); 141.62(b)(16) and (c); 141.203, and revisions 
to arsenic in Appendices A and B of Subpart Q of this part for the 
public notification rule. However, the reporting date for the arsenic 
MCL listed in Appendix A of Subpart O of this part of the consumer 
confidence rule requirements and the arsenic reporting requirements in 
Sec. 141.154(b) are [THIRTY DAYS AFTER PUBLICATION DATE OF THE FINAL 
RULE]. Non-transient non-community water systems will be subject to the 
sampling, monitoring, and reporting requirements of Secs. 141.23(a), 
141.23(c)(1)-(6), 141.23(f), 141.23(g), 141.23(k), 141.203, and 141.209 
for arsenic exceeding the MCL listed in Sec. 141.62 [DATE 3 YEARS AFTER 
PUBLICATION DATE OF THE FINAL RULE].
    (k) Compliance with Secs. 141.23(c)(9), 141.24(f)(15)(ii), 
141.24(f)(22) and 141.24(h)(20) regulations for inorganics and organics 
other than total trihalomethanes and sampling frequencies for new 
systems and new sources of water is required on [DATE 3 YEARS AFTER 
PUBLICATION DATE OF THE FINAL RULE].

Subpart B--[Amended]

    4. Section 141.11 is amended by revising the second sentence of 
paragraph (a) and revising paragraph (b) to read as follows:


Sec. 141.11  Maximum contaminant levels for inorganic chemicals.

    (a) * * * The analyses and determination of compliance with the 
0.05 milligrams per liter maximum contaminant level for arsenic use the 
requirements of Sec. 141.23(l).
    (b) The maximum contaminant level for arsenic is 0.05 milligrams 
per liter for community water systems serving 10,000 people or less 
until [DATE 5 YEARS AFTER PUBLICATION DATE OF THE FINAL RULE], and for 
all other community water systems until [DATE 3 YEARS AFTER PUBLICATION 
DATE OF THE FINAL RULE]. Non-transient non-community water systems will 
be subject to sampling, monitoring and reporting requirements for 
arsenic as of [DATE 3 YEARS AFTER PUBLICATION DATE OF THE FINAL RULE]; 
however, they will not be subject to Secs. 141.23(c)(7) and (8) and 
141.62(b)(16).
* * * * *

Subpart C--[Amended]

    5. Section 141.23 is amended by:
    a. Adding a new entry for ``Arsenic'' in alphabetical order to the 
table in paragraph (a)(4)(i) and footnotes 6 and 7.
    b. Adding ``arsenic,'' before ``barium,'' in paragraph (a)(5).
    c. Adding ``arsenic,'' before ``barium,'' in paragraph (c) 
introductory text.
    d. Adding paragraph (c)(9).
    e. Revising the words ``asbestos, antimony,'' to read ``antimony, 
arsenic, asbestos,'' in paragraph (f)(1).
    f. Adding ``arsenic,'' before ``asbestos,'' in paragraph (i)(1).
    g. Adding one sentence at the end of paragraph (i)(1).
    h. Revising paragraph (i)(2).
    i. Add paragraph (i)(5).
    j. Revise ``arsenic'' entry in the table in paragraph (k)(1).
    k. Adding ``arsenic,'' before ``asbestos,'' in paragraph (k)(2) 
introductory text.
    l. In the table to paragraph (k)(2) by adding in alphabetical order 
a new entry for ``Arsenic''.
    m. Adding ``arsenic,'' before ``asbestos,'' in paragraph (k)(3) 
introductory text.
    n. Adding in alphabetical order a new entry for ``Arsenic'' to the 
table in paragraph (k)(3)(ii).
    The revisions and additions read as follows:


Sec. 141.23  Inorganic chemical sampling and analytical requirements.

    (a) * * *
    (4) * * *
    (i) * * *

[[Page 38979]]



                                   Detection Limits for Inorganic Contaminants
----------------------------------------------------------------------------------------------------------------
                                                                                                      Detection
                  Contaminant                    MCL (mg/l)                Methodology                Limit (mg/
                                                                                                          l)
----------------------------------------------------------------------------------------------------------------
 
*                  *                  *                  *                  *                  *
                                                        *
Arsenic.......................................        0.005  Atomic Absorption; Furnace............        0.001
                                                             Atomic Absorption; Platform-Stabilized   \6\ 0.0005
                                                              Temperature.
                                                             Atomic Absorption; Gaseous Hydride....        0.001
                                                             ICP-Mass Spectrometry.................   \7\ 0.0014
 
*                  *                  *                  *                  *                  *
                                                        *
----------------------------------------------------------------------------------------------------------------
*                  *                  *                  *                  *                  *
   *
\6\ The MDL reported for EPA Method 200.9 (Atomic Absorption; Platform--Stabilized Temperature) was determined
  using a 2x concentration step during sample digestion. The MDL determined for samples analyzed using direct
  analysis (i.e., no sample digestion) will be higher. Using multiple depositions, EPA 200.9 is capable of
  obtaining a MDL of 0.0001 mg/L.
\7\ Using selective ion monitoring, EPA Method 200.8 (ICP-MS) is capable of obtaining a MDL of 0.0001 mg/L.

* * * * *
    (c) * * *
    (9) All new systems or systems that use a new source of water that 
begin operation after [EFFECTIVE DATE OF THE FINAL RULE] must 
demonstrate compliance with the MCL within a period of time specified 
by the State. The system must also comply with the initial sampling 
frequencies specified by the State to ensure a system can demonstrate 
compliance with the MCL. Routine and increased monitoring frequencies 
shall be conducted in accordance with the requirements in this section.
* * * * *
    (i) * * *
    (1) * * * If a system fails to collect the required number of 
samples, compliance (average concentration) will be based on the total 
number of samples collected.
    (2) For systems which are monitoring annually, or less frequently, 
the system is out of compliance with the maximum contaminant levels for 
antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, 
cyanide, fluoride, mercury, nickel, selenium or thallium if the level 
of a contaminant is greater than the MCL. If confirmation samples are 
required by the State, the determination of compliance will be based on 
the annual average of the initial MCL exceedance and any State-required 
confirmation samples. If a system fails to collect the required number 
of samples, compliance (average concentration) will be based on the 
total number of samples collected.
* * * * *
    (5) Arsenic sampling results will be reported to the nearest 0.001 
mg/L.
* * * * *
    (k) * * *
    (1) * * *

----------------------------------------------------------------------------------------------------------------
  Contaminant and methodology \13\      EPA           ASTM \3\               SM \4\                 Other
----------------------------------------------------------------------------------------------------------------
 
*                  *                  *                  *                  *                  *
                                                        *
Arsenic \14\:
    ICP--Mass Spectrometry.........  \2\ 200.8
    Atomic Absorption; Platform....  \2\ 200.9
    Atomic Absorption; Furnace.....  .........  D-2972-93C..........  3113B...............
    Hydride Atomic Absorption......  .........  D-2972-93B..........  3114B...............
 
 *                  *                  *                  *                  *                  *
                                                         *
----------------------------------------------------------------------------------------------------------------
\2\ ``Methods for the Determination of Metals in Environmental Samples--Supplement I'', EPA/600/R-94/111, May
  1994. Available at NTIS, PB95-125472.
\3\ Annual Book of ASTM Standards,1994 and 1996, Vols. 11.01 and 11.02, American Society for Testing and
  Materials. The previous versions of D1688-95A, D1688-95C (copper), D3559-95D (lead), D1293-95 (pH), D1125-91A
  (conductivity) and D859-94 (silica) are also approved. These previous versions D1688-90A, C; D3559-90D, D1293-
  84, D1125-91A and D859-88, respectively are located in the Annual Book of ASTM Standards,1994, Vols. 11.01.
  Copies may be obtained from the American Society for Testing and Materials, 100 Barr Harbor Drive, West
  Conshohocken, PA 19428.
\4\ 18th and 19th editions of Standard Methods for the Examination of Water and Wastewater,1992 and 1995,
  respectively, American Public Health Association; either edition may be used. Copies may be obtained from the
  American Public Health Association, 1015 Fifteenth Street NW, Washington, DC 20005.
*                  *                  *                  *                  *                  *              *
\13\ Because MDLs reported in EPA Methods 200.7 and 200.9 were determined using a 2X preconcentration step
  during sample digestion, MDLs determined when samples are analyzed by direct analysis (i.e.,no sample
  digestion) will be higher. For direct analysis of cadmium and arsenic by Method 200.7, and arsenic by Method
  3120 B sample preconcentration using pneumatic nebulization may be required to achieve lower detection limits.
  Preconcentration may also be required for direct analysis of antimony, lead, and thallium by Method 200.9;
  antimony and lead by Method 3113 B; and lead by Method D3559-90D unless multiple in-furnace depositions are
  made.
\14\ If ultrasonic nebulization is used in the determination of arsenic by Methods 200.7, 200.8, or SM 3120 B,
  the arsenic must be in the pentavalent state to provide uniform signal response. For methods 200.7 and 3120 B,
  both samples and standards must be diluted in the same mixed acid matrix concentration of nitric and
  hydrochloric acid with the addition of 100 L of 30% hydrogen peroxide per 100ml of solution. For
  direct analysis of arsenic with method 200.8 using ultrasonic nebulization, samples and standards must contain
  one mg/L of sodium hypochlorite.
*                  *                  *                  *                  *                  *
   *

    (2) * * *

[[Page 38980]]



----------------------------------------------------------------------------------------------------------------
           Contaminant                       Preservative \1\              Container \2\           Time \3\
----------------------------------------------------------------------------------------------------------------
 
*                  *                  *                  *                  *                  *
                                                        *
Arsenic..........................  Conc HNO3 to pH 2..................  P or G.............  6 months.
 
*                  *                  *                  *                  *                  *
                                                       *
----------------------------------------------------------------------------------------------------------------
\1\ When indicated, samples must be acidified at the time of collection to pH 2 with concentrated acid or
  adjusted with sodium hydroxide to pH > 12. When chilling is indicated the sample must be shipped and stored at
  4 deg.C or less.
\2\ P = plastic, hard or soft; G=glass, hard or soft.
\3\ In all cases samples should be analyzed as soon after collection as possible. Follow additional (if any)
  information on preservation, containers or holding times that is specified in method.

* * * * * * *
    (3) * * *
    (ii) * * *

----------------------------------------------------------------------------------------------------------------
             Contaminant                    Acceptance limit
------------------------------------------------------------------
 
*                  *                  *                  *                  *                  *
                                                        *
Arsenic.............................  30 at 0.005 mg/l
 
*                  *                  *                  *                  *                  *
                                                        *
----------------------------------------------------------------------------------------------------------------

* * * * *
    6. Section 141.24 is amended by:
    a. Adding one sentence to the end of paragraph (f)(15)(i).
    b. Removing the last sentence of paragraph (f)(15)(ii) and adding 
in its place two new sentences.
    c. Adding paragraph (f)(22).
    d. Adding a sentence to the end of paragraph (h)(11)(i).
    e. Removing the last sentence of paragraph (h)(11)(ii) and adding 
in its place two new sentences.
    f. Adding paragraph (h)(20).
    The revisions and additions read as follows:


Sec. 141.24  Organic chemicals other than total trihalomethanes, 
sampling and analytical methods.

* * * * *
    (f) * * *
    (15) * * *
    (i) * * * If a system fails to collect the required number of 
samples, compliance (average concentration) will be based on the total 
number of samples collected.
    (ii) * * * If confirmation samples are required by the State, the 
determination of compliance will be based on the annual average of the 
initial MCL exceedance and any State-required confirmation samples. If 
a system fails to collect the required number of samples, compliance 
(average concentration) will be based on the total number of samples 
collected.
* * * * *
    (22) All new systems or systems that use a new source of water that 
begin operation after [DATE THREE YEARS AFTER PUBLICATION DATE OF FINAL 
RULE] must demonstrate compliance with the MCL within a period of time 
specified by the State. The system must also comply with the initial 
sampling frequencies specified by the State to ensure a system can 
demonstrate compliance with the MCL. Routine and increased monitoring 
frequencies shall be conducted in accordance with the requirements in 
this section.
* * * * *
    (h) * * *
    (11) * * *
    (i) * * * If a system fails to collect the required number of 
samples, compliance (average concentration) will be based on the total 
number of samples collected.
    (ii) * * * If confirmation samples are required by the State, the 
determination of compliance will be based on the annual average of the 
initial MCL exceedance and any State-required confirmation samples. If 
a system fails to collect the required number of samples, compliance 
(average concentration) will be based on the total number of samples 
collected.
* * * * *
    (20) All new systems or systems that use a new source of water that 
begin operation after [DATE THREE YEARS AFTER PUBLICATION OF THE FINAL 
RULE] must demonstrate compliance with the MCL within a period of time 
specified by the State. The system must also comply with the initial 
sampling frequencies specified by the State to ensure a system can 
demonstrate compliance with the MCL. Routine and increased monitoring 
frequencies shall be conducted in accordance with the requirements in 
this section.

Subpart F--[Amended]

    7. In Sec. 141.51(b) , the table is amended by adding in 
alphabetical order an entry for Arsenic to read as follows:


Sec. 141.51  Maximum contaminant level goals for inorganic 
contaminants.

* * * * *
    (b) * * *

------------------------------------------------------------------------
                Contaminant                          MCLG (mg/l)
------------------------------------------------------------------------
 
              *        *        *        *        *
Arsenic...................................  zero
 
              *        *        *        *        *
------------------------------------------------------------------------

Subpart G--[Amended]

    8. Section 141.60 is amended by adding paragraph (b)(4) to read as 
follows:


Sec. 141.60  Effective dates.

* * * * *
    (b) * * *
    (4) The compliance date for Sec. 141.62(b)(16) is [DATE 5 YEARS 
AFTER PUBLICATION DATE OF THE FINAL RULE] for community water systems 
serving 10,000 people or less, and [DATE 3 YEARS AFTER PUBLICATION DATE 
OF THE FINAL RULE] for all other community water systems.
    9. Section 141.62 is amended by:
    a. Revising the second sentence of paragraph (b).
    b. Adding entry ``(16)'' to the table in paragraph (b).
    c. Adding an entry and footnote for ``Arsenic'' in alphabetical 
order to the

[[Page 38981]]

table in paragraph (c) and revising the table heading.
    d. Adding paragraph (d).
    The revisions and additions read as follows:


Sec. 141.62  Maximum contaminant levels for inorganic contaminants.

* * * * *
    (b) * * * The maximum contaminant level specified in paragraphs 
(b)(1) and (b)(16) of this section only apply to community water 
systems. * * *

------------------------------------------------------------------------
                Contaminant                          MCL (mg/l)
------------------------------------------------------------------------
 
              *        *        *        *        *
(16) Arsenic..............................  0.005
------------------------------------------------------------------------

    (c) * * *

         Bat for Inorganic Compounds Listed in Section 141.62(b)
------------------------------------------------------------------------
             Chemical name                            BAT(s)
------------------------------------------------------------------------
 
*                  *                  *                  *
                  *                  *                  *
Arsenic \4\............................  1, 2, 5, 6, 7, 9
------------------------------------------------------------------------
* * * * * * *
\4\ BATs for Arsenic V. Pre-oxidation may be required to convert Arsenic
  III to Arsenic V.

    (d) The Administrator, pursuant to section 1412 of the Act, hereby 
identifies in the following table the affordable technology, treatment 
technique, or other means available to systems serving 10,000 persons 
or fewer for achieving compliance with the maximum contaminant level 
for arsenic:

    Small System Compliance Technologies (SSCTs) \1\ for Arsenic \2\
------------------------------------------------------------------------
   Small System Compliance         Affordable for listed small system
          Technology                         categories \3\
------------------------------------------------------------------------
Activated Alumina              All size categories
 (centralized).
Activated Alumina (Point-of-   All size categories
 Entry) \4\.
Activated Alumina (Point-of-   All size categories
 Use) \4\.
Coagulation/Filtration.......  501-3,300, 3,301-10,000
Coagulation-assisted           501-3,300, 3,301-10,000
 Microfiltration.
Ion Exchange.................  All size categories
Lime Softening...............  501-3,300, 3,301-10,000
Oxidation/Filtration \5\.....  All size categories
Reverse Osmosis (centralized)  501-3,300, 3,301-10,000
Reverse Osmosis (Point-of-     All size categories
 Use) \4\.
------------------------------------------------------------------------
\1\ Section 1412(b)(4)(E)(ii) of the SDWA specifies that SSCTs must be
  affordable and technically feasible for small systems.
\2\ SSCTs for Arsenic V. Pre-oxidation may be required to convert
  Arsenic III to Arsenic V.
\3\ The Act (ibid.) specifies three categories of small systems: (i)
  those serving 25 or more, but fewer than 501, (ii) those serving more
  than 500, but fewer than 3,301, and (iii) those serving more than
  3,300, but fewer than 10,001.
\4\ When POU or POE devices are used for compliance, programs to ensure
  proper long-term operation, maintenance, and monitoring must be
  provided by the water system to ensure adequate performance.
\5\ For use only when the removal efficiency needed to reach an MCL is
  less than 50%.

Subpart O--[Amended]

    10. Section 141.154 is amended by revising paragraph (b) to read as 
follows:


Sec. 141.154  Required additional health information.

* * * * *
    (b) Beginning [30 DAYS AFTER PUBLICATION DATE OF THE FINAL RULE], 
community water systems that detect arsenic above 0.005 mg/L must make 
a good faith effort, as described in Sec. 141.155(b) to provide to its 
customers an annual report that contains the information specified in 
Sec. 141.153 for arsenic.
* * * * *
    11. The table in Appendix A, published at 65 FR 26024 on May 4, 
2000 and effective June 5, 2000, is amended by revising the entry for 
arsenic to read as follows:

Appendix A to Subpart O.--Regulated Contaminants

* * * * *

[[Page 38982]]



--------------------------------------------------------------------------------------------------------------------------------------------------------
                                           Traditional   To convert
           Contaminant (units)             MCL  in mg/    for CCR,    MCL in CCR      MCLG       Major sources in drinking     Health effects language
                                                L       multiply by     units                              water
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                   *                  *                  *                  *                  *                  *                  *
Inorganic contaminants:
 
                   *                  *                  *                  *                  *                  *                  *
Arsenic (ppb)............................        0.005         1000            5            0  Erosion of natural deposits;  Some people who drink water
                                                                                                Runoff from orchards;         containing arsenic in
                                                                                                Runoff from glass and         excess of the MCL over
                                                                                                electronics production        many years could
                                                                                                wastes.                       experience skin damage or
                                                                                                                              problems with their
                                                                                                                              circulatory system, and
                                                                                                                              may have an increased risk
                                                                                                                              of getting cancer.
 
                  *                  *                  *                  *                  *                  *                  *
--------------------------------------------------------------------------------------------------------------------------------------------------------
Key:
*                  *                  *                  *                  *                  *                  *
ppb = parts per billion, or micrograms per liter (g/l)
*                  *                  *                  *                  *                  *                  *

Subpart Q--[Amended]

    12. Section 141.203(a), published at 65 FR 26036 on May 4, 2000, 
and effective June 5, 2000, is amended by adding entry (4) in numerical 
order to Table 1 to read as follows:


Sec. 141.203  Tier 2 Public Notice--Form, manner, and frequency of 
notice.

    (a) * * *

  Table 1 to Sec.  141.203.--Violation Categories and Other Situations
                    Requiring a Tier 2 Public Notice
------------------------------------------------------------------------
 
-------------------------------------------------------------------------
 
*                  *                  *                  *
                  *                  *                  *
(4) Non-transient non-community water systems exceeding the arsenic MCL.
------------------------------------------------------------------------

* * * * *
    13. Appendix A to Subpart Q, published at 65 FR 26040 on May 4, 
2000, effective June 5, 2000, is amended in the table by revising the 
entry for ``2. Arsenic'' under B. Inorganic Chemicals (IOCs), revising 
endnote 1 and adding endnotes 18 and 19 to read as follows:

Appendix A to Subpart Q of Part 141.--NPDWR Violations and Other 
Situations Requiring Public Notice\1\

----------------------------------------------------------------------------------------------------------------
                                                   MCL/MRDL/TT violations      Monitoring & testing procedure
                                                             \2\                         violations
                                                 ---------------------------------------------------------------
                   Contaminant                      Tier of                   Tier of
                                                     public                    public
                                                     notice      Citation      notice            Citation
                                                    required                  required
----------------------------------------------------------------------------------------------------------------
 
*                  *                  *                  *                  *                  *
                                                        *
B. Inorganic Chemicals (IOCs)
 
*                  *                  *                  *                  *                  *
                                                        *
2. Arsenic......................................            2  \18\ 141.62            3      \19\ 141.23(a), (c)
                                                                       (b)
 
*                  *                  *                  *                  *                  *
                                                        *
----------------------------------------------------------------------------------------------------------------

Appendix A--Endnotes

    1. Violations and other situations not listed in this table 
(e.g., reporting violations and failure to prepare Consumer 
Confidence Reports), do not require notice, unless otherwise 
determined by the primacy agency. Primacy agencies may, at their 
option, also require a more stringent public notice tier (e.g., Tier 
1 instead of Tier 2 or Tier 2 instead of Tier 3) for specific 
violations and situations listed in this Appendix, as authorized 
under Sec. 141.202(a) and Sec. 141.203(a).
    2. MCL--Maximum contaminant level, MRDL--Maximum residual 
disinfectant level, TT--Treatment technique.
* * * * *
    18. The arsenic MCL citations apply [DATE 5 YEARS AFTER 
PUBLICATION DATE OF THE FINAL RULE] for community water systems 
serving 10,000 people or less and [DATE 3 YEARS AFTER PUBLICATION 
DATE OF THE FINAL RULE] for all other community water systems and 
non-transient non-community water systems. Until then, the citations 
are Sec. 141.11(b) and Sec. 141.23(n).
    19. The arsenic Tier 3 violation MCL citations apply [DATE 5 
YEARS AFTER PUBLICATION DATE OF THE FINAL RULE] for community water 
systems serving 10,000 people or less and [DATE 3 YEARS AFTER 
PUBLICATION DATE OF THE FINAL RULE] for all other community water 
systems. Until then, the citations are Sec. 141.23(a,l).

    14. Appendix B to Subpart Q published at 65 FR 26043 on May 4, 
2000, effective June 5, 2000, is amended in the table by revising entry 
``9. Arsenic'' and adding footnote 23 to read as follows:

Appendix B to Subpart Q of Part 141.--Standard Health Effects Language 
for Public Notification

[[Page 38983]]



----------------------------------------------------------------------------------------------------------------
                                                MCLG\1\  mg/               Standard health effects language for
                  Contaminant                        L       MCL\2\ mg/L            public notification
----------------------------------------------------------------------------------------------------------------
 
*                  *                  *                  *                  *                  *
                                                        *
9. Arsenic \23\...............................            0        0.005  Some people who drink water containing
                                                                           arsenic in excess of the MCL over
                                                                           many years could experience skin
                                                                           damage or problems with thier
                                                                           circulatory system, and may have an
                                                                           increased risk of getting cancer.
 
*                  *                  *                  *                  *                  *
                                                        *
----------------------------------------------------------------------------------------------------------------

Appendix B--Endnotes

    1. MCLG--Maximum contaminant level goal.
    2. MCL--Maximum contaminant level.
* * * * *
    23. These arsenic values apply [DATE 5 YEARS AFTER PUBLICATION 
DATE OF THE FINAL RULE] for community water systems serving 10,000 
people or less and [DATE 3 YEARS AFTER PUBLICATION DATE OF THE FINAL 
RULE] for all other community water systems and non-transient non-
community water systems. Until then, the MCL is 0.050 mg/L and there 
is no MCLG.

PART 142--NATIONAL PRIMARY DRINKING WATER REGULATIONS 
IMPLEMENTATION

    1. The authority citation for part 142 continues to read as 
follows:

    Authority: 42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-
5, 300g-6, 300j-4, 300j-9, and 300j-11.

Subpart B--Primary Enforcement Responsibility

    2. In Sec. 142.16, revise paragraph (e) introductory text and add 
paragraphs (j) and (k) to read as follows:


Sec. 142.16  Special primacy requirements.

* * * * *
    (e) An application for approval of a State program revision which 
adopts the requirements specified in Secs. 141.11, 141.23, 141.24, 
141.40, 141.61 and 141.62 for a newly regulated contaminant must 
contain the following (in addition to the general primacy requirements 
enumerated elsewhere in this part, including the requirement that State 
regulations be at least as stringent as the federal requirements):
* * * * *
    (j) An application for approval of a State program revision which 
adopts the requirements specified in Secs. 141.11, 141.23, 141.24, 
141.32, 141.40, 141.61 and 141.62 for an existing regulated contaminant 
must contain the following (in addition to the general primacy 
requirements enumerated elsewhere in this part, including the 
requirement that State regulations be at least as stringent as the 
federal requirements):
    (1) If a State chooses to issue waivers from the monitoring 
requirements in Secs. 141.23, 141.24, and 141.40, the State shall 
describe the procedures and criteria which it will use to review waiver 
applications and issue wavier determinations. The State shall provide 
the same information required in paragraphs (e)(1)(i) and (ii) of this 
section. States may update their existing waiver criteria or use the 
requirements submitted under the National Primary Drinking Water 
Regulations for the inorganic and organic contaminants (i.e., Phase II/
V rule) in paragraph (e) of this section. States may simply note in 
their application any revisions to existing waiver criteria or note 
that the same procedures to issue waivers will be used.
    (2) A monitoring plan by which the State will assure all systems 
complete the required monitoring with the regulatory deadlines. States 
may update their existing monitoring plan or use the same monitoring 
plan submitted under the National Primary Drinking Water Regulations 
for the inorganic and organic contaminants (i.e. Phase II/V rule) in 
paragraph (e) of this section. States may simply note in their 
application any revisions to an existing monitoring plan or note that 
the same monitoring plan will be used. The State must demonstrate that 
the monitoring plan is enforceable under State law.
    (k) States establish the initial monitoring requirements for new 
systems and new sources. States must explain their initial monitoring 
schedules and how these monitoring schedules ensure that public water 
systems and sources that begin operation after [DATE THIRTY DAYS AFTER 
PUBLICATION OF THE FINAL RULE] comply with MCL's and monitoring 
requirements. States must also specify the time frame in which new 
systems will demonstrate compliance with the MCLs.
    4. In Sec. 142.62(b), the table is amended by revising the table 
heading and adding arsenic in alphabetical order to the list of 
contaminants to read as follows:


Sec. 142.62  Variances and exemptions from the maximum contaminant 
levels for organic and inorganic chemicals

* * * * *
    (b) * * *

        BAT for Inorganic Compounds Listed in Sec.  141.62(b) \1\
------------------------------------------------------------------------
             Chemical name                            BAT(s)
------------------------------------------------------------------------
 
*                *                *                *                *
                                  *                *
Arsenic................................  1, 2, 5, 6, 7, 9
 
*                *                *                *                *
                                  *                *
------------------------------------------------------------------------

* * * * *

Key to BATs in Table

1 = Activated Alumina
2 = Coagulation/Filtration (not BAT for systems  500 service 
connections)
* * * * *
5 = Ion Exchange
6 = Lime Softening (not BAT for systems  500 service connections)
7 = Reverse Osmosis
* * * * *
9 = Electrodialysis
* * * * *
[FR Doc. 00-13546 Filed 6-21-00; 8:45 am]
BILLING CODE 6560-50-P