[Federal Register Volume 68, Number 138 (Friday, July 18, 2003)]
[Notices]
[Pages 42907-42929]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-18152]



[[Page 42907]]

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Part VI





Environmental Protection Agency





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National Primary Drinking Water Regulations; Announcement of Completion 
of EPA's Review of Existing Drinking Water Standards; Notice

Federal Register / Vol. 68, No. 138 / Friday, July 18, 2003 / 
Notices

[[Page 42908]]


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ENVIRONMENTAL PROTECTION AGENCY

[FRL-7529-1]
RIN 2040-AD67


National Primary Drinking Water Regulations; Announcement of 
Completion of EPA's Review of Existing Drinking Water Standards

AGENCY: Environmental Protection Agency.

ACTION: Notice.

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SUMMARY: The Safe Drinking Water Act (SDWA) requires the United States 
Environmental Protection Agency (EPA) to conduct a periodic review of 
existing National Primary Drinking Water Regulations (NPDWRs). EPA has 
completed its review of 69 NPDWRs that were established prior to 1997, 
including 68 chemical NPDWRs and the Total Coliform Rule (TCR). The 
intended purpose of the review was to identify those NPDWRs for which 
current health risk assessments, changes in technology, and/or other 
factors, provide a health or technological basis to support a 
regulatory revision that will maintain or improve public health 
protection.
    EPA published its protocol for the review of NPDWRs and its 
preliminary revise/not revise decisions for the 69 NPDWRs in the April 
17, 2002, edition of the Federal Register (67 FR 19030 (USEPA, 2002g)) 
in order to seek comment from the public. Today's action briefly 
describes the major comments, other new information, and EPA's current 
revise/not revise decisions for the 69 NPDWRs.

ADDRESSES: The official public docket for this action is located at EPA 
West Building, Room B102, 1301 Constitution Avenue, NW., Washington, 
DC.

FOR FURTHER INFORMATION CONTACT: Contact: Ken Rotert, (202) 564-5280, 
e-mail: [email protected] for inquiries regarding the TCR. For all 
other technical inquiries contact: Judy Lebowich, (202) 564-4884, e-
mail: [email protected], or Wynne Miller, (202) 564-4887, e-mail: 
[email protected]. General information may also be obtained from the 
EPA Safe Drinking Water Hotline. Callers within the United States may 
reach the Hotline at (800) 426-4791. The Hotline is open Monday through 
Friday, excluding Federal holidays, from 9 a.m. to 5:30 p.m. Eastern 
Time.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. General Information
    A. Does this Notice Apply to My Public Water System?
    B. How Can I Get Copies of Related Information?
    1. Docket
    2. Electronic Access
II. Background
    A. What Is the Statutory Requirement for the Six-Year Review?
    B. What Has the Agency Done to Address the Statutory 
Requirement?
III. EPA's Current Revise/Not Revise Decisions for the 69 Pre-1997 
NPDWRs
IV. Summary of Major Comments and New Information and the Agency's 
Response
    A. What Did Commenters Say Regarding the Reasonableness and 
Appropriateness of EPA's Six-Year Review Approach?
    1. Overall Approach and Decision Criteria
    2. Health Effects Technical Review
    3. Analytical Methods Feasibility Technical Review
    4. Review of Treatment Technologies and Related Issues
    5. Review of Implementation-Related Issues
    6. Review of Occurrence and Exposure
    7. Consideration of Available Economic Information
    B. What Comments or New Information Did EPA Receive on Chemical 
Contaminant-Specific Issues?
    1. Alachlor
    2. Antimony
    3. Atrazine
    4. Beryllium
    5. Carbofuran
    6. Chromium
    7. 1,1-Dichloroethylene
    8. Dichloromethane
    9. Di(2-ethylhexyl)adipate (DEHA)
    10. Di(2-ethylhexyl)phthalate (DEHP)
    11. Fluoride
    12. Glyphosate
    13. Lead and Copper
    14. Lindane ([gamma]-hexachlorocyclohexane)
    15. Simazine
    C. What Comments Did EPA Receive Regarding the Review of 
Implementation-Related Issues for Chemical NPDWRs?
    D. What Comments Did EPA Receive on the Total Coliform Rule?
    E. What Comments Did EPA Receive on Research Needs?
V. References

List of Tables

Table III-1: Current Revise/Not Revise Decisions for the 68 Chemical 
NPDWRs and the TCR
Table IV-1: 1,1-Dichloroethylene Occurrence
Table IV-2: Lindane Occurrence

I. General Information

A. Does This Notice Apply to My Public Water System?

    This action itself does not impose any requirements on anyone. 
Instead, it notifies interested parties of the availability of EPA's 
responses to comments received on EPA's Six-Year Review protocol and 
the Agency's current revise/not revise decisions for 69 NPDWRs.

B. How Can I Get Copies of Related Information?

1. Docket
    EPA has established an official public docket for this action under 
Docket ID No. OW-2002-0012. The official public docket consists of the 
documents specifically referenced in this action, any public comments 
received, and other information related to this action. Although a part 
of the official docket, the public docket does not include Confidential 
Business Information (CBI) or other information whose disclosure is 
restricted by statute. The official public docket is the collection of 
materials that is available for public viewing at the Water Docket in 
the EPA Docket Center, (EPA/DC) EPA West, Room B102, 1301 Constitution 
Ave., NW., Washington, DC. The EPA Docket Center Public Reading Room is 
open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding 
legal holidays. The telephone number for the Public Reading Room is 
(202) 566-1744, and the telephone number for the Water Docket is (202) 
566-2426.
2. Electronic Access
    You may access this Federal Register document electronically 
through the EPA Internet under the ``Federal Register'' listings at 
http://www.epa.gov/fedrgstr/.
    An electronic version of the public docket is available through 
EPA's electronic public docket and comment system, EPA Dockets. You may 
use EPA Dockets at http://www.epa.gov/edocket/ to view public comments, 
access the index listing of the contents of the official public docket, 
and access those documents in the public docket that are available 
electronically. Although not all docket materials may be available 
electronically, you may still access any of the publicly available 
docket materials through the docket facility identified in section 
I.B.1. Once in the system, select ``search,'' then key in the 
appropriate docket identification number.

Abbreviations and Acronyms Used in This Action

BAT--best available technology
CBI--confidential business information
CCL--contaminant candidate list
CFR--Code of Federal Regulations
CMR--Chemical Monitoring Reform
DACT--diaminochlorotriazine
DEA--desethyl atrazine
DEHA--di(2-ethylhexyl)adipate
DEHP--di(2-ethylhexyl)phthalate
DIA--desisopropyl atrazine
EPA--United States Environmental Protection Agency

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EPA/DC--EPA Docket Center
FQPA--Food Quality Protection Act
FR--Federal Register
IOC--inorganic chemical
IRED--interim reregistration eligibility decision
IRIS--Integrated Risk Information System
LCCA--Lead Contamination Control Act of 1988
LCR--Lead and Copper Rule
MCL--maximum contaminant level
MCLG--maximum contaminant level goal
MDL--method detection limit
mg/kg/day--milligram(s) per kilogram of body weight per day
mg/L--milligram(s) per liter
MYP--multi-year plan
NAS--National Academy of Sciences
NCOD--National Contaminant Occurrence Database
NDWAC--National Drinking Water Advisory Council
NPDWR--National Primary Drinking Water Regulation
NRC--National Research Council
NTP--National Toxicology Program
NTNCWS--non-transient non-community water system
Occurrence Methodology Document--Occurrence Estimation Methodology and 
Occurrence Findings Report for the Six-Year Review of Existing National 
Primary Drinking Water Regulations
Occurrence Summary Document--Occurrence Summary and Use Support 
Document for the Six-Year Review of Existing National Primary Drinking 
Water Regulations
OPP--Office of Pesticide Programs
OW--Office of Water
PE--performance evaluation
PHS--Public Health Service
PQL--practical quantitation level
Protocol Document--EPA Protocol for Review of Existing National Primary 
Drinking Water Regulations
RED--reregistration eligibility decision
RfD--reference dose
ROS--regression on ordered statistics
RSC--relative source contribution
SAB--Science Advisory Board
SAP--Science Advisory Panel
SDWA--Safe Drinking Water Act
SOC--synthetic organic chemical
TCR--Total Coliform Rule
TMDLs--total maximum daily loads
Treatment Feasibility Document--Water Treatment Technology Feasibility 
Support Document for Chemical Contaminants; In Support of EPA Six-Year 
Review of National Primary Drinking Water Regulations
TT--treatment technique
VOC--volatile organic chemical
WQP--water quality parameter
WS--water supply

II. Background

A. What Is the Statutory Requirement for the Six-Year Review?

    Under the Safe Drinking Water Act (SDWA), as amended in 1996, EPA 
must periodically review existing National Primary Drinking Water 
Regulations (NPDWRs) and, if appropriate, revise them. Section 
1412(b)(9) of SDWA states:

    The Administrator shall, not less often than every 6 years, 
review and revise, as appropriate, each national primary drinking 
water regulation promulgated under this title. Any revision of a 
national primary drinking water regulation shall be promulgated in 
accordance with this section, except that each revision shall 
maintain, or provide for greater, protection of the health of 
persons.

B. What Has the Agency Done To Address the Statutory Requirement?

    The Agency developed a systematic process, or protocol, for the 
review of existing NPDWRs in accordance with the SDWA requirements and 
applied the protocol to the review of the NPDWRs for total coliforms 
and 68 inorganic and organic chemicals published prior to the SDWA 1996 
Amendments (i.e., pre-1997 NPDWRs). In the April 17, 2002, Federal 
Register, EPA provided:
    [sbull] A description of the review protocol;
    [sbull] A detailed discussion of how the protocol was applied in 
assessing each of the 69 pre-1997 NPDWRs;
    [sbull] The preliminary results of each of the technical reviews, 
and the preliminary decision for each NPDWR; and
    [sbull] A request for the public to comment on any aspect of the 
Agency's protocol and preliminary decisions.
    Please refer to the April 17, 2002, Federal Register for the 
detailed discussion of EPA's revise/not revise decisions for each of 
the 69 NPDWRs. Today's action briefly summarizes the major public 
comments, other new information, and EPA's current revise/not revise 
decisions for the 69 NPDWRs. Today's action only discusses in detail 
those decisions or rationales that were affected by public comments or 
other new information that has become available since April 2002.
    In June 2002, EPA consulted with the Science Advisory Board (SAB) 
Drinking Water Committee and requested their review and comment on 
whether the protocol EPA developed based on the National Drinking Water 
Advisory Council (NDWAC) recommendations was consistently applied and 
appropriately documented. The SAB provided verbal feedback regarding 
the transparency and clarity of EPA's decision criteria for making its 
revise/not revise decisions under the current review. EPA has revised 
this protocol document to better explain how the decision criteria were 
applied and will also take the SAB comments into consideration when 
planning for the next review cycle.

III. EPA's Current Revise/Not Revise Decisions for the 69 Pre-1997 
NPDWRs

    EPA received comments from 44 commenters on its preliminary revise/
not revise decisions in the April 17, 2002, Federal Register. The 
Agency responded to these comments in the ``Public Comment and Response 
Summary for the Six-Year Review of National Primary Drinking Water 
Regulations'' (USEPA, 2003e), which is available in the Water Docket in 
the EPA Docket Center and at the EPA Dockets Web site http://www.epa.gov/epadocket/. Other technical support documents \1\ for the 
decisions discussed in today's action are also available in the Water 
Docket and at the EPA Dockets Web site http://www.epa.gov/epadocket/ 
and the Safewater Web site http://www.epa.gov/safewater/.
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    \1\ These include: (1) EPA's overall protocol for the review of 
NPDWRs (USEPA, 2003c); (2) health effects (USEPA, 2003f); (3) 
analytical methods feasibility (USEPA, 2003a); (4) treatment 
technology (USEPA, 2003g); (5) consideration of other regulatory 
revisions (USEPA, 2003b); (6) occurrence and exposure (USEPA, 2003d; 
USEPA, 2002f); (7) and economic considerations (USEPA, 2002c).
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    Based on the Agency's preliminary review, as well as the public 
comments received and other new information, EPA believes that it is 
appropriate to revise the Total Coliform Rule (TCR). The Agency also 
believes that it is not appropriate to revise the 68 chemical NPDWRs at 
this time. However, for the reasons discussed in sections IV.B.7, 
IV.B.13, and IV.B.14 of today's action, the Agency has modified the 
basis of its not revise findings for 1,1-dichloroethylene, lead, and 
lindane, respectively. Table III-1 reflects the Agency's current 
revise/not revise decisions for the 69 NPDWRs. As indicated in Table 
III-1, EPA's decision not to revise an NPDWR at this time is based on 
one of the following reasons:
    [sbull] Health risk assessment is in process: As of December 31, 
2002, the Agency is currently conducting, or has scheduled, a detailed 
review of current health effects information. Because the results of 
the assessment are not yet available, or were not available in time for 
consideration under the 1996-2002 review cycle, the Agency does not 
believe it is appropriate to revise the NPDWR at this time. In these 
cases, EPA will consider the results of the updated

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health risk assessment during the 2002-2008 review cycle. If the 
results of the health risk assessment indicate a compelling reason to 
reconsider the maximum contaminant level goal (MCLG), EPA may decide to 
accelerate the review schedule for that contaminant's NPDWR.
    [sbull] NPDWR remains appropriate after data/information review: 
The outcome of the review indicates that the current regulatory 
requirements remain appropriate, and therefore, no regulatory revisions 
are warranted. Any new information available to the Agency either 
supports the current regulatory requirements or does not justify a 
revision.
    [sbull] New information, but no revision appropriate at this time 
because:

--Low priority: In EPA's judgment, any resulting revisions to the NPDWR 
would not provide a meaningful opportunity for health risk reduction or 
result in meaningful cost-savings to public water systems and their 
customers. These revisions are a low priority activity for the Agency 
and, thus, are not appropriate for revision at this time because of one 
or more of the following considerations: competing workload priorities; 
the administrative costs associated with rulemaking; and the burden on 
States and the regulated community to implement any regulatory change 
that resulted.
--Information gaps: Although results of the review support 
consideration of a possible revision, the available data are 
insufficient to support a definitive regulatory decision at this time.
BILLING CODE 6560-50-P

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[GRAPHIC] [TIFF OMITTED] TN18JY03.070

BILLING CODE 6560-50-C

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IV. Summary of Major Comments and New Information and the Agency's 
Response

    This section summarizes the major public comments, including the 
Agency's response, and other new information, and explains any 
modifications to EPA's preliminary revise/not revise decisions. For a 
more detailed summary of the comments and the Agency's response, please 
refer to the document: ``Public Comment and Response Summary for the 
Six-Year Review of National Primary Drinking Water Regulation'' (USEPA, 
2003e).

A. What Did Commenters Say Regarding the Reasonableness and 
Appropriateness of EPA's Six-Year Review Approach?

1. Overall Approach and Decision Criteria
    a. Adequacy of the Review. Commenters generally agreed that EPA had 
identified the appropriate key elements of the review. However, some 
commenters stated that the Agency could have done more in some areas 
(e.g., implementation) and a few commenters expressed the opinion that 
the Agency's review process contains weaknesses, or was not applied 
appropriately, because it did not identify any chemical NPDWRs for 
revision at this time.
    EPA Response: The Agency believes that its basic review protocol 
and decision rationale are reasonable and appropriate. Even though 
EPA's application of the protocol did not identify any chemical NPDWRs 
for revision at this time, that is not a reason to reject or modify the 
protocol. The review did result in the initiation of health risk 
assessments for three contaminants and efforts to address data gaps/
research needs for several other contaminants. Health risk assessments 
are underway for approximately half of the chemical contaminants 
addressed in today's action. The Agency expects most of these 
assessments to be completed within the next few years. When completed, 
these assessments will support further analysis that may result in 
different revise/not revise decisions as part of the ongoing Six-Year 
Review process.
    b. Criteria for Deciding that an MCLG/MCL Revision is Appropriate 
and Definition of ``Significant'' and ``Negligible.'' While some 
commenters agreed, others disagreed with the Agency's consideration of 
estimated changes in occurrence levels and available economic 
information whenever a health or technological basis exists to revise a 
standard. For example, some commenters felt that EPA should revise the 
MCLG and, as appropriate, the maximum contaminant level (MCL), whenever 
a health basis exists, regardless of other considerations. A few 
commenters criticized the Agency for not defining what it considers 
``significant'' and ``negligible'' gains in public health protection 
and/or cost-savings in terms of regulatory revision.
    EPA Response: Section 1412(b)(9) of SDWA, as amended in 1996, 
provides the Administrator with broad discretion to determine when a 
revision to an NPDWR is appropriate. As a part of this determination, 
the Agency believes it is reasonable to consider whether a potential 
revision is likely to provide a meaningful opportunity for health risk 
reduction. This criterion is consistent with the statutory provisions 
governing the regulatory determination process under section 
1412(b)(1)(A) for contaminants not currently regulated. EPA also 
believes it is reasonable to consider the extent of potential cost-
savings for public water systems and their customers when determining 
whether revisions that potentially would result in a relaxed standard 
(i.e., where a health basis exists for a less stringent standard) or 
streamlined implementation are appropriate. These considerations allow 
the Administrator to better prioritize efforts that are most likely to 
result in a meaningful opportunity for health risk reduction or cost-
savings to public water systems and their customers. Revisions that do 
not satisfy at least one of these criteria are a low priority activity 
for the Agency, and thus are not appropriate at this time because of 
one or more of the following considerations:
    [sbull] Competing workload priorities;
    [sbull] The administrative costs associated with rulemaking; and
    [sbull] The burden on States and the regulated community to 
implement any regulatory change that resulted.
    EPA believes that the determination of whether the impact of a 
potential revision is ``significant'' or ``negligible'' is a matter of 
judgment that depends on a number of variables, not all of which are 
amenable to precise definition. However, EPA recognizes that the use of 
``negligible/significant'' terminology may imply more precision and 
quantitation in the determination than is possible. The Agency also 
understands that the use of the term ``negligible'' may imply to some 
that the Agency is belittling small gains in health risk reduction. 
This is not the Agency's intent. Accordingly, in today's action, the 
Agency has explained its rationale more clearly in terms of the 
criteria noted in the previous paragraph.
    c. Authority to Relax an Existing Standard and Deregulation of Low/
Non-Occurring Contaminants. Some commenters argued that the Agency 
should never consider relaxing a standard because doing so, by 
definition, would lessen the level of public health protection. Other 
commenters encouraged the Agency to actively consider deregulating 
contaminants that have low occurrence or do not appear to be occurring 
in finished water or, at a minimum, to further reduce the frequency of 
monitoring for these contaminants.
    EPA Response: EPA disagrees with those commenters who oppose 
relaxing a standard for any reason. The legislative history of the SDWA 
Amendments of 1996 makes clear that Congress envisioned the possibility 
that a relaxed standard might be appropriate under circumstances that 
would not result in a lessening of the level of public health 
protection. In its discussion of potential revisions to an existing 
drinking water standard, Senate Report Number 104-169 (available 
electronically at http://thomas.loc.gov/) states:

    Amendments made by the bill require that any future standard 
issued for a contaminant already regulated must maintain or provide 
for greater protection of the health of persons. Generally, this 
will preclude the promulgation of a revised standard for a 
contaminant that is less stringent than the standard already in 
place. However, there are circumstances under which a standard may 
be relaxed. The maximum contaminant level goal for a contaminant is 
set at a level at which there is no adverse effect on the health of 
persons with an adequate margin of safety. New scientific 
information may cause the MCLG to be revised and in some cases these 
revisions may be to less stringent levels. This may lead to a 
revision of the maximum contaminant level since it need be no more 
stringent than the MCLG. New information may also allow for a 
smaller margin of safety because it narrows the range of uncertainty 
for estimates of health risks. Finally, some substances which have 
been regulated as carcinogens for ingestion in drinking water may be 
reclassified (as asbestos has been in the most recent revision) or 
assigned a threshold for the effect based on new scientific 
information. In each of these cases, EPA may issue a revised 
standard for a contaminant that is less stringent than the one it 
replaces.

(S. Rep.104-169, 104th Cong., 1st Sess. (1995) at 38)

    However, because section 1412(b)(9) of SDWA requires that any 
revision to an existing NPDWR maintain or improve the level of public 
health protection, EPA believes that a clear, technically-based 
demonstration

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regarding the absence of potential risk is necessary to deregulate a 
contaminant. EPA does not believe it is appropriate to deregulate any 
currently regulated contaminant at this time because the Agency is not 
able to make a determination, pursuant to section 1412(b)(9) of SDWA, 
that there would be no lessening of public health protection if the 
contaminant were deregulated. The Agency disagrees that evaluation of 
finished water data is sufficient to consider deregulation of low or 
non-occurring contaminants. The apparent low or non-occurrence of these 
contaminants in finished water may be the result of effective treatment 
processes in place rather than the lack of occurrence in source water.
    EPA believes that the existing waiver provisions in the SDWA 
regulations give States sufficient flexibility to reduce or potentially 
eliminate monitoring of a chemical contaminant, where appropriate. 
States that have primacy for the drinking water regulations are 
responsible for their waiver programs and can grant waivers if a 
particular pesticide or herbicide has not been previously used, 
manufactured, stored, transported, or disposed in the area, a system's 
source water is not susceptible to contamination from the chemical, or 
the State has determined the system is not vulnerable. The State can 
grant waivers for individual contaminants, a group of contaminants, or 
issue an area-wide waiver (see 40 CFR 141.23 (b) and (c), and 141.24 
(f) and (h)). In addition, States can adopt alternative monitoring 
strategies as long as the approach is as stringent as the Federal 
requirements (USEPA, 1997b).
2. Health Effects Technical Review
    a. Contaminants Undergoing Health Risk Assessments. A few 
commenters raised issues with respect to the 36 chemical contaminants 
for which health risk assessments were underway when EPA published its 
preliminary revise/not revise decisions in the April 17, 2002, Federal 
Register. In particular, these commenters wanted to know the process 
that EPA plans to follow to review each NPDWR once the risk assessment 
is completed, including when that review would occur and when an 
accelerated review would be appropriate.
    EPA Response: Between April and August 2002, the Agency completed 
health risk assessments for 2 of the 36 contaminants: 1,1-
dichloroethylene and lindane. The results of those assessments and the 
impact on the Agency's revise/not revise decisions are discussed in 
sections IV.B.7 and IV.B.14, respectively, of today's action. NPDWRs 
for the remaining contaminants for which health risk assessments are in 
process will be reviewed as a part of the 2002-2008 review cycle. 
However, if in the Agency's judgment, a compelling reason exists to 
revisit the ``not revise'' decision sooner, EPA may accelerate the 
review cycle for that NPDWR. In reviewing these regulations, EPA 
expects to apply an approach consistent with the protocol used for the 
current review. That is, the Agency will consider the same key elements 
and apply the same basic decision tree for making a revise/not revise 
decision. The key elements of the review include health effects 
technical review, technology review, other regulatory revisions review, 
and, if appropriate, occurrence/exposure analyses and consideration of 
available economic information (see 67 FR 19030 at 19038, April 17, 
2002 (USEPA, 2002g)).
    b. Other Issues Related to the Health Effects Technical Review. One 
commenter stated that the Agency risk assessments underestimate risk 
because absorption of chemicals through the skin, lung, and nose is not 
``adequately'' taken into account. Another commenter encouraged the 
Agency to evaluate the literature for potential reproductive and 
developmental effects for chemicals with zero MCLGs since risk 
management strategies, such as monitoring frequency or treatment 
requirements, may be affected by such information.
    EPA Response: EPA disagrees that the Agency underestimates risk 
when deriving MCLGs. The Agency takes multiple routes of exposure into 
account by including a relative source contribution (RSC) in its 
calculation of an MCLG value. The RSC compares exposure from air, food, 
and drinking water and uses the data in allocating a portion of the 
total exposure to drinking water. When exposure data for the chemical 
are not available, EPA assumes that the RSC from drinking water is 20 
percent of the total exposure. This allows 80 percent of the total 
exposure to come from sources other than drinking water, such as 
exposure from food, inhalation, or dermal contact.
    EPA recognizes the possibility that some chemicals with zero MCLGs 
may also be of reproductive and/or developmental concern. EPA is 
investigating these endpoints and their potential impact on monitoring 
frequency or treatment requirements. However, the Agency does not 
believe the analysis can be completed during the current review cycle 
without significantly delaying the current revise/not revise decisions. 
To the extent possible, EPA will consider the results of this analysis 
and any additional information during subsequent Six-Year Reviews.
3. Analytical Methods Feasibility Technical Review
    Commenters generally supported the Agency's approach of using 
Performance Evaluation (PE) Water Supply (WS) data and the 10 times 
method detection limit (MDL) multiplier to evaluate possible changes in 
analytical feasibility for several of the contaminants under this Six-
Year Review. A few commenters agreed that the WS data are a valuable 
source of information for evaluating interlaboratory performance and 
for developing practical quantitation levels (PQLs). However, the same 
commenters questioned whether the approach of using PE WS data will be 
possible for future reviews since the Agency's laboratory certification 
program that once collected this information has been externalized to 
private providers. These commenters questioned whether the externalized 
or privatized data would be sufficient for the determination and/or re-
evaluation of PQLs. In addition, at least one commenter suggested that 
it may be appropriate (in the next Six-Year Review) to re-evaluate the 
policy of basing the PQL on only EPA Regional and State laboratory 
results, and recommended that the Agency include commercial and large 
utility laboratory results. According to the commenter, these 
laboratories (commercial and large utility) have demonstrated 
``significant innovation in method development and improved 
quantitation.''
    EPA Response: EPA agrees that the WS studies have been a valuable 
source of information for determining PQLs. At this time, the Agency 
has not determined whether the privatized data will be sufficient for 
the purposes mentioned by the commenter. In addition, the Agency has 
not yet determined how best to gather data to determine and/or reassess 
PQLs for future reviews. The Agency is in the process of evaluating 
acceptable options. The policy for determining the most appropriate 
methodology for calculating PQLs for drinking water contaminants is 
outside the scope of the Six-Year Review.
4. Review of Treatment Technologies and Related Issues
    Commenters suggested that, while EPA's review of existing NPDWRs 
was generally consistent with the NDWAC recommendations to EPA (NDWAC, 
2000), the Agency's review of treatment

[[Page 42914]]

technologies which support the regulations should be expanded. 
Specifically, commenters recommended that EPA review all treatment 
technique (TT) requirements and allow for changing or expanding these 
TT requirements where new information warrants such a change.
    EPA Response: EPA continues to believe its approach to reviewing TT 
requirements is appropriate. The ``EPA Protocol for the Review of 
Existing NPDWRs'' (Protocol Document) discusses when it is appropriate 
for the Agency to consider revisions to TT-type regulations (see 
sections II.C and III.B of the Protocol documents) (USEPA, 2002d; 
USEPA, 2003c). The Agency discussed the review of the four chemical 
treatment technique NPDWRs (i.e., acrylamide, copper, epichlorohydrin, 
and lead) in both the draft and final ``Water Treatment Technology 
Feasibility Support Document for Chemical Contaminants; In Support of 
EPA Six-Year Review of National Primary Drinking Water Regulations'' 
(Treatment Feasibility Documents) (USEPA, 2002b; USEPA, 2003g). The 
Agency has no specific information that provides a basis for revisions 
to TT requirements at this time. However, EPA believes that research 
data in a number of treatment-related areas may be useful in future 
reviews of NPDWRs. The Agency is committed to working with stakeholders 
to identify and prioritize treatment-related research needs, and to 
work with EPA's research partners to address the highest priority 
needs.
5. Review of Implementation-Related Issues
    While several commenters felt overall that EPA's Six-Year Review 
protocol was reasonable and appropriate, they encouraged EPA to 
consider implementation-related modifications (i.e., ``other regulatory 
revisions'') as a reason to revise a rule, even if there were no basis 
to revise the MCLG and/or MCL/TT requirements.
    EPA Response: Implementation-related issues are the primary reason 
for the Agency's decision to revise the TCR at this time (67 FR 19030 
at 19085, April 17, 2002 (USEPA, 2002g)), so it is clear that EPA 
considered implemented-related issues in its review. The Protocol 
Document (USEPA, 2002d; USEPA, 2003c) identifies the conditions under 
which the Agency will consider implementation-related revisions. EPA 
continues to believe these criteria are appropriate. During the current 
review, none of the identified potential implementation-related 
revisions pertaining to the chemical NPDWRs, in EPA's judgment, met the 
stated criteria for reasons documented in EPA's final document, 
``Consideration of Other Regulatory Revisions for Chemical Contaminants 
in Support of the Six-Year Review of National Primary Drinking Water 
Regulations'' (USEPA, 2003b).
6. Review of Occurrence and Exposure
    a. Occurrence Database Concerns. A few commenters asked for 
information regarding next steps for the National Contaminant 
Occurrence Database (NCOD). Another commenter pointed out that States 
have been willing to assist EPA by providing occurrence data beyond 
what is required of them. However, the commenter raised concerns that 
he/she felt EPA needs to address to facilitate further data sharing.
    Some commenters expressed concern about the completeness and 
representativeness of the 16-State data set used for the Six-Year 
Review. One commenter suggested that the Agency should have issued an 
Information Collection Request to obtain more complete data for the 
Six-Year Review analysis.
    EPA Response: The Agency is updating the NCOD to provide sample 
data that have been quality checked and used in various EPA analyses. 
This update to NCOD includes unregulated occurrence data collected 
prior to 1999 as well as the latest Unregulated Contaminant Monitoring 
Rule data (64 FR 50556, September 17, 1999 (USEPA, 1999b)) reported by 
laboratories for public water systems required to report results. It 
also includes the data used for the Six-Year Review of regulated 
contaminants. EPA appreciates that some States are willing to share 
their full compliance monitoring records with the Agency, even though 
it is not required. The Agency and the States are continuing to work 
together to establish a protocol for data sharing, including safeguards 
to prevent misuse and misinterpretation of data.
    The 16-State cross-section data set compiled for occurrence 
analyses for the Six-Year Review is the largest compliance monitoring 
data set for drinking water assembled by EPA to date. The design and 
construction of the 16-State cross-section data set was based on the 
fact that contaminant occurrence varies spatially (geographically) due 
to differing patterns of population, land use, chemical use, geology, 
hydrology, and climate. The detailed description of the ``pollution-
potential'' and geographic diversity considerations, and the derived 
balanced cross-section of States (that was developed to be collectively 
indicative of national occurrence) is included in the ``Occurrence 
Estimation Methodology and Occurrence Findings Report for the Six-Year 
Review of Existing National Primary Drinking Water Regulations'' 
(Occurrence Methodology Document) (USEPA, 2003d). EPA selected its 16-
State cross-section to be as representative as possible of national 
contaminant occurrence. In EPA's judgment, these States provide a 
reasonable cross-section of agricultural and industrial pollution 
potential, as described in the Occurrence Methodology Document, and 
also provide geographic coverage of the United States. Therefore, EPA 
believes that the data assembled from these States is the most 
representative data currently available of national contaminant 
occurrence.
    The Agency did receive occurrence data from States other than those 
in its 16-State cross-section. However, many State data sets contained 
incomplete records (e.g., no water type or population records 
specified) or had other quality problems. Therefore, they were not 
included in the analyzed data set.
    b. Occurrence Analysis Methodology. One commenter noted that while 
the occurrence estimation methodology has several strengths, it also 
has a number of flaws. The commenter was concerned about the large 
proportion of non-detected observations in the occurrence data, and the 
difficulty of verifying the assumptions made by the Agency. The 
commenter agreed that EPA's occurrence analysis may represent a 
``decent'' estimate given the limitations of the data. The commenter 
also noted that the occurrence estimation methodology is premised on 
``subjective decisions or qualitative observations * * * rather than 
documented, statistically-based quantitative ones'' and would like to 
have seen alternate approaches used to provide confirmation of the 
estimates. In addition, the commenter questioned why the Agency used 
``modeled data sets to test the model rather than a standard 
statistical strategy of basing the model on a portion of the data set 
and using the remainder to test the model.''
    One commenter stated that the Stage 2 analysis (Bayesian analysis) 
was poorly described and that this conflicts with the transparency 
requirements of the 1996 SDWA Amendments. In addition, the commenter 
asked EPA to clarify how the occurrence data from other survey efforts, 
which are summarized in ``Occurrence Summary and Use Support Document 
for the Six-Year Review of Existing National Primary Drinking Water 
Regulations''

[[Page 42915]]

(Occurrence Summary Document) (USEPA, 2002f), were used to inform the 
modeling effort.
    EPA Response: EPA's occurrence model development work was 
significantly revised to reflect peer review comments prior to the 
March 2002 Occurrence Methodology Document (USEPA, 2002e) and the April 
17, 2002, Federal Register. The additional work involved the 
development of a detailed simulation study to evaluate the Bayesian 
model. EPA evaluated the performance of the Bayesian estimator and an 
alternative occurrence estimation approach, the Regression on Ordered 
Statistics (ROS) method, against synthetic data (i.e., data developed 
with known national contaminant occurrence distributions). This 
simulation study also enabled an explicit evaluation of the validity of 
the assumption of a log-normal distribution of the data.
    The simulation study was conducted using varying conditions of a 
correctly and incorrectly specified model, and synthetic data sets 
developed with high and low amounts of non-detected data. The study 
findings indicated that the Bayesian estimator performed well at 
estimating the distributions of contaminant concentration means 
(especially in the upper tails), performed better than the alternate 
approach (i.e., the ROS method), and accurately estimated the 
uncertainty of the distributional estimates. The Agency believes that 
this analysis supports the validity of EPA's analytical approach. The 
Bayesian model was tested against the ROS approach because the ROS 
method is an accepted drinking water contaminant occurrence estimation 
approach and was used to estimate occurrence for the recent arsenic 
rule. These findings were all included and described in the Six-Year 
Review's Occurrence Methodology Document.
    EPA has attempted to make its occurrence analysis as clear as 
possible. In response to the concerns raised by the peer reviewers, a 
less technical description of the occurrence estimation methodology, 
aimed at the general reader, was added to the main body of the 
document. A detailed description of the analysis, intended for readers 
with technical expertise, including the complete computer code used for 
model analysis, was incorporated into an appendix of the document. EPA 
agrees that its estimation methodology is complex, but also believes 
that it is as transparent as possible while still providing a 
technically accurate description of the Agency's analysis. The use of 
simple national occurrence (statistical) assessments is not possible at 
this time because there is no national database with a complete 
collection of regulated contaminant occurrence data. Thus, there is no 
ideal basis for comparison of national occurrence studies (i.e., the 
true system contaminant means and national distributions of contaminant 
occurrence are not, and cannot, be known). The validation approach 
suggested by the commenter (i.e., basing the model on a portion of the 
data set and using the remainder to test the model) is intended for a 
regression-type of model using observed system means to develop a model 
for system-specific predictions. This approach is not possible for the 
six-year occurrence assessments, since, to the best of EPA's knowledge, 
data on the true individual system contaminant mean concentrations and 
national distributions are not available.
    Regarding the other survey studies included in the Occurrence 
Summary Document, few, if any, provide the quantitative analytical 
results and national, representative coverage that would enable direct 
comparison to, or inclusion in, the Six-Year Review estimation analyses 
conducted with the 16-State cross-section occurrence data.
    c. Other Issues Related to the Occurrence Technical Review. One 
commenter stated that the Agency's current approach to estimate 
occurrence, employing a conservative methodology and making 
conservative simplifying assumptions in the absence of definitive data, 
was appropriate. On the other hand, the commenter argued that it was 
not appropriate for the Agency to conduct as massive a data collection 
and analysis project as was undertaken without clear quantitative 
objectives for the analysis identified a priori. The commenter noted 
that it was not apparent from either the April 17, 2002, Federal 
Register or the Occurrence Methodology Document (USEPA, 2002e) that the 
Agency undertook an effort to set performance objectives for the 
occurrence estimation.
    The commenter felt that the Occurrence Methodology Document does 
not allow the reader to determine if the data are well apportioned 
among the categories for which results are reported. They also noted 
that they were unable to find indications in the support document that 
such an analysis was undertaken in preparation for constructing the 
Bayesian model. The commenter stated that the support document does not 
include actual numeric counts or ranges of detected values and 
suggested that it would be useful to have this information by 
contaminant, State, system size category, and water type, as well as an 
explicit count of non-detects by this same matrix.
    EPA Response: There are several general approaches when undertaking 
and designing studies that require large amounts of data. As the 
commenter states, a priori data quality objectives are part of one 
research approach where study objectives (including technical 
statistical performance measures) are set, determinations are made on 
how to meet those objectives, and then the study is designed and 
implemented accordingly. This ideal was not practical for the national 
occurrence study conducted for the Six-Year Review because EPA did not 
have the resources to generate original data, and was thus dependent on 
the data that could be obtained from the States. The approach taken by 
the Six-Year Review was to gather a large amount of data that, in 
aggregate, was expected to be indicative of national contaminant 
occurrence, develop an occurrence estimation model that built upon what 
has been learned from recent regulatory development work, and then 
evaluate how good the resulting model estimates are.
    As discussed in section IV.A.6.b of today's action, the true 
national distributions of contaminant occurrence cannot be known. The 
16-State national cross-section data set used for the Six-Year Review 
is the largest compliance monitoring database for drinking water 
compiled by EPA to date. The database represents approximately 37 
percent of the total number of public water systems and 43 percent of 
the total population served by public water systems in the United 
States. External peer reviews assessed the approach for developing the 
national cross-section and its ``representativeness'' separately under 
the Chemical Monitoring Reform (CMR) project (in 1998/1999) (USEPA, 
1999c) and the Six-Year Review project (USEPA, 2002e), and provided 
generally favorable comments.
    The data management and cross-section development have been 
described in detail in the support documents for the CMR and the Six-
Year Review. Further tabulations of the data have been generated and 
presented, as the commenter requested, in the final Occurrence 
Methodology Document (USEPA, 2003d). This information includes the 
numbers and percentages of analytical detections and non-detections for 
each contaminant in each of the system size and source water type 
categories. Generally, because of the large amount of data and the 
manner in which the Bayesian model handles data, the distribution of 
observations across the various categories does not significantly 
affect EPA's estimates. The

[[Page 42916]]

number of analytical records differed by contaminant. EPA evaluated 
27,648 to 93,062 analytical records for the individual inorganic 
chemicals, 32,606 to 121,327 records for the synthetic organic 
chemicals, and 123,229 to 201,235 records for the volatile organic 
chemicals. Most importantly, the Stage 2 occurrence model also 
quantifies the uncertainty of the estimates in the different categories 
of system size and source water type. Hence, the statistical 
significance of differences in occurrence between the categories can be 
easily assessed. However, the Agency believes it is more appropriate to 
consider the universe of potentially affected systems within the 16-
State cross-section, rather than individual system categories, when 
making its revise/not revise decisions as part of the Six-Year Review 
process.
7. Consideration of Available Economic Information
    Some commenters stated that, while the Agency's review of NPDWRs 
was generally consistent with NDWAC recommendations to EPA (NDWAC, 
2000), it is not clear how the Agency took economic factors into 
account.
    EPA Response: An EPA memorandum, dated March 18, 2002, describes 
the Agency's qualitative evaluation of economic factors (USEPA, 2002c). 
This memorandum was cited in the April 17, 2002, Federal Register and 
is available in the docket for the Six-Year Review (Docket No. OW-2002-
0012). It notes that detailed economic analyses were not deemed by the 
Agency to be necessary to support its decisions of whether or not to 
revise a particular NPDWR. Rather, a qualitative assessment, based on 
the extent of occurrence of a contaminant at the MCL, as well as at 
alternative levels, was undertaken to inform the Agency's judgment 
about whether possible changes to an MCL offered a meaningful 
opportunity for health risk reduction and/or cost-savings to public 
water systems and their customers. EPA has conducted this assessment 
for 15 of the chemical NPDWRs for which the Agency had determined that 
a potential health or technological basis may exist for considering a 
revision to the MCLG/MCL.\2\ EPA compared the estimated occurrence and 
exposure values at the current MCL and at potentially revised 
regulatory level(s). For 14 of these chemical NPDWRs, the Agency's 
assessment showed that the differences were small. In EPA's judgment, 
these differences are unlikely to provide a meaningful opportunity for 
health risk reduction or cost-savings to public water systems and their 
customers. After consideration of these factors, EPA decided that any 
revision would be a low priority activity for the Agency, and, thus, 
not appropriate to revise at this time because of: Competing workload 
priorities; the administrative costs associated with rule making; and 
the burden on States and the regulated community to implement any 
regulatory change that resulted. In the case of dichloromethane, the 
Agency did not have sufficient data to recalculate the PQL to support 
any potential regulatory revision and thus placed it in the data gaps 
category.\3\
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    \2\ These 15 chemical NPDWRs are: Benzene; beryllium; chlordane; 
1,2-dibromo-3-chloroproppane dichloromethane; 1,1-dichloroethylene; 
1,2-dichloropropane; heptachlor; heptachlor, epoxide; 
hexachlorobenzene; lindane; oxamyl; picloram; toxaphene; and 1,1,2-
trichloroethane.
    \3\ The other three NPDWRs in the data gaps category, chromium, 
fluorida, and lead, were placed there for reasons other than 
occurrence and economic considerations. Chrominum is in the data 
gaps category because of the studies being conducted by the National 
Toxicology Program studies. Fluoride is in the data gaps category 
pending a National Academy of Sciences update of the health risk 
assessment and review of the RSC assumptions. Lead is in the data 
gaps category based on consideration of public comments (see section 
IV.B.13 of today's action).
---------------------------------------------------------------------------

B. What Comments or New Information Did EPA Receive on Chemical 
Contaminant-Specific Issues?

1. Alachlor
    One commenter stated that the Office of Pesticide Programs (OPP) 
found that the chloroacetanilide pesticides (acetochlor, alachlor, and 
butachlor) should be considered as a group of chemicals having a common 
mechanism of toxicity due to their ability to cause nasal turbinate 
tumors. The commenter believes EPA therefore should adopt a strong 
total chloroacetanilide pesticide standard that would strengthen the 
current standards.
    EPA Response: Butachlor and acetochlor do not presently have an 
NPDWR and thus, are not included in the Six-Year Review. However, 
acetochlor is included on the Contaminant Candidate List (CCL) and may 
in the future be considered as a candidate for regulation. Alachlor is 
a regulated drinking water contaminant and is included in the Six-Year 
Review. It is currently undergoing a risk assessment and, therefore, 
the Agency believes that revision of the NPDWR is not appropriate at 
this time.
    If the Agency decides to regulate either acetochlor or butachlor in 
the future, EPA may consider regulating them as a group, including 
alachlor, following a cumulative risk assessment process for pesticides 
that have a common mechanism of toxicity. It would be premature to 
propose a total chloroacetanilide pesticide standard until a cumulative 
risk assessment is completed because this analysis could impact the 
Agency's evaluation of specific members of this group, or the group as 
a whole.
2. Antimony
    a. Health Effects. A number of commenters have suggested that the 
current MCLG and MCL of 0.006 milligrams per liter (mg/L) for antimony 
need to be revised. Some of the reasons given were:
    [sbull] The study used to derive the current MCLG (Schroeder et 
al.,1970) is not consistent with current good laboratory practice 
guidelines and there are several newer studies of antimony toxicity 
that should be considered in deriving a new reference dose (RfD).
    [sbull] Animals used in the Schroeder et al., 1970 study had a 
viral infection. To compensate for this infection, adjustments were 
made to the size of the animal groups in an attempt to salvage the 
data.
    [sbull] The antimony compound used in the Schroeder et al., 1970 
study was potassium antimony tartrate, the most water soluble and toxic 
form of antimony. Antimony found in drinking water is likely to be in 
the form of less toxic trivalent and pentavalent antimony species. 
Therefore, basing the MCLG on the most toxic species of antimony 
(potassium antimony tartrate) is likely to overestimate the risk posed 
by antimony in drinking water.
    EPA Response: EPA agrees that the MCLG and MCL for antimony may 
need to be re-evaluated. EPA is in the process of developing a new 
health risk assessment for antimony, taking into consideration new 
studies that have become available on the toxicity of antimony. EPA 
expects to complete the health risk assessment for antimony in the 
2003-2004 time frame (68 FR 5870, February 5, 2003 (USEPA, 2003h)). As 
a result of the ongoing health risk assessment, a revision to the 
antimony standard is not appropriate at this time, and antimony will be 
re-evaluated as part of the next Six-Year Review process.
    b. Treatment and Implementation Issues. Several commenters 
questioned the appropriateness of the antimony MCL, and the 
effectiveness of using the EPA-designated best available technologies 
(BATs) to meet the antimony MCL. A few small systems in Utah have 
levels of antimony in water at or above the MCL value of 0.006 mg/L. 
These systems were granted

[[Page 42917]]

exemptions contingent upon testing and installation of treatment by 
March 2004.
    These systems are investigating treatment options for the removal 
of antimony from their source water. Commenters submitted supporting 
data documenting the results of their testing and cost analyses. 
According to commenters, on-site testing indicated that the designated 
BATs (i.e., reverse osmosis and coagulation/filtration) and most of the 
other tested treatments were ineffective and/or prohibitively expensive 
due to: raw water quality concerns; water conservation needs; current 
costs for water production; and other concerns, such as waste water 
management. However, commenters did identify treatment options that may 
be feasible, but these may require further investigation prior to full 
scale use.
    EPA Response: As discussed in the April 17, 2002, Federal Register 
and as noted in the previous response in section IV.B.2.a, EPA does not 
believe it is appropriate to consider revisions to the NPDWR for 
antimony at this time because of the ongoing health risk assessment (67 
FR 19030 at 19051 (USEPA, 2002g)).
    When EPA initially promulgated the antimony NPDWR in 1992, the 
Agency estimated that 200 public water systems would be affected 
(USEPA, 1992). EPA recognizes that implementation of this standard may 
present challenges for a few localities. Although the use of the 
designated BATs for antimony may not be appropriate in some cases, as 
long as systems comply with the MCL, they are not limited to these 
technologies.
    EPA believes that the treatment data generated by the commenters 
may be valuable and may provide insight into potential alternative 
treatment technologies. The Agency has revised the document, ``Water 
Treatment Technology Feasibility Support Document for Chemical 
Contaminants; In support of EPA Six-Year Review of National Primary 
Drinking Water Regulations'' (Treatment Feasibility Document) (USEPA, 
2003g) to refer to these preliminary test data as they may be 
applicable to the development of potential new treatment technologies 
for the removal of antimony and other contaminants.
3. Atrazine
    a. Health Effects. Several commenters addressed the EPA decision 
not to consider revision of the MCL for atrazine at this time. Some of 
these commenters stated that EPA should use the risk assessment, 
released by OPP in May 2002, as a basis for reconsidering the atrazine 
NPDWR. One of the commenters noted that the 2002 risk assessment is 
based on reproductive and developmental endpoints which represents a 
change from the toxicity endpoint that formed the basis of the current 
MCLG. Two commenters stated that the MCL for atrazine should be revised 
upward because of the results of the 2002 OPP risk assessment in which 
the RfD increased and the cancer classification changed from ``possible 
human carcinogen'' to ``not likely to be a human carcinogen.'' The 
commenters stated that the change in the cancer assessment implies 
elimination of the additional 10-fold risk management factor used in 
1991 to derive the MCLG/MCL for atrazine. Another commenter stated that 
atrazine should be regulated using a non-linear approach which 
recognizes that there is a level at which no known health effects occur 
and that these findings must be part of the new MCL.
    Conversely, another commenter stated that there is substantial new 
evidence from epidemiological and occupational studies that atrazine 
poses a serious cancer risk, and that it is an endocrine disruptor at 
low levels. The commenter believes EPA should adopt a revised atrazine 
and total triazine standard lower than (i.e., more stringent than) the 
current 0.003 mg/L standard for atrazine.
    A commenter also urged the Agency to:
    [sbull] Provide a definitive timetable for review of the standard;
    [sbull] Outline a preliminary scope for its review of the standard; 
and
    [sbull] State the underlying premise for the scope of the review.
    Other commenters stated that the existing NPDWR only regulates the 
parent compound atrazine, and that a revised NPDWR should include the 
chloro-metabolite degradants (i.e., diaminochlorotriazine (DACT), 
desethyl atrazine (DEA), and desisopropyl atrazine (DIA)). These 
commenters believe that inclusion of the chloro-metabolites would 
strengthen compliance monitoring programs for public water systems 
under SDWA and thereby strengthen public health protection. They stated 
that a regulation for atrazine and the chloro-metabolites should be 
developed and promulgated within the next 12 to 18 months. Another 
commenter stated that since the Agency has found that atrazine, 
simazine, propazine, and the degradants DACT, DEA, and DIA have a 
common mechanism of toxicity, these should be regulated in a total 
triazine regulation.
    EPA Response: EPA does not believe it is appropriate to consider 
revisions to the NPDWR for atrazine at this time because the revised 
risk assessment has not been finalized. For purposes of the Six-Year 
Review protocol, EPA considers a risk assessment final when an Interim 
Reregistration Eligibility Decision (IRED), Reregistration Eligibility 
Decision (RED), and/or IRIS assessments are complete.\4\ Even though an 
IRED for atrazine was signed on January 31, 2003, an amended IRED is 
scheduled to be released in October 2003 which will include a 
Scientific Advisory Panel (SAP) peer review of new data related to 
health effects. Based upon the outcome of the SAP review, the October 
2003 IRED may include additional information that could impact a 
revise/not revise decision. Therefore, EPA does not believe it is 
appropriate to consider possible revisions to the NPDWR at this time.
---------------------------------------------------------------------------

    \4\ The IRED is an intermediate decision for an individual 
pesticide that does not take into account cumulative risk issues for 
pesticides with a common mode of action. The RED does include 
cumulative risk. If an IRIS assessment is also in process when the 
IRED or RED is signed, EPA will make a case-by-case decision on 
whether to wait for the IRIS assessment before considering possible 
revisions to the NPDWR.
---------------------------------------------------------------------------

    In reviewing the atrazine regulation, EPA will apply an approach 
consistent with the protocol used for the current review. The Agency 
will consider the same key elements (i.e., health effects review, 
technology review, other regulatory revisions review, and, if 
appropriate, occurrence/exposure analyses and consideration of 
available economic information) and apply the same basic decision tree 
for making a revise/not revise decision.
    To address the issue of regulating the triazines as a group, the 
Agency is evaluating the unregulated triazines as part of the CCL 
process. When the risk assessment is completed for atrazine, the Agency 
will consider whether or not there are compelling reasons for 
considering a revision to the atrazine regulation or to wait until the 
risk assessment for the triazines, which considers issues of cumulative 
risk, is finalized. EPA will use the CCL regulatory determination 
process in deciding whether the triazines should be regulated as a 
group.
    b. Costs of Treatment. Commenters stated that the costs associated 
with not revising the MCL are great. These commenters are concerned 
that State agencies will be required to develop total maximum daily 
loads (TMDLs) based on 303(d) \5\ listings resulting from

[[Page 42918]]

an outdated MCL which creates a burden on State and local government, 
its citizens, and diverts limited resources away from programs that 
provide real benefits. Some commenters also stated that the treatment 
costs to hundreds of community water systems are considerable. One 
commenter also stated that these are real dollars that would otherwise 
be available for emergency services, education, nutrition programs, and 
other vital programs that are the responsibilities of local and State 
agencies.
---------------------------------------------------------------------------

    \5\ Section 303(d) of the Clean Water Act and the implementing 
regulations (40 CFR 130.7) require States to develop TMDLs for 
waters where required point and nonpoint source pollution controls 
are not stringent enough to attain or maintain compliance with State 
water quality standards after the application of technology-based 
and other required controls. A TMDL establishes the maximum amount 
of a pollutant that may be introduced into a waterbody while still 
ensuring attainment and maintenance of water quality standards.
---------------------------------------------------------------------------

    EPA Response: As stated in the previous response in section 
IV.B.3.a, EPA does not believe it is appropriate to revise the NPDWR 
for atrazine at this time because the risk assessment is not yet final. 
If EPA decides to revise the NPDWR for atrazine, economic factors, 
including feasibility and an assessment of costs and benefits, will be 
taken into consideration for the drinking water program.
4. Beryllium
    Two commenters believed that the current drinking water standard 
for beryllium is more stringent than necessary for the protection of 
public health and felt that EPA should adopt a higher value for the 
beryllium standard. These commenters disagreed with EPA on the use of 
an uncertainty factor of 300 in deriving the 1998 RfD. The commenters 
stated the use of uncertainty factors of 3 for database uncertainty, 10 
for extrapolating data from a dog study to humans, and 10 for 
intraspecies variation is inappropriate. The commenters stated that EPA 
has the authority to raise the current drinking water standards for 
beryllium based on new information that allows for a smaller margin of 
safety than the one used by EPA. The commenter felt that the current 
standard for beryllium is ``lower than necessary to protect the public 
from beryllium toxicity and results in clean-up standards that are 
lower than naturally occurring level of beryllium in water sources and 
soils.'' This commenter also expressed concern that the local 
application of the Federal drinking water standard to private wells in 
some cases caused undue concerns among users of those wells.
    EPA Response: One of the purposes of the Six-Year Review is to 
determine if the MCL of a chemical should be changed based on a revised 
RfD or cancer classification. Analytical methods and treatment 
technologies are considered, as well as occurrence in public water 
systems. The RfD for beryllium was revised in 1998 based on extensive 
Agency internal and external reviews, and is unlikely to be revised in 
the absence of new data. The 1998 assessment also provided separate 
cancer classification for inhalation and oral exposures (USEPA, 1998). 
In the revised assessment, the carcinogenicity of beryllium by the 
inhalation route was described as ``likely,'' while that by the oral 
route of exposure ``cannot be determined.'' As discussed in the April 
17, 2002, Federal Register, the Agency considered the occurrence of 
beryllium at both potentially higher and lower regulatory levels. EPA 
concluded that a revision to the NPDWR would not result in a meaningful 
opportunity for health risk reduction or cost-savings to public water 
systems and their customers. As a result, revision of this NPDWR is a 
low priority action for the Agency and is not appropriate at this time.
    The goal of drinking water standards is to protect public health. 
Therefore, it does not matter whether the source of contamination is 
naturally-occurring or man-made. While EPA appreciates the information 
on private wells, the SDWA requirements do not apply to private wells 
(i.e., wells that are not part of a ``public water system''). The costs 
and benefits of a drinking water standard are assessed only with regard 
to the impacts on public water systems and their customers.
5. Carbofuran
    Some commenters mentioned that the Agency concluded that N-methyl 
carbamates, including carbofuran, should be considered as a class 
because they have a common mechanism of toxicity. Therefore, they 
believe EPA should issue a stronger standard for total N-methyl 
carbamates, including carbofuran, which would be more stringent than 
the current carbofuran standard of 0.04 mg/L.
    EPA Response: EPA is re-evaluating the toxicity of carbofuran. 
However, a final assessment has not been issued by EPA. The Agency 
considers N-methyl carbamate pesticides as a group of chemicals having 
a common mechanism of toxicity due to their ability to inhibit 
acetylcholinesterase. However, it is not appropriate to revise the 
NPDWR for carbofuran at this time because the Agency has not yet 
completed the final health risk assessment for carbofuran or the other 
N-methyl carbamates.
6. Chromium
    One commenter requested that EPA move quickly in making a revise/
not revise determination once the new data on chromium become available 
from the National Toxicology Program (NTP) studies of the health 
effects of chromium VI.
    EPA Response: The NTP studies that the commenter refers to should 
be available before the end of the next Six-Year Review cycle. 
Meanwhile, EPA is continuing to follow the progress of NTP in 
conducting subchronic and chronic studies of chromium VI.\6\ NTP made 
the data from the subchronic portion of the study available to the 
public in June 2002 (NTP, 2002). A peer review meeting was held at NTP 
on July 24, 2002. EPA will examine the peer review report covering the 
subchronic data once it becomes available. Once the subchronic and 
chronic studies are completed, the health effects data will be 
evaluated with regard to their impact on the present RfD and cancer 
assessment, and integrated with the occurrence and analytical method 
data before making a new revise/not revise decision.
---------------------------------------------------------------------------

    \6\ Since NTP is posting its progress on its internet site 
http://ntp-server.niehs.nih.gov/htdocs/Studies/HexChromium/hexchromiumpg.html, EPA and the public will be able to evaluate the 
new data relative to the existing EPA assessment for chromium VI as 
it is released.
---------------------------------------------------------------------------

7. 1,1-Dichloroethylene
    In the April 17, 2002, Federal Register, the Agency preliminarily 
placed 1,1-dichloroethylene in the no revision category because a 
health risk assessment was pending at the time of publication. Since 
the publication of the April 17, 2002, Federal Register, the Agency has 
finalized the risk assessment for 1,1-dichloroethylene. The remaining 
paragraphs in this section include a brief background discussion about 
the original promulgation of the 1,1-dichloroethylene NPDWR, the 
results of the appropriate six-year technical reviews and the Agency's 
revise/not revise decision.
    a. Background. EPA published the current NPDWR for 1,1-
dichloroethylene on July 8, 1987 (52 FR 25690 (USEPA, 1987)). The NPDWR 
established an MCLG and an MCL of 0.007 mg/L. The Agency based the MCLG 
on an RfD of 0.009 milligram per kilogram of body weight per day (mg/
kg/day) and a cancer classification of C, possible human carcinogen.
    b. Technical Reviews. EPA updated the risk assessment for 1,1-
dichloroethylene on August 13, 2002 (USEPA, 2002i). The new risk 
assessment established an RfD of 0.046 mg/kg/day, based on the same 
toxicological study as that of the MCLG, but using an uncertainty 
factor of 100

[[Page 42919]]

instead of 1,000, and using benchmark dose modeling for the dose-
response analysis. Under the 1986 cancer guidelines (51 FR 33992, 
September 24, 1986 (USEPA, 1986)), 1,1-dichloroethylene was assigned to 
Group C, possible human carcinogen. Under the draft revised 
``Guidelines for Carcinogen Risk Assessment'' (USEPA, 1999a), the data 
for 1,1-dichloroethylene were considered inadequate for an assessment 
of human carcinogenic potential by the oral route.
    Based on the change in RfD for 1,1-dichloroethylene, using a 20 
percent RSC and a 10-fold risk management factor for possible 
carcinogenicity, EPA used 0.03 mg/L as a level for evaluating the 
occurrence data. Without the use of the 10-fold risk management factor, 
EPA also used 0.3 mg/L as a level for evaluating the occurrence data.
    Analytical or treatment feasibility do not pose any limitations for 
the current MCL and would not be a limiting factor at the 0.03 mg/L or 
the 0.3 mg/L level (USEPA, 2002a; USEPA, 2003g). The Agency's review of 
possible ``other regulatory revisions'' did not identify any issues 
that are specific to 1,1-dichloroethylene (USEPA, 2003b).
    EPA evaluated the results of the occurrence and exposure analyses 
for 1,1-dichloroethylene to determine whether possible changes to the 
standard would be likely to result in a meaningful opportunity for 
cost-savings to public water systems and their customers (USEPA, 
2003d). Table IV-1 shows the results of the detailed occurrence and 
exposure analysis based on the 16-State cross-section for the current 
MCL (0.007 mg/L), and for two higher levels (0.03 mg/L and 0.3 mg/L). 
Based on the detailed analysis, it appears that 1,1-dichloroethylene is 
unlikely to occur at concentrations above 0.007 mg/L in the States used 
for the cross-section.
BILLING CODE 6560-50-P

[[Page 42920]]

[GRAPHIC] [TIFF OMITTED] TN18JY03.071

BILLING CODE 6560-50-C

[[Page 42921]]

    The results of the detailed occurrence and exposure analysis 
indicate that less than 0.02 percent of the 19,101 systems sampled in 
the 16-State cross-section, and less than 0.02 percent of the 
population served by those 19,101 systems might be affected if EPA were 
to consider levels as high as 0.03 mg/L to 0.3 mg/L. The current BATs 
and small system compliance technology for 1,1-dichloroethylene have 
other beneficial effects (e.g., reduction of other co-occurring 
contaminants, or other common impurities) in addition to 1,1-
dichloroethylene removal. Therefore, if EPA were to consider any of 
these higher levels, the Agency does not know how many of these public 
water systems that are currently treating to comply with the current 
MCL of 0.007 mg/L would be likely to discontinue treatment that is 
already in place (USEPA, 2002c; USEPA, 2003g).
    c. Current Decision. Although there are new health effects data 
that might support calculation of a less stringent standard for 1,1-
dichloroethylene, EPA does not believe a revision to the NPDWR for 1,1-
dichloroethylene is appropriate at this time. In making this decision, 
the Agency considered whether any potential revision to the 1,1-
dichloroethylene NPDWR is likely to provide a meaningful opportunity 
for cost-savings to public water systems and their customers. After 
consideration of this factor, EPA has decided that any revision to 1,1-
dichloroethylene would be a low priority activity for the Agency, and, 
thus, is not appropriate to revise at this time because of:
    [sbull] Competing workload priorities;
    [sbull] The administrative costs associated with rulemaking; and
    [sbull] The burden on States and the regulated community to 
implement any regulatory change that resulted.
8. Dichloromethane
    One commenter stated that it may be difficult to lower the PQL for 
dichloromethane below the range of 0.001 to 0.002 mg/L since it is 
required in a number of EPA methods and therefore is a common 
laboratory contaminant. Because it is a common laboratory contaminant, 
the commenter stated that using the MDL for 524.2 and 502.2 does not 
constitute a reasonable basis for assuming that the PQL can be lower. 
The commenter stated that none of the existing WS studies had spike 
samples this low and, in addition, the occurrence data may have been 
compromised due to laboratory contamination.
    EPA Response: The basis for EPA indicating that a lower PQL ``may 
exist'' was due to the fact that laboratories had greater than 95 
percent laboratory passing rates using a +/-40 percent acceptance 
window at ``known'' spike concentrations close to current MCL of 0.005 
mg/L. If laboratory contamination due to dichloromethane were a 
problem, such high passing rates at this value would not be expected. 
The MDLs for 524.2 and 502.2 were only used with the 10 times MDL 
multiplier to estimate what the lower value could be. However, EPA does 
agree that, at this time, the Agency does not have sufficient data to 
recalculate the PQL for dichloromethane and for this reason, the Agency 
placed it in the data gap category.
    Regarding the occurrence issue, EPA has no data to suggest that 
high occurrence values were due to false positives from laboratory 
contamination and the Agency is proceeding on the assumption that State 
data are accurate unless there is information to the contrary. If 
laboratory contamination due to dichloromethane does exist, 
laboratories should be able to identify and discern a contamination 
issue if they are running laboratory blanks.
9. Di(2-ethylhexyl)adipate (DEHA)
    One commenter submitted detailed comments regarding di(2-
ethylhexyl)adipate (DEHA). The commenter believed that EPA should 
consider removing the regulation for DEHA and provided the following 
reasons:
    [sbull] The regulation of DEHA in drinking water does not provide 
any meaningful reduction in the health risk to humans because it is 
unlikely to cause adverse effects to humans, including reproductive 
effects, except at very high doses which cannot be attained in drinking 
water, due to the low water solubility of DEHA.
    [sbull] The weight of evidence indicates that the peroxisome 
proliferation mechanism of DEHA rodent carcinogenicity is not relevant 
to humans. Thus, the MCLG for DEHA should not include an additional 10-
fold risk management factor for possible carcinogenicity.
    [sbull] The legislative history of the 1996 SDWA indicates that 
Congress envisioned circumstances where relaxation of an MCL would 
provide the same level of health protection as the existing regulation. 
Accordingly, if DEHA cannot be deregulated, the commenter believes the 
MCLG and MCL should be increased.
    EPA Response: DEHA was regulated in 1992. Since that time, new 
studies have become available on the toxicity of DEHA and its 
metabolites. For this reason, EPA decided to initiate a new health risk 
assessment of DEHA (67 FR 1212, January 9, 2002 (USEPA, 2002a)). The 
assessment will include examination of the studies on which the current 
NPDWR is based, as well as an evaluation of the data provided by this 
commenter and new studies that have become available since DEHA was 
regulated. This health risk assessment is planned for completion in the 
2003-2004 time frame (68 FR 5870, February 5, 2003 (USEPA, 2003h)) and 
is expected to include development of an RfD for non-cancer health 
effects, as well as an assessment of potential carcinogenicity from 
oral exposure. At this time, it is premature to predict the outcome of 
the Agency's assessment. Thus, as discussed in section IV.A.2.a of 
today's action, the Agency believes that revision to the NPDWR for DEHA 
is not appropriate at this time. EPA will determine in the future if 
revision of the MCLG/MCL is warranted. Any revision to the MCLG/MCL 
will also take into consideration all the new information, including 
the water solubility of DEHA under various environmental conditions.
    As stated by the commenter, the legislative history of the 1996 
SDWA Amendments supports EPA's interpretation that the Agency could 
increase an MCLG and MCL as long as the relaxed standard does not 
lessen the level of public health protection. However, EPA does not 
believe, at the present time, that it can demonstrate that deregulating 
DEHA would maintain the current level of public health protection (see 
section IV.A.1.c of today's action).
10. Di(2-ethylhexyl)phthalate (DEHP)
    The same commenter who submitted comments on DEHA also submitted 
detailed comments regarding di(2-ethylhexyl)phthalate (DEHP). The 
commenter felt that EPA should consider removing the regulation for 
DEHP for a variety of reasons, including the following:
    [sbull] The regulation of DEHP in drinking water does not provide 
any meaningful reduction in the health risk to humans.
    [sbull] The weight of the evidence indicates that the mode of 
action through which DEHP causes cancer in rodents is not relevant to 
humans and, thus, the MCLG for DEHP should not be zero. Any MCLG for 
DEHP should be based on a threshold endpoint and not on cancer. The 
commenter cited the February 2000 International Agency for Research on 
Cancer reclassification of DEHP from Group 2B (possibly carcinogenic to 
humans) to Group 3 (not classifiable as to its carcinogenicity to 
humans) as justification for recommending that EPA also reconsider its 
cancer classification.

[[Page 42922]]

    [sbull] The solubility of DEHP in drinking water is well below any 
concentrations that would pose a risk to humans.
    [sbull] If DEHP were to be considered for regulation under the 
statutory requirements of the 1996 SDWA, it would not be regulated.
    [sbull] The legislative history of the 1996 SDWA indicates that 
Congress envisioned circumstances where relaxation of an MCL would 
provide the same level of health protection as the existing regulation. 
Accordingly, the commenter believes consideration should be given to 
increasing the MCLG for DEHP based on the new health effects data.
    [sbull] Reproductive effects from DEHP as observed in rodents do 
not appear to be relevant for primates and the doses that are 
associated with effects in animals are well above those that would be 
experienced for humans exposed through drinking water because of 
solubility limitations. The commenter also highlighted the findings of 
the NTP Center for the Evaluation of Risk to Human Reproduction that 
there was ``minimal concern for reproductive or developmental toxicity 
for the general population, based on estimates of total exposure to 
DEHP.''
    EPA Response: Revision of the NPDWR for DEHP is not appropriate at 
this time because an Agency health risk assessment is currently in 
process. The assessment is anticipated to be completed in the 2003-2004 
time frame (68 FR 5870, February 5, 2003 (USEPA, 2003h)). Advances in 
understanding differences between the primate and rodent response to 
DEHP and the body of toxicological data that have become available in 
the past decade motivated the Agency's re-examination of DEHP and will 
be fully considered in the reassessment.
    Once the Agency assessment is completed, EPA will consider the 
findings and will determine if there is a compelling reason to review 
the DEHP NPDWR prior to the next Six-Year Review cycle. As discussed in 
sections IV.A.1.b and IV.A.2.a of today's action, ``revise'' versus 
``not revise'' decisions under the Six-Year Review take into 
consideration occurrence, advances in analytical methods, treatment 
technologies, available economic information, and other factors.
    As stated by the commenter, the legislative history of the 1996 
SDWA Amendments supports EPA's interpretation that the Agency could 
increase an MCLG and MCL as long as the relaxed standard does not 
lessen the level of public health protection. However, EPA does not 
believe, at the present time, that it can demonstrate that deregulating 
DEHP would maintain the current level of public health protection (see 
section IV.A.1.c of today's action).
11. Fluoride
    EPA received three comments on the Agency's decision to place 
fluoride in the data gap category while the National Academy of 
Sciences (NAS) examines the toxicological and RSC data published over 
the last decade. Two of the commenters supported EPA's decision. One of 
these requested that the NAS concentrate its review on all of the data 
on the toxicology of fluoride and not just data on the critical 
skeletal effects. A third commenter requested that EPA not lower the 
MCL for fluoride from 4 mg/L to 2 mg/L and supported the 1986 EPA 
decision that dental fluorosis is a cosmetic effect rather than an 
adverse health effect. The commenter stated that the Public Health 
Service (PHS) recommended fluoridation level to be used at schools is 3 
mg/L. The commenter also stated that if EPA were to lower the MCL, then 
schools that are currently fluoridating might have a conflict with the 
PHS recommendations and the EPA MCL.
    EPA Response: The National Research Council (NRC) of the NAS has 
agreed to review the toxicological data on fluoride that have been 
published since it completed the 1993 study of ``Health Effects of 
Ingested Fluoride'' (NRC, 1993), and to examine the data on relative 
fluoride exposure from drinking water compared to fluoride exposure 
from the diet and fluoride-containing dental products. Although the 
Agency indicated in the April 17, 2002, Federal Register that new data 
on bone effects were a reason for initiating the data review (because 
bone effects were the basis of the present MCLG), the NAS review will 
look at the new toxicological data for all endpoints. It is anticipated 
that the NAS review will take about two years to complete. Because of 
this pending review, revision of the NPDWR for fluoride is not 
appropriate at this time.
    It is therefore premature to make any judgment regarding the NAS 
findings and whether or not they may lead to a consideration of a 
change in the MCL. However, PHS recommendations for school fluoridation 
programs are designed to provide the benefits of fluoridation without 
increasing the risk for dental fluorosis. The PHS recommends school 
water fluoridation only if:
    [sbull] The school has its own source of water;
    [sbull] The school is not connected to a community water system;
    [sbull] More than 25 percent of students are not served by a public 
water system that provides water at levels adequate to protect against 
dental caries; and
    [sbull] The students served are kindergarten age or greater.
12. Glyphosate
    Two commenters made the statement that, despite continued use of 
glyphosate in pesticide applications, available data and the Agency's 
occurrence analysis, which includes a prediction of frequency of 
occurrence at levels below detection, indicate that glyphosate is not 
observed in compliance monitoring. One of these commenters stated that 
the occurrence appeared to be rare (less than 0.1 percent) at 
concentrations 1,000 times lower than the MCL. In addition, according 
to the commenters, the cost of analyzing for glyphosate is expensive, 
since it is a single analyte analysis. Accordingly, the commenters 
wanted EPA to reconsider the glyphosate standard taking costs and 
benefits into account. The commenters felt that the data may indicate 
that a glyphosate standard is inappropriate and does not result in any 
additional public health protection. Therefore, the commenters 
recommended EPA pursue data gaps that the Agency would need to fill in 
order to demonstrate that eliminating the glyphosate standard would not 
lower public health protection.
    EPA Response: EPA is conducting an Agency risk assessment for 
glyphosate that will update the 1993 OPP assessment. As a part of this 
process, EPA is considering all the data that have been published or 
submitted to EPA since the completion of the RED in 1993 (USEPA, 1993). 
Accordingly, revision of the glyphosate NPDWR is not appropriate at 
this time due to the pending Agency assessment.
    EPA recognizes that some utilities feel that the analysis of 
glyphosate in drinking water is expensive and that this should be taken 
into consideration with respect to cost and benefits. This will be 
considered when EPA evaluates glyphosate in the next review cycle 
(unless there is a compelling reason to evaluate glyphosate on an 
accelerated schedule). For the reasons stated in section IV.A.1.c of 
today's action, EPA does not believe it is appropriate to consider 
deregulation of glyphosate at this time.
13. Lead and Copper
    a. Research Needs. Three commenters acknowledged the Agency's 
January 2000 revisions to the Lead and Copper Rule (LCR) but stated 
that the Agency should continue to consider how to

[[Page 42923]]

make the LCR easier to implement. In particular, they recommended that 
the following three LCR-related research areas be incorporated into 
EPA's overall research strategy:
    1. How well LCR monitoring results correlate to actual exposure and 
the effectiveness of the rule in protecting public health.
    2. Whether there is a correlation between water quality at indoor 
and outdoor taps.
    3. What effect the ban on lead in fixtures has had on lead levels 
and whether changes need to be made based on this ban.
    The commenters explained their rationale for recommending that the 
Agency determine if a correlation could be established between indoor 
and outdoor water quality. They stated that a major weakness of the LCR 
is that sample integrity may be compromised by allowing customers to 
collect water samples. If the Agency could establish such a 
correlation, the LCR could be revised to allow water system operators 
to collect samples from outdoor taps; thereby removing the need for 
customer-collected sampling.
    EPA Response: EPA recognizes that the LCR is a challenging rule 
that requires difficult solutions to implement, but continues to 
believe that the public health objective addressed by the rule is as 
important and essential today as it was when the rule was first 
promulgated. Since the Agency promulgated the revisions to the LCR in 
January 2000 (65 FR 1950, January 12, 2000 (USEPA, 2000)), the Agency 
has received no significant new information that would support a 
revision. However, the Agency recognizes that more research would be 
useful to obtain additional information that could be utilized to 
address some of the issues associated with the implementation of this 
rule. For this reason, EPA has revised its rationale for not revising 
the NPDWR for lead and placed it in the data gaps category. Although 
the Agency continues to believe that the NPDWR for copper belongs in 
the risk assessment in process category at the present time, EPA will 
also consider copper-related risk management and implementation issues 
as a part of any LCR-related research plans. The Agency is committed to 
working with stakeholders to support and coordinate identification and 
prioritization of LCR-related research needs. Until this research is 
completed, EPA believes it is premature to consider revisions to the 
LCR; as a result, revision of the LCR is not appropriate at this time.
    The Agency believes that understanding the possible correlation 
between monitoring results and actual rates of exposure and public 
health protection is a valid issue. However, EPA recognized during the 
initial regulatory development of the LCR that a significant effort 
would be necessary to provide a statistically valid number and 
frequency of samples for an exposure assessment. The Agency thus 
adopted an alternative approach which specified a monitoring scheme 
that sought to ``* * * assure that systems are performing `optimal 
corrosion control' in part by requiring systems to conduct 
comprehensive tap sampling at homes specifically targeted for their 
potential to contain elevated levels of lead and copper'' (56 FR 26460 
at 26514, June 7, 1991 (USEPA, 1991b)). One issue in assessing exposure 
reduction resulting from the LCR is a determination of an exposure 
baseline. EPA does not have a lot of data against which to measure 
changes in exposure that have occurred as a result of rule 
implementation. For these reasons, EPA believes that there is still 
insufficient information to change the basic monitoring approach 
adopted in the original rule, but recognizes that additional research 
may be useful.
    Research on whether a correlation exists between the water quality 
at indoor taps and water quality at outdoor taps is a very complex 
issue. Several variables potentially affect whether a reliable 
correlation exists between indoor and outdoor taps. These variables 
include: standing time within the system; contact time with the 
building plumbing; and the content of the interior plumbing. These 
variables, coupled with the fact that lead levels from building-to-
building can be highly site-specific, make a correlation between indoor 
and outdoor taps difficult to establish. EPA continues to believe that 
focusing on the point of delivery to the customer most closely links 
the data collected to the water quality consumed by the customer.
    EPA recognizes the commenter's concerns regarding the integrity of 
samples collected by drinking water customers. To date, however, the 
Agency has not been able to identify an acceptable alternative to 
monitoring at the consumer's tap that can produce results equivalent to 
those obtained at the point of consumption in terms of ensuring 
adequate public health protection.
    Regarding the commenter's third recommendation, EPA will consider 
this research need as part of the Agency's overall drinking water 
research planning process.
    b. Relaxing the Monitoring Requirements. Three commenters 
recommended that water systems be allowed to conduct water quality 
parameter (WQP) monitoring in lieu of continued lead and copper tap 
monitoring. One of these commenters added that this should be allowed 
once the system has demonstrated that it does not have a lead problem. 
This commenter also stated that the new requirements to use lead-free 
solder and plumbing fixtures should preclude problems with lead. Two 
commenters noted the difficulty that water systems are having 
maintaining their current sampling pool because homeowners no longer 
want to participate in the LCR monitoring program. One of these 
commenters recommended using WQP results to ensure corrosion control 
treatment is being adequately maintained and to stop lead and copper 
monitoring after three to five years. The commenter added that once the 
system ceases lead and copper monitoring, it can use public education 
to supplement continuing corrosion control, and can use coupons to 
demonstrate that corrosion rates meet accepted standards.
    EPA Response: While EPA is sensitive to the difficulties associated 
with the monitoring requirements of the LCR, the Agency is also 
concerned about the implications of reduced or discontinued monitoring. 
Significant treatment changes or water chemistry disturbances (such as 
new water sources, major pH/coagulation changes, disinfectant changes, 
or seasonal water/treatment changes) can influence the effectiveness of 
corrosion control, which in turn will require appropriate adjustments 
of treatment. Current regulations require water systems to continue 
monitoring lead and copper levels to assure that water quality changes 
adversely affecting the presence of these contaminants in the drinking 
water are detected and to assure that appropriate adjustments to 
maintain optimal corrosion control are made. Proper process control, 
including water quality and corrosion inhibitor residual concentration 
monitoring in the distribution system, is the key to making any 
corrosion control or other treatment work, and assure the continuation 
of proper water quality. However, EPA recognizes that some changes 
might be justified in the future based on new, scientifically valid, 
information and/or research. EPA is considering aspects such as the 
implications of simultaneous treatment modifications on water quality, 
including lead and copper control, in its research planning. EPA is not 
yet able to determine whether the outcome of such research will provide 
a basis for modifications to the LCR treatment or monitoring

[[Page 42924]]

requirements. As stated in the response in section IV.B.13.a. of 
today's action, EPA has placed the LCR in the data gaps category 
pending the completion of future research.
    c. Corrosion Control Treatment Strategy. Two commenters noted 
concerns regarding the lead and copper corrosion control strategy. One 
commenter indicated that the LCR should be revised to allow systems to 
change corrosion control strategies. The commenter stated that 
considerable development of the corrosion control market has occurred 
since systems made their initial assessments and implemented corrosion 
control programs. The commenter felt that currently, the ``LCR locks 
utilities into a given control strategy,'' when in some instances 
limited pilot work and ongoing WQP monitoring would allow a system to 
re-assesses its treatment and implement an alternative corrosion 
control inhibitor.
    The second commenter indicated that the current corrosion control 
strategies are marginally effective at preventing particulate lead and 
copper from entering the water supply. The commenter recommended that 
EPA consider methods for mitigating the release of insoluble components 
from plumbing fixtures.
    EPA Response: The Agency disagrees that the LCR locks utilities 
into a given control strategy, but feels it is necessary to demonstrate 
a sound basis for re-assessing and implementing an alternative 
treatment strategy in the context of the existing regulation. EPA notes 
that the current regulation provides some flexibility to both States 
and water systems in the choice of a corrosion control strategy. For 
example, in response to its own initiative, a request by a water system 
or other interested party, a State may modify its determination of the 
optimal corrosion control treatment, among those listed in the Federal 
regulation, or may modify optimal WQPs if the State determines such 
changes are necessary to ensure that the system continues to optimize 
corrosion control treatment (40 CFR 141.82(h)).
    The Agency believes that the existing requirements to notify the 
State when changing a corrosion control strategy remain necessary and 
appropriate. After they have optimized corrosion control, water systems 
must notify the State of any treatment changes \7\ within 60 days of 
the change (40 CFR 141.90(a)(3)). The Agency encourages water systems 
to notify the State prior to making any changes thus allowing the 
Primacy Agency to review the changes to reduce the potential for 
detrimental side-effects. In the Agency's experience, changes in 
treatment, such as (but not restricted to) replacement of high pH 
treatment with corrosion inhibitor, changes in coagulant and 
coagulation conditions, changes in disinfection, installation of 
membrane processes, or introduction of chemically different waters into 
the distribution system provide potential for detrimental side-effects. 
Water treatment changes, therefore, should only be done with the 
greatest care and pilot investigations. While changes to treatment can 
be made under the existing regulation, systems should conduct 
additional monitoring (e.g., of lead, copper, and WQPs) until the new 
treatment is fully implemented and stabilized.
---------------------------------------------------------------------------

    \7\ Treatment changes are categorized as changes to any water 
quality treatment process, including (but not restricted to) 
disenfection, disinfection by-product removal, and corrosion 
control.
---------------------------------------------------------------------------

    EPA also recognizes that the current LCR may limit flexibility to 
some extent, particularly in the adoption of new or emerging 
technologies. The original rule attempted to balance this concern with 
the need to provide strong public health protection by ensuring that 
only control strategies of proven effectiveness are adopted. The Agency 
does not have an adequate basis to revise the treatment requirements at 
this time but will continue to monitor new developments, including 
emerging technology. The Agency may consider revisions to the LCR prior 
to the end of the next Six-Year Review cycle if the Agency receives 
new, scientifically-valid, information that provides a basis for 
achieving significant improvement in public health protection or 
significant cost-savings to utilities and their customers while 
maintaining current public health protection.
    EPA has always recognized that the release of insoluble particulate 
material containing lead and copper can be an issue in some water 
systems. While more research may be of interest to improve optimization 
of corrosion control approaches with respect to this source, EPA 
expects that evaluations and pilot studies by water systems should 
include testing and consideration of the relative effectiveness of 
different treatments towards particulate release in systems for which 
it is important.
    d. Lead Levels in School Drinking Water. One commenter was 
concerned that the data on lead levels that was analyzed under the Six-
Year Review of NPDWR standards may not indicate actual lead 
contamination of drinking water sources. As an example, the commenter 
noted that even though Baltimore City is in compliance for lead levels, 
\1/3\ of Baltimore schools are using alternative sources of drinking 
water due to lead contamination. The commenter expressed concern that 
since data obtained from schools, such as the data from Baltimore, was 
not considered in the evaluation of lead contamination in drinking 
water, the most vulnerable population may not be protected from 
exposure to lead. The commenter stated that it is time for the Agency 
to reassess how lead levels are evaluated.
    EPA Response: The LCR is designed to address system-wide problems 
with lead and copper contamination. The rule does not specifically 
target particular structures, such as schools, but rather contains a 
monitoring protocol designed to ensure that the overall levels of lead 
and copper system-wide are minimized. Once optimal treatment is 
implemented, any remaining problems with elevated lead levels in 
schools may be due to plumbing, coolers, or other materials in the 
building. These potential sources of lead in schools are of concern and 
for this reason are explicitly addressed under the provisions of the 
Lead Contamination Control Act of 1988 (LCCA) (sections 1461 to 1465 of 
SDWA). The LCCA directed EPA to publish a guidance manual and testing 
protocol to assist States and schools in identifying sources and 
determining the extent of lead contamination in school drinking water 
and, if necessary, in remedying such contamination. In January 1989, 
the Agency published and distributed the guidance manual, ``Lead in 
School's Drinking Water,'' to States and schools (USEPA, 1989). In 
1994, the Agency updated and revised the guidance manual entitled 
``Lead in Drinking Water in Schools and Non-residential Buildings'' 
(USEPA, 1994). A copy of this manual may be obtained from the Safewater 
website http://www.epa.gov/safewater/consumer/leadinschools.html. In 
addition, the LCCA imposed a ban on the manufacture and sale of water 
coolers that are not lead free. The LCCA requirements are independent 
of the NPDWRs and therefore are not addressed under the Six-Year Review 
process. However, the Agency is continuing to work with schools and 
States to address problems dealing with lead in school drinking water.
14. Lindane ([gamma]-hexachlorocyclohexane)
    In the April 17, 2002, Federal Register, the Agency preliminarily 
placed lindane in the no revision category because a health risk 
assessment was pending at the time of publication. One commenter stated 
that

[[Page 42925]]

the RED risk assessment for lindane, issued after publication of the 
April 17, 2002, Federal Register, should be considered in the Agency's 
review of the NPDWR and expressed concerns regarding the existing 
regulation. The commenter stated that the current NPDWR is based on an 
RfD developed in 1988 on the basis of adverse kidney effects and should 
be revised (USEPA, 1988). The kidney effects were determined to occur 
through a pathway that is not relevant to human health risk assessment. 
The commenter stated that the new OPP toxicological assessment has 
resulted in a significant change to the quantitative dose-response 
assessment for lindane and that there are no data gaps or uncertainties 
which would prevent a revision of the NPDWR for lindane at this time.
    EPA Response: Since the publication of the April 17, 2002, Federal 
Register and receipt of the comment regarding lindane, the Agency has 
finalized the risk assessment for lindane and signed the RED on July 
31, 2002. The remaining paragraphs in this section include a brief 
background discussion about the original promulgation of the lindane 
NPDWR, the results of the appropriate six-year technical reviews and 
the Agency's revise/not revise decision.
    a. Background. EPA published the current NPDWR for lindane on 
January 30, 1991 (56 FR 3526 (USEPA, 1991a)). The NPDWR established an 
MCLG and an MCL of 0.0002 mg/L. The Agency based the MCLG on an RfD of 
0.0003 mg/kg/day and a cancer classification of C, possible human 
carcinogen.
    b. Technical Reviews. EPA updated the risk assessment on July 31, 
2002 (USEPA, 2002h). The new risk assessment established an RfD of 
0.0047 mg/kg/day. The Food Quality Protection Act (FQPA) of 1996 
provides for an additional safety factor of up to 10-fold, if 
necessary, in assessing the risks to infants and children to take into 
account the potential for pre- and post-natal toxicity, and the 
completeness of the toxicity and exposure databases. This is referred 
to as the FQPA safety factor. The Agency concluded that an FQPA safety 
factor of three was required for lindane since there is evidence for 
increased susceptibility of the young demonstrated in a developmental 
neurotoxicity and two-generation reproductive toxicity study in rats. 
The rationale for using an FQPA safety factor of three is detailed in 
the RED.
    In accordance with the 1999 EPA Draft ``Guidelines for Carcinogen 
Risk Assessment'' (USEPA, 1999a), the Agency classified lindane as 
``suggestive evidence of carcinogenicity, but not sufficient to assess 
human carcinogenic potential.'' Based on the RfD for lindane of 0.0047 
mg/kg/day, the application of the additional FQPA safety factor of 
three to this RfD, a 20 percent RSC, and a 10-fold risk management 
factor of suggested evidence of carcinogenicity, EPA used 0.001 mg/L as 
a level for evaluating the occurrence data.
    Analytical or treatment feasibility do not pose any limitations for 
the current MCL and would not be a limiting factor at the 0.001 mg/L 
level (USEPA, 2003a; USEPA 2003g). The Agency's review of possible 
``other regulatory revisions'' did not identify any issues that are 
specific to lindane (USEPA, 2003b).
    EPA evaluated the results of the occurrence and exposure analyses 
for lindane to determine whether possible changes to the standard would 
be likely to result in a meaningful opportunity for cost-savings to 
public water systems and their customers (USEPA, 2003d). Table IV-2 
shows the results of the detailed occurrence and exposure analysis 
based on the 16-State cross-section for concentrations of 0.0002 mg/L 
(the current MCL), and for 0.001 mg/L. Based on the detailed analysis, 
it appears that lindane is unlikely to occur at concentrations above 
0.0002 mg/L in the States used for the cross-section.
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    The results of the detailed occurrence and exposure analysis 
indicate that few, if any, of the 16,098 systems sampled in the 16-
State cross-section might be affected if EPA were to consider levels as 
high as 0.001 mg/L. The current BATs and small system compliance 
technology for lindane have other beneficial effects (e.g., reduction 
of other co-occurring contaminants, or other common impurities) in 
addition to lindane removal. Therefore, if EPA were to consider a 
higher level, the Agency does not know how many of these public water 
systems that are currently treating to comply with the current MCL of 
0.0002 mg/L would be likely to discontinue any treatment that is 
already in place (USEPA, 2002c; USEPA, 2003g).
    c. Current Decision. Although there are new health effects data 
that might support calculation of a less stringent standard for 
lindane, EPA does not believe a revision to the NPDWR for lindane is 
appropriate at this time. In making this decision, the Agency 
considered whether any potential revision to the lindane NPDWR is 
likely to provide a meaningful opportunity for cost-savings to public 
water systems and their customers. After consideration of this factor, 
EPA has decided that any revision to lindane would be a low priority 
activity for the Agency, and, thus, is not appropriate to revise at 
this time because of:
    [sbull] Competing workload priorities;
    [sbull] The administrative costs associated with rulemaking; and
    [sbull] The burden on States and the regulated community to 
implement any regulatory change that resulted.
15. Simazine
    One commenter agreed that simazine should be addressed after the 
risk assessment is completed in 2003 or 2004. The commenter requested 
that the Office of Water (OW) work closely with the OPP on the risk 
assessment at that time. The commenter also recommended that OW address 
the revision of the existing simazine NPDWR before the next review 
cycle year, scheduled for 2008. The commenter believes the extensive 
mammalian toxicology database, submitted as part of the Triazine 
Special Review, can be used in this process.
    EPA Response: OW has been coordinating with OPP for the revision of 
the atrazine and simazine risk assessments. Once the simazine risk 
assessment is completed, EPA will determine whether a compelling reason 
exists to consider review of the simazine NPDWR on an accelerated 
schedule.

C. What Comments Did EPA Receive Regarding the Review of 
Implementation-Related Issues for Chemical NPDWRs?

    Several commenters recommended that EPA ensure consistent 
application of rules by making rules more consistent with respect to 
monitoring frequency, triggers for increased monitoring, criteria for 
returning to routine monitoring, and criteria for reducing sample 
requirements. In addition, commenters suggested that the Agency review 
possible ways for reducing the reporting burden on States, which could 
free up State resources currently used to implement rules.
    One commenter was concerned about monitoring and reporting issues 
in conjunction with CMR. The commenter felt that EPA should not miss an 
opportunity to relieve some of the unnecessary confusion that the 
monitoring requirements of Phase II and V have created. This confusion 
includes issues such as, what a detection is and what the monitoring 
requirements are for systems in States without a waiver program. EPA 
was encouraged to provide this consistency as much as possible, 
including using the standard monitoring framework to allow States and 
water systems to more easily understand rule requirements and reduce 
the need for States to update their data management systems.
    One commenter said EPA should ensure consistent application of 
rules by determining whether or not chronic contaminants should be 
regulated at non-transient non-community water systems (NTNCWSs), and 
review existing NPDWRs to ensure that rules are applied consistently. 
Another commenter recommended that the compliance language for the 
synthetic organic chemicals (SOCs) and volatile organic chemicals 
(VOCs) in the Final Arsenic Rule (66 FR 6975, January 22, 2001 (USEPA, 
2001)) be adopted for the inorganic chemicals (IOCs), and that systems 
not be considered in violation of the MCL until it has completed one 
year of quarterly samples.
    EPA Response: The Agency agrees that consistency across regulations 
is desirable to the extent that it does not jeopardize public health 
protection or the environment.
    As part of the Advanced Notice of Proposed Rulemaking for CMR (62 
FR 36100, July 3, 1997 (USEPA, 1997a)), EPA considered some of the 
issues raised by the commenters. However, during the comment period for 
the CMR, stakeholders generally indicated that the existing monitoring 
framework was sufficient. Most State commenters indicated that it would 
be too burdensome to adopt CMR. As a result, the Agency decided to take 
no further action on the CMR. However, the Agency established a 
standardized monitoring framework which applies to all of the regulated 
chemical and radiological contaminants (except lead and copper). The 
new chemical and radiological rules that EPA has promulgated (e.g., 
arsenic and radionuclides) are coordinated with the standardized 
monitoring framework. The Agency made special efforts to ensure that 
the reduced monitoring periods are in line with the 3-year compliance 
periods in the standardized monitoring framework.
    To assist States with understanding rule requirements, the Agency 
conducted a series of Phase II/V training in 2001. The training 
provided information to help States make informed decisions about 
reducing quarterly monitoring requirements. With respect to reduced 
monitoring, States currently have the flexibility to reduce the 
frequency of monitoring and/or to waive sampling requirements for any 
given contaminant after minimum criteria are met to demonstrate that 
the system is reliably and consistently below the MCL and/or not 
vulnerable to contamination.
    NTNCWSs are traditionally regulated for chronic contaminants. 
However, through an alternative mechanism, the Agency is currently 
evaluating risk and exposure as they pertain to NTNCWS monitoring 
requirements. This review will not be completed in time for this Six-
Year Review process. Until all the issues have been identified and 
specific options have been formulated, it will not be clear if a 
revision to regulations is indicated.
    EPA intends to consistently implement compliance determination 
provisions for IOCs, SOCs, and VOCs for all NTNCWSs and community water 
systems, as described in the preamble to the Final Arsenic Rule (66 FR 
6975 at 6990, January 22, 2001 (USEPA, 2001)). The rule makes 
compliance determinations based on a running annual average. The 
clarifications to compliance determinations for SOCs, IOCs, and VOCs 
are based on the average of the initial MCL exceedance and any 
subsequent State-required confirmation samples. States have the 
flexibility to require confirmation samples and more frequent 
monitoring, in addition to required quarterly samples. The average of 
the exceedance and confirmation sample constitutes the first quarterly 
sample. Compliance with the MCL is based on the average of the first 
quarterly sample and three

[[Page 42928]]

additional samples over a period of one year, unless any one quarterly 
sample would cause the running annual average to exceed the MCL. Then 
the system is out of compliance immediately.

D. What Comments Did EPA Receive on the Total Coliform Rule?

    Several commenters addressed the TCR. Several commenters raised 
several issues relating to monitoring. Some contended that routine 
monitoring should be focused on critical locations in the distribution 
system, rather than on the current requirement to monitor all parts of 
the distribution system. They also urged EPA to allow the use of 
dedicated sampling taps. Some commenters argued for allowing a finished 
water storage reservoir as a routine monitoring site. Two commenters 
urged EPA to focus on E. coli as the measure of water quality in the 
distribution system, rather than on total coliforms. In addition to 
routine monitoring, a few commenters addressed the topic of repeat 
samples after a total coliform-positive sample. One commenter, for 
example, urged EPA to eliminate the requirement to take upstream and 
downstream repeat samples after a total coliform-positive sample. 
Environmental groups urged EPA to strengthen the TCR and other rules 
that protect against pathogens, and exhorted EPA not to ease the TCR 
burden such that public health is compromised.
    EPA Response: EPA's announcement in the April 17, 2002, Federal 
Register was only intended to discuss the Agency's intent to begin the 
process for revising the TCR. EPA will consider the commenters' 
suggestions as part of the revision process. As stated in the April 17, 
2002, Federal Register, the Agency plans to consider revisions to the 
TCR with new requirements for ensuring the integrity of distribution 
systems. The Agency remains committed to obtaining input from 
stakeholders as part of the rule development process. EPA agrees with 
the comment that public health should not be compromised, and will 
consider only those revisions that will assure public health 
protection.

E. What Comments Did EPA Receive on Research Needs?

    Commenters found that EPA's information on potential research 
resulting from the review of NPDWRs would be better represented by a 
summary of research needs that were identified by the Agency. 
Commenters felt that this summary is important to inform future 
regulatory decisions. Commenters also suggested additional research 
needs that had not been identified by EPA in its preliminary review.
    EPA Response: EPA agrees that the identification of research needs 
is an important component of the review of NPDWRs. Research findings 
may support future reviews and/or revisions to NPDWRs.
    The Agency is considering research needs that it identified as part 
of the review as well as those suggested by commenters. EPA will 
continue to identify areas where data are lacking. Dialogue with 
industry and other groups, including those that sponsor or conduct 
research on priority areas, would be beneficial to the drinking water 
program. Collaboration in sponsoring studies can provide multiple 
benefits.
    There are two research needs associated with the Six-Year Review 
that are being addressed through mechanisms external to EPA. The 
National Research Council of the National Academy of Sciences is 
conducting an assessment of recent data on fluoride health effects. In 
addition, the National Toxicology Program is conducting a study on 
chromium VI toxicity. Both of these research efforts are discussed in 
the April 17, 2002, Federal Register announcement of EPA's preliminary 
revise/not revise decisions. The current review identified several 
general and specific areas of potential research related to treatment. 
The treatment-related research areas are briefly discussed in the 
Treatment Feasibility Document (USEPA, 2003g).
    EPA is currently in the process of examining whether specific 
research needs exist within each of the Six-Year Review areas of 
regulatory consideration (i.e., health effects, analytical methods, 
treatment, implementation, and occurrence/exposure). Some of the 
research needs identified during the Six-Year Review effort will be 
discussed in the context of the Multi-Year Plan (MYP) for drinking 
water. The MYP describes the EPA Office of Research and Development's 
fiscal year 2003 to 2010 research program to support the regulatory 
development activities of the EPA Office of Water. EPA plans to make 
this document available to the public in 2003.

V. References

National Drinking Water Advisory Council (NDWAC). 2000. Recommended 
Guidance for Review of Existing National Primary Drinking Water 
Regulations. November 2000. Available on the Internet at: http://www.epa.gov/safewater/ndwac/guidfnl.pdf.
National Research Council (NRC). 1993. Health Effects of Ingested 
Fluoride. National Academy Press, Washington, DC. August 1993. 
Available on the Internet at: http://books.nap.edu/books/030904975X/html/R1.html.
National Toxicology Program (NTP). 2002. NTP study of the hexavalent 
chromium compound sodium dichromate dihydrate. Available on the 
Internet at: http://ntp-server.niehs.nih.gov/htdocs/Studies/HexChromium/hexchromiumpg.html.
Schroeder, H.A., Mitchener, M. and Nason, A.P. 1970. Zirconium, 
niobium, antimony, vanadium and lead in rats: life term studies. 
Journal of Nutrition. 100: 59-68.
Senate Report. 1995. Committee of Environment and Public Works, Safe 
Drinking Water Act Amendments of 1995, S. Doc. No. 169, 104th Cong., 
1st Sess. 38 (1995).
USEPA. 1986. EPA Guidelines for Carcinogen Risk Assessment. Federal 
Register. Vol. 51, No. 185. p. 33992, September 24, 1986.
USEPA. 1987. National Primary Drinking Water Regulations--Synthetic 
Organic Chemicals; Monitoring for Unregulated Contaminants; Final 
Rule. Federal Register. Vol. 52, No. 130. p. 25690, July 8, 1987.
USEPA. 1988. Integrated Risk Information System, gamma-
Hexachlorocyclohexane. Available on the Internet at: http://www.epa.gov/iris/subst/0065.htm.
USEPA. 1989. Lead in School Drinking Water. EPA 570/9-89-001. 
January 1989.
USEPA. 1991a. National Primary Drinking Water Regulations--Synthetic 
Organic Chemicals and Inorganic Chemicals; Monitoring for 
Unregulated Contaminants; National Primary Drinking Water 
Regulations Implementation; National Secondary Drinking Water 
Regulations; Final Rule. Federal Register. Vol. 56, No. 30. p. 3526, 
January 30, 1991.
USEPA. 1991b. Maximum Contaminant Level Goals and National Primary 
Drinking Water Regulations for Lead and Copper; Final Rule. Federal 
Register. Vol. 56, No. 110. p. 26460, June 7, 1991.
USEPA. 1992. Final Regulatory Impact Analysis National Primary 
Drinking Water Regulations: Phase V Synthetic Organic and Inorganic 
Chemicals. February 1992.
USEPA. 1993. Reregistration Eligibility Decision (RED)--Glyphosate. 
EPA Report 738-R-93-014. Washington, DC: Office of Prevention, 
Pesticides, and Toxic Substances. September 1993. Available on the 
Internet at: http://www.epa.gov/oppsrrdl/REDs/old_reds/glyphosate.pdf.
USEPA. 1994. Lead in Drinking Water in Schools and Non-Residential 
Buildings. EPA 812-B-94-002. Office of Water. April 1994.
USEPA. 1997a. National Primary Drinking Water Regulations--Advance 
Notice of Proposed Rulemaking. Federal Register. Vol. 62, No. 156. 
p. 36100, July 3, 1997.
USEPA. 1997b. Alternative Monitoring Guidelines. EPA 816-R-97-011. 
August 1997. Available on the Internet at: http:/

[[Page 42929]]

/www.epa.gov/safewater/regs/pmrfin.html.
USEPA. 1998. IRIS, Beryllium and Compounds. Available on the 
Internet at: http://www.epa.gov/iris/subst/0012.htm.
USEPA. 1999a. Guidelines for Carcinogen Risk Assessment. NCEA-F-0644 
Review Draft. Environmental Protection Agency Risk Assessment Forum. 
Washington, DC. July 1999.
USEPA. 1999b. Revisions to the Unregulated Contaminant Monitoring 
Regulations for Public Water Systems; Final Rule. Federal Register. 
Vol. 64, No. 180. p. 50556, September 17, 1999.
USEPA. 1999c. A Review of Contaminant Occurrence in Public Water 
Systems. EPA 816-R-99-006. 78 pp. November 1999.
USEPA. 2000. National Primary Drinking Water Regulations for Lead 
and Copper; Final Rule. Federal Register. Vol. 65, No. 8. p. 1950, 
January 12, 2000.
USEPA. 2001. National Primary Drinking Water Regulation: Arsenic and 
Clarifications to Compliance and New Source Contaminants Monitoring; 
Final Rule. Federal Register. Vol. 66. No. 14. p. 6975, January 22, 
2001.
USEPA. 2002a. Integrated Risk Information System (IRIS); 
Announcement of 2002 Program; Request for Information; Notice. 
Federal Register. Vol. 67, No. 6. p. 1212, January 9, 2002.
USEPA. 2002b. Water Treatment Technology Feasibility Support 
Document for Chemical Contaminants; In support of EPA Six-Year 
Review of National Primary Drinking Water Regulations. EPA 815-D-02-
001. Draft. February 2002.
USEPA. 2002c. An Evaluation of Available Economic Information in 
Support of the Six-Year Review of Existing National Primary Drinking 
Water Regulations. Memo from Marc Parrotta, Targeting and Analysis 
Branch, Office of Ground Water and Drinking Water. March 2002.
USEPA. 2002d. EPA Protocol for Review of Existing National Primary 
Drinking Water Regulations. EPA 815-D-02-004. Draft. March 2002.
USEPA. 2002e. Occurrence Estimation Methodology and Occurrence 
Findings Report for the Six-Year Review of Existing National Primary 
Drinking Water Regulations. EPA 815-D-02-005. Draft. March 2002.
USEPA. 2002f. Occurrence Summary and Use Support Document for the 
Six-Year Review of Existing National Primary Drinking Water 
Regulations. EPA 815-D-02-006. Draft. March 2002.
USEPA. 2002g. National Primary Drinking Water Regulations--
Announcement of the Results of EPA's Review of Existing Drinking 
Water Standards and Request for Public Comment; Proposed Rule. 
Federal Register. Vol. 67, No. 74. p. 19030, April 17, 2002.
USEPA. 2002h. Reregistration Eligibility Decision (RED)--Lindane. 
EPA 738-R-02-012. Office of Prevention, Pesticides, and Toxic 
Substances. July 2002. Available on the Internet at: http://www.epa.gov/oppsrrdl/REDs/lindane_red.pdf.
USEPA. 2002i. Integrated Risk Information System (IRIS), 1,1-
Dichloroethylene. August 2002. Available on the Internet at: http://www.epa.gov/iris/subst/0039.htm.
USEPA. 2003a. Analytical Feasibility Support Document for the Six-
Year Review of Existing National Primary Drinking Water Regulations 
(Reassessment of Feasibility for Chemical Contaminants). EPA 815-R-
03-003. Final. March 2003.
USEPA. 2003b. Consideration of Other Regulatory Revisions for 
Chemical Contaminants in Support of the Six-Year Review of National 
Primary Drinking Water Regulations. EPA 815-R-03-005. Final. June 
2003.
USEPA. 2003c. EPA Protocol for Review of Existing National Primary 
Drinking Water Regulations. EPA 815-R-03-002. Final. June 2003.
USEPA. 2003d. Occurrence Estimation Methodology and Occurrence 
Findings Report for the Six-Year Review of Existing National Primary 
Drinking Water Regulations. EPA 815-R-03-006. Final. June 2003.
USEPA. 2003e. Public Comment and Response Summary for the Six-Year 
Review of National Primary Drinking Water Regulations. EPA 815-R-03-
001. Final. June 2003.
USEPA. 2003f. Six-Year Review--Chemical Contaminants--Health Effects 
Technical Support Document. EPA 822-R-03-008. Final. June 2003.
USEPA. 2003g. Water Treatment Technology Feasibility Support 
Document for Chemical Contaminants; In Support of EPA Six-Year 
Review of National Primary Drinking Water Regulations. EPA 815-R-03-
004. Final. June 2003.
USEPA. 2003h. Integrated Risk Information System (IRIS); 
Announcement of 2003 Program; Request for Information and 
Announcement of Workshop; Notice. Federal Register. Vol. 68, No. 24. 
p. 5870, February 5, 2003.


    Dated: July 11, 2003.
Linda J. Fisher,
Acting Administrator.
[FR Doc. 03-18152 Filed 7-17-03; 8:45 am]
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