[Federal Register Volume 68, Number 250 (Wednesday, December 31, 2003)]
[Notices]
[Pages 75507-75515]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-32211]


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ENVIRONMENTAL PROTECTION AGENCY

[OW-FRL-7605-2]


National Recommended Water Quality Criteria for the Protection of 
Human Health

AGENCY: Environmental Protection Agency.

ACTION: Notice of availability.

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SUMMARY: Pursuant to section 304(a) of the Clean Water Act (CWA), the 
Environmental Protection Agency (EPA) is announcing the availability of 
updated national recommended water quality criteria for the protection 
of human health for the following fifteen pollutants: chlorobenzene; 
cyanide; 1,2-dichlorobenzene; 1,4-dichlorobenzene; 1,1-
dichloroethylene; 1,3-

[[Page 75508]]

dichloropropene; endrin; ethylbenzene; hexachlorocyclopentadiene; 
lindane; thallium; toluene; 1,2-transdichloroethylene; 1,2,4-
trichlorobenzene; and vinyl chloride.
    The criteria are based on EPA's 2000 methodology for deriving human 
health water quality criteria and supercede criteria for these 
chemicals that the Agency published before this notice.
    EPA's recommended section 304(a) water quality criteria are 
guidance to States and authorized Tribes in adopting water quality 
standards for protecting human health. They are also a scientific basis 
for developing controls of discharges or releases of pollutants. They 
are guidance to EPA for promulgating Federal regulations under CWA 
section 303(c), when such action is necessary.
    Under the CWA and its implementing regulations, States and 
authorized Tribes are to adopt water quality criteria to protect 
designated uses (e.g., public water supply, recreational use, 
industrial use). EPA's recommended human health water quality criteria 
do not substitute for the CWA or regulations, nor are they regulations 
themselves. Thus, EPA's recommended criteria do not impose legally 
binding requirements. States and authorized Tribes have the discretion 
to adopt, where appropriate, other scientifically defensible water 
quality standards that differ from these recommendations.

ADDRESSES: Copies of documents specifically referenced in this notice 
and scientific views received are in Docket ID No. OW-2002-0054. 
Materials in the public docket are 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 Office 
of Water Docket is (202) 566-2426. A reasonable fee will be charged for 
copies. An electronic version of the public docket is available through 
EPA's electronic public docket and comment system, EPA Dockets, at 
http://www.epa.gov/edocket/. Once in the system, select ``search,'' 
then key in the appropriate docket identification number.

FOR FURTHER INFORMATION CONTACT: Cindy Roberts, Health and Ecological 
Criteria Division (4304T), U.S. EPA, Ariel Rios Building, 1200 
Pennsylvania Ave., NW., Washington, DC 20460; (202) 566-1124; 
[email protected].

SUPPLEMENTARY INFORMATION:

General Information

A. Interested Entities

    Entities potentially interested in today's notice are those that 
produce, use, or regulate chlorobenzene; cyanide; 1,2-dichlorobenzene; 
1,4-dichlorobenzene; 1,1-dichloroethylene; 1,3-dichloropropene; endrin; 
ethylbenzene; hexachlorocyclopentadiene; lindane; thallium; toluene; 
1,2-transdichloroethylene; 1,2,4-trichlorobenzene; and vinyl chloride. 
Categories and entities interested in today's notice include:

------------------------------------------------------------------------
                Category                 Examples of interested entities
------------------------------------------------------------------------
States, Authorized Tribes, and           NPDES Authorized States, Tribes
 Jurisdictional Governments.              and Jurisdictions.
Industry...............................  Industries discharging
                                          pollutants to surface waters
                                          or to publically-owned
                                          treatment works discharging
                                          pollutants to surface waters.
Municipalities.........................  Publically-owned treatment
                                          works discharging pollutants
                                          to surface waters.
------------------------------------------------------------------------

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be interested in this 
notice. This table lists the types of entities that EPA is now aware 
could potentially be interested in this notice. Other types of entities 
not listed in the table could also be interested.

B. How Can I Get Copies of the National Recommended Water Quality 
Criteria for the Protection of Human Health and Other Related 
Information?

    1. Docket. EPA has established an official public docket for this 
notice under Docket ID No. OW-2002-0054. The official public docket 
consists of the documents specifically referenced in this notice, any 
public scientific views received, and other information related to this 
announcement. 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 Office of Water Docket is (202) 566-2426. A reasonable 
fee will be charged for copies.
    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 scientific views 
submitted by the public, access the index listing of the contents of 
the official public docket, and to 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 B.1. Once in the system, select ``search,'' then 
key in the appropriate docket identification number.

Table of Contents

I. Background Information
    A. What are human health water quality criteria?
    B. How is the 2000 Human Health Methodology used?
    C. How does EPA use its recommended water quality criteria?
    D. What is the relationship between 304 (a) criteria and your 
State or Tribal water quality standards?
    E. May States and authorized Tribes adopt water quality criteria 
based on local conditions?
    F. How does the review and approval of State and Tribal water 
quality standards affect water quality criteria adopted by States 
and authorized Tribes?
II. Human Health Water Quality Criteria Revisions
    A. What are the criteria revisions?
    B. What are EPA's responses to the scientific views received on 
the criteria revisions?
    C. Were other views submitted?

I. Background Information

A. What Are Human Health Water Quality Criteria?

    Human health water quality criteria are numeric values that 
describe ambient water concentrations that protect human health from 
the harmful effects of pollutants in ambient water. These criteria are 
developed under CWA section 304(a) and are based solely on data and 
scientific judgments about the relationship between pollutant

[[Page 75509]]

concentrations and environmental and human health effects. Human health 
water quality criteria do not reflect consideration of economic impacts 
or the technological feasibility of meeting the chemical concentrations 
in ambient water.
    CWA section 304(a)(1) requires EPA to develop and publish and, from 
time to time, revise criteria for water quality that accurately reflect 
the latest scientific knowledge. EPA's recommended section 304(a) water 
quality criteria provide guidance to States and authorized Tribes in 
adopting water quality standards for protection of human health and can 
be used as a scientific basis for developing controls of discharges or 
releases of pollutants. The criteria also provide guidance to EPA when 
promulgating Federal regulations under CWA section 303(c), when such 
action is necessary.

B. How Is the 2000 Human Health Methodology Used?

    In November 2000, EPA published the revised Methodology for 
Deriving Ambient Water Quality Criteria for the Protection of Human 
Health (2000) (EPA-822-B-00-004, October 2000; hereafter referred to as 
the ``2000 Human Health Methodology''). Before this, the Agency 
developed recommended human health water quality criteria using the 
1980 Guidelines and Methodology Used in the Preparation of Health 
Effects Assessment Chapter of the Consent Decree Water Criteria 
Documents (45 FR 79347, called the ``1980 Methodology''). The 2000 
Human Health Methodology incorporates significant scientific advances 
that have occurred over the last two decades, particularly in the areas 
of cancer and noncancer risk assessments (using new information, 
procedures, and published Agency guidelines), exposure assessments 
(using new studies on human intake and exposure patterns, and new 
Agency guidelines), and methodologies to estimate bioaccumulation in 
fish. EPA will use the 2000 Human Health Methodology to develop new 
section 304(a) water quality criteria for additional pollutants and to 
revise existing section 304(a) water quality criteria. The 2000 Human 
Health Methodology is an important part of EPA's efforts to improve the 
quality of the Nation's waters and strengthen the overall scientific 
basis of water quality criteria. Furthermore, the 2000 Human Health 
Methodology will help States and authorized Tribes address their unique 
water quality issues and make risk management decisions to protect 
human health consistent with CWA section 303(c). The 2000 Human Health 
Methodology provides a detailed means for developing water quality 
criteria, including systematic procedures for evaluating cancer risk, 
noncancer health effects, human exposure, and bioaccumulation potential 
in fish.

C. How Does EPA Use Its Recommended Water Quality Criteria?

    Water quality standards generally consist of designated uses (e.g., 
public water supply, recreational use, industrial use), water quality 
criteria to protect those uses, a policy for antidegradation (that 
maintains and protects existing uses and water quality conditions), and 
general policies for application and implementation of water quality 
standards. As part of the water quality standards triennial review 
process defined in CWA section 303(c)(1), States and authorized Tribes 
are responsible for maintaining and revising water quality standards. 
Section 303(c)(1) requires States and authorized Tribes to review and, 
if appropriate, modify their water quality standards at least once 
every three years. EPA's recommended section 304(a) water quality 
criteria may form the basis for Agency decisions, both regulatory and 
non-regulatory, until they are superseded by EPA's publication of new 
or revised section 304(a) water quality criteria. These recommended 
water quality criteria are used in the following ways:
    (1) as guidance to States and authorized Tribes in adopting water 
quality standards,
    (2) as guidance to EPA in promulgating Federal water quality 
standards,
    (3) to interpret a State's narrative water quality standard (in the 
absence of a State adopted numeric standard) in order to establish 
National Pollutant Discharge Elimination System (NPDES) water quality-
based permit limits, and
    (4) for all other purposes of CWA section 304(a).
    Two distinct purposes are served by the section 304(a) water 
quality criteria. The first is as guidance to the States and authorized 
Tribes in the development and adoption of water quality criteria that 
will protect designated uses for their waters. The second is as 
guidance for promulgation of Federal water quality criteria for States 
and authorized Tribes, when such action is necessary under the terms of 
the CWA.

D. What Is the Relationship Between 304(a) Criteria and Your State or 
Tribal Water Quality Standards?

    States and authorized Tribes must adopt water quality criteria that 
protect designated uses pursuant to CWA section 303(c)(2)(A). 
Protective criteria are based on a sound scientific rationale and must 
contain sufficient parameters or components to protect the designated 
uses. Water quality criteria may be expressed in either narrative or 
numeric form. States and authorized Tribes may use one of four 
approaches when adopting water quality criteria:
    (1) Establish numerical values based on section 304(a) recommended 
water quality criteria,
    (2) Modify the section 304(a) recommended water quality criteria to 
reflect site-specific conditions,
    (3) Use other scientifically defensible methods to derive 
protective water quality criteria, and
    (4) Establish narrative water quality criteria where numeric 
criteria cannot be determined or to supplement numeric water quality 
criteria.
    EPA encourages States and authorized Tribes to use EPA's section 
304(a) water quality criteria as guidance when adopting water quality 
standards consistent with CWA section 303(c) and the Federal 
regulations at 40 CFR part 131.

E. May States and Authorized Tribes Adopt Water Quality Criteria Based 
on Local Conditions?

    EPA encourages States and authorized Tribes to develop and adopt 
water quality criteria to reflect local and regional conditions. In the 
2000 Human Health Methodology, EPA published default values for risk 
level, fish intake, drinking water intake, and body weight for use by 
EPA, States or authorized Tribes in deriving human health water quality 
criteria. EPA believes these default values result in water quality 
criteria that protect the general population. States and authorized 
Tribes may also use these default values for their own water quality 
criteria, or they may use other values more representative of local 
conditions if they have data supporting the alternative values.

F. How Does the Review and Approval of State and Tribal Water Quality 
Standards Affect Water Quality Criteria Adopted by States and 
Authorized Tribes?

    In 2000, EPA published new regulations addressing its review and 
approval of water quality standards adopted by States and authorized 
Tribes (see 65 FR 24642; April 27, 2000.) Under the new regulations, 
(codified at 40 CFR 131.21(c)-(f)), State or authorized Tribal water 
quality standards that were adopted by law or regulation before May 30, 
2000, are in

[[Page 75510]]

effect for CWA purposes unless superseded by replacement Federal water 
quality standards (see 40 CFR 131.21(c)). However, under the new 
regulation, State or authorized Tribal water quality criteria adopted 
into State or Tribal law or regulation on or after May 30, 2000, are in 
effect for CWA purposes only after EPA approves any new or revised 
water quality standards. Therefore, new or revised water quality 
criteria adopted by States or authorized Tribes would not take effect 
for CWA purposes until after EPA approves them.

II. Human Health Water Quality Criteria Revisions

A. What Are the Criteria Revisions?

    Today, EPA is announcing the availability of national recommended 
water quality criteria for the protection of human health for the 
following fifteen pollutants: Chlorobenzene; cyanide; 1,2-
dichlorobenzene; 1,4-dichlorobenzene; 1,1-dichloroethylene; 1,3-
dichloropropene; endrin; ethylbenzene; hexachlorocyclopentadiene; 
lindane; thallium; toluene; 1,2-transdichloroethylene; 1,2,4-
trichlorobenzene; and vinyl chloride. The updated criteria are based on 
EPA's new methodology for deriving human health water quality criteria 
(i.e., the 2000 Human Health Methodology), and they supercede criteria 
previously published by the Agency.
    These criteria represent partial updates of the section 304(a) 
water quality criteria, as described in both the draft Methodology 
revisions and the Federal Register notice that accompanied the final 
Methodology (65 FR 66444; November 3, 2000). EPA believes that updating 
a limited number of components for which there are available data or 
improved science (i.e., a partial update) is a reasonable and efficient 
way to more frequently publish revised section 304(a) water quality 
criteria. EPA has also described its process for publishing revised 
criteria [see National Recommended Water Quality Criteria--Correction 
(64 FR 19781; or EPA 822-Z-99-001) or the Federal Register notice for 
the final Methodology (65 FR 66444)].
    Because recalculation of these fifteen criteria resulted in 
significant changes, EPA issued a Federal Register notice soliciting 
scientific views on the criteria on December 27, 2002 (67 FR 79091). 
This Federal Register Notice was issued in accordance with the 
published process for revising section 304(a) water quality criteria. 
EPA considered the scientific views received in response to the 
December 27, 2002, Federal Register notice. All criteria concentrations 
in this Notice are the same as those published in the December 27, 2002 
(67 FR 79091), with the exception of the criterion for protecting human 
health from consumption of organism only for cyanide. (See section B, 
response to Scientific view b, Incidental ingestion should be 
considered when deriving human health water quality criteria for toxic 
pollutants with a low BCF.) Table II-1 presents the updated criteria, 
as well as the components used in their derivation (e.g., 
bioconcentration factor, relative source contribution).

                            Table II-1.--Revised Human Health Water Quality Criteria
----------------------------------------------------------------------------------------------------------------
                                                  Human health water quality
                                                 criteria for consumption of:
                                               --------------------------------
      Priority pollutant            CAS No.         Water +                                Components
                                                 organism (ug/   Organism only
                                                      L)            (ug/L)
----------------------------------------------------------------------------------------------------------------
Thallium......................         7440280            0.24            0.47  RfD = 6.8E-5, BCF = 116 (RfD
                                                                                 listed is for thallium (I)
                                                                                 sulfate 7446-18-6), RSC = 20%,
                                                                                 FI = 17.5.
Cyanide.......................           57125             140            *140  RfD = 2E-2, BCF = 1, RSC = 20%,
                                                                                 FI = 17.5.
Chlorobenzene.................          108907             130           1,600  RfD = 2E-2, BCF = 10.3, RSC =
                                                                                 20%, FI = 17.5.
1,1-Dichloroethylene..........           75354             330           7,100  RfD = 5E-2, RSC = 20%, BCF =
                                                                                 5.6, FI = 17.5.
1,3-Dichloropropene...........          542756            0.34              21  *q1 = 0.1, BCF = 1.9, FI = 17.5.
Ethylbenzene..................          100414             530           2,100  RfD = 1E-1, BCF = 37.5, RSC =
                                                                                 20%, FI = 17.5.
Toluene.......................          108883           1,300          15,000  RfD = 2E-1, BCF = 10.7, RSC =
                                                                                 20%, FI = 17.5.
1,2-Trans-Dichloro-ethylene...          156605             140          10,000  RfD = 2E-2, BCF = 1.58, RSC =
                                                                                 20%, FI = 17.5.
Vinyl Chloride................           75014           0.025             2.4  *q1 = 1.4 (LMS exposure from
                                                                                 birth), BCF = 1.17, FI = 17.5.
1,2-Dichlorobenzene...........           95501             420           1,300  RfD = 9E-2, BCF = 55.6, RSC =
                                                                                 20%, FI = 17.5.
1,4-Dichlorobenzene...........          106467              63             190  ADI = 1.34E-2, (ADI for 1,2-DCB
                                                                                 used), BCF = 55.6, RSC = 20%,
                                                                                 FI = 17.5.
Hexachlorocyclo-pentadiene....           77474              40           1,100  RfD = 6E-3, BCF = 4.34, RSC =
                                                                                 20%, FI = 17.5.
1,2,4-Trichloro-benzene.......          120821              35              70  RfD = 1E-2, BCF = 114, RSC = 20
                                                                                 %, FI = 17.5.
gamma-BHC (Lindane)...........           58899            0.98             1.8  RfD= 3E-4, BCF = 130, RSC= 20%,
                                                                                 FI = 17.5.
Endrin........................           72208           0.059           0.060  RfD = 3E-4, BCF = 3970, RSC =
                                                                                 20%, FI = 17.5.
----------------------------------------------------------------------------------------------------------------
RfD = reference dose; q1* = cancer potency factor; ADI = allowable daily intake; BCF = bioconcentration factor;
RSC = relative source contribution; FI = fish intake
*This recommended water quality criterion is expressed as total cyanide, even though the IRIS RfD we used to
  derive the criterion is based on free cyanide. The multiple forms of cyanide that are present in ambient water
  have significant differences in toxicity due to their differing abilities to liberate the CN-moiety. Some
  complex cyanides require even more extreme condition than refluxing with sulfuric acid to liberate the CN-
  moiety. Thus, these complex cyanides are expected to have little or no `bioavailability' to humans. If a
  substantial fraction of the cyanide present in a water body is present in a complexed form (e.g., Fe4[Fe(CN
  )6]3), this recommended criterion may be over conservative.

    EPA received much support for revising criteria based on partially 
updated components of the criteria equations as a way of increasing the 
frequency of scientific improvements to the nationally recommended 
criteria. For EPA to consider a water quality criterion revision based 
on a partial update to be acceptable, the components being used in the 
update should be comprehensive (e.g., a revised reference dose or 
cancer dose-response assessment), stand alone, and be based on new 
national or local data. The recalculation of all fifteen water quality 
criteria integrates the updated national default freshwater/estuarine 
fish consumption rate of 17.5 grams/day. Thirteen of the criteria were 
calculated using a previously-determined relative source contribution 
(RSC) value from the national primary drinking water standards for the 
same chemicals. EPA also incorporated into the recalculations

[[Page 75511]]

a new cancer potency factor (q1*) for 1,3-dichloropropene and vinyl 
chloride, and a new reference dose (RfD) for 1,1-dichloroethylene, 
hexachlorocyclopentadiene, and lindane. These values were already 
published in the Agency's Integrated Risk Information System (IRIS). 
Both an RfD and q1* are available in IRIS for 1,3-dichloropropene and 
vinyl chloride. Because it resulted in more protective criteria, EPA 
used the q1* to derive the criteria in these cases rather than the RfD.
    We derived the water quality criteria presented here with 
bioconcentration factors (BCFs) or field-measured bioaccumulation 
factors (BAFs) based on the 1980 Methodology. These values are 
consistent with those used to promulgate human health water quality 
criteria for priority toxic pollutants in rules such as the 1992 
National Toxics Rule and the 2000 California Toxics Rule.

B. What Are EPA's Responses to the Scientific Views Received on the 
Criteria Revisions?

    This section summarizes the scientific views received in response 
to the December 27, 2002, Federal Register Notice. It also presents 
EPA's responses to the scientific views.
1. 2000 Human Health Methodology
    a. Support application of EPA's new methodology for deriving human 
health water quality criteria.
    Scientific View--One submitter expressed support of EPA's 
application of the new human health methodology, including using more 
current estimates of daily fish intake, relative source contribution 
(for noncarcinogenic effects), and updated toxicological data.
    Response--EPA acknowledges and appreciates the submitter's support.
    b. Incidental ingestion should be considered when deriving human 
health water quality criteria for toxic pollutants with a low BCF.
    Scientific View--One submitter indicated that EPA should consider 
acute and chronic effects from incidental ingestion of water when 
deriving human health water quality criteria associated with the 
consumption of ``organisms only'' for toxic pollutants with a low BCF. 
It is possible to exceed the RfD based on chronic toxicity when 
incidental ingestion occurs at the criterion concentration established 
for protecting human health for consumption of organisms only. Before 
finalizing the criteria revisions, EPA should compare the potential for 
acute toxicity from incidental ingestion of acutely toxic substances to 
the threshold for acute toxicity. The submitter uses cyanide as an 
example of a chemical for which acute and chronic effects from 
incidental ingestion of water should be considered as we develop human 
health water quality criteria.
    Response--In developing the 2000 Human Health Methodology, EPA 
reviewed estimates of incidental water ingestion rates averaged over 
time. Based on this review, EPA generally believes that the averaged 
amount is negligible and will not impact the chemical criteria values 
that represent both drinking water and fish ingestion, unless (as 
indicated in the 2000 Methodology) the chemical exhibits minimal or no 
bioaccumulation potential.
    EPA expects that the cyanide criterion for consumption of organisms 
only established based on the 2000 Human Health Methodology is 
generally protective of human health. However, cyanide is an acutely 
toxic substance (with a low bioaccumulation potential), and the 
resulting criterion of 16,000 ug/L derived for consumption of organism 
only may not protect humans from acutely toxic effects. Thus, EPA 
considers it prudent health policy to establish the criterion 
concentration for consumption of organisms only at the same level as 
the value for protecting human health for consumption of water and 
organisms (140 ug/L). The EPA's IRIS RfD that we used to derive the 
criterion is based on free cyanide. If a substantial fraction of the 
cyanide present in a water body is present in a complexed form (e.g., 
Fe4[Fe(CN)6]3), this recommended 
criterion may be overly conservative. State and authorized Tribes, 
however, have the discretion to modify section 304(a) criteria to 
reflect site-specific conditions.
    c. Future updates of human health water quality criteria should 
consider additional exposure routes.
    Scientific view--A submitter supported EPA's plans to include 
additional exposure routes resulting from recreational activities 
(e.g., dermal, inhalation).
    Response--EPA appreciates the submitter's support. As stated in the 
published draft methodology revisions (65 FR 66444; November 3, 2000) 
and in Response to Peer Review Comments on Draft Revisions to the 
Methodology for Deriving Ambient Water Quality Criteria for the 
Protection of Human Health (EPA-822-R-00-009, August 2000), EPA 
acknowledges that the potential for inhalation and dermal exposures 
exist, and an approach to account for them in the context of developing 
individual water quality criteria is appropriate. EPA intends to refine 
the 2000 Human Health Methodology in the future to incorporate guidance 
on inhalation and dermal exposures.
    d. National default BCFs and BAFs should not be used in the 
derivation of water quality criteria.
    Scientific view--A submitter stated that the 15 proposed human 
health water quality criteria are based, in part, on using national 
default BCFs or BAFs without demonstrating that a statistically and 
ecologically significant correlation exists between the compound in the 
water column and levels found in fish tissues. The submitter uses 
methylmercury as an example of a chemical for which that correlation 
has not yet been demonstrated. As a consequence, the submitter strongly 
objects to the use of BCFs or BAFs in deriving the criteria. The 
submitter further stated that EPA should notify States and authorized 
Tribes not to adopt the revised criteria into State or Tribal standards 
until they can confirm a statistically significant (and important) 
relationship between water column concentrations and fish tissue 
concentrations.
    Response--Using national default BCFs for water quality criteria 
began in 1980 and is necessary to ensure that criteria related to human 
ingestion of fish and shellfish will be protective of the consumer 
human populations who eat them. The BCF values determined for the water 
quality criteria represented the best scientific information available 
at the time. BCFs for nonionic organic chemicals that were determined 
from Veith et al. (1979) are based on a statistically significant 
correlation between experimentally determined chemical concentrations 
in water and fish tissues. We describe in detail the scientific basis 
for applying this data in the 1980 Ambient Water Quality Criteria 
National Guidelines (45 FR 79347).
    EPA recognizes that many scientific advances have occurred in the 
area of bioaccumulation since it published the 1980 Methodology. As a 
result, EPA has revised the bioaccumulation portion of the 1980 
Methodology to reflect the current state of science and to improve 
accuracy in assessing bioaccumulation for setting 304(a) criteria. 
EPA's Methodology for Deriving Ambient Water Quality Criteria for 
Protection of Human Health (2000) ( 65 FR 66444; hereafter referred to 
as the ``2000 Methodology'') contains the revised procedures for 
incorporating bioaccumulation in ambient water quality criteria (AWQC) 
and a summary of the key changes. EPA will publish more detailed 
information on the BAF

[[Page 75512]]

methodology in the near future (Technical Support Document Volume 2: 
Development of National Bioaccumulation Factors). We developed the 
approaches to deriving bioaccumulation factors and applying them in 
AWQC presented from a process that included extensive review from EPA's 
Science Advisory Board, peer review workshops, and stakeholder meetings 
(65 FR 6644).
    EPA's framework deriving bioaccumulation factors is designed to 
account for chemical, biological and ecological attributes. For 
example, we provide separate procedures for deriving national BAFs 
depending on the type of chemical (i.e., nonionic organic, ionic 
organic, inorganic and organometallic). More specifically, EPA's 
framework recognizes that the derivation of BAFs for organometallic 
chemicals differs in several ways from procedures for organic 
chemicals. For example, there are no generic bioaccumulation models 
that can be used to predict BAFs for organometallic chemicals as a 
whole; therefore, EPA's preferred approach for deriving national BAFs 
for such chemicals is to use empirical field data.
    EPA took this approach in deriving draft national BAFs for 
methylmercury (see Water Quality Criterion for the Protection of Human 
Health: Methylmercury (EPA-823-R-01-001, January 2001)). We found the 
empirically-derived draft methylmercury BAFs to be variable, reflecting 
the influences of various biotic factors and abiotic factors on 
methylmercury bioaccumulation that were not well understood at that 
time. EPA acknowledged that these factors resulted in uncertainty as to 
the ability of the BAFs to accurately predict bioaccumulation of 
methylmercury across the waters of the United States. However, in this 
same document, EPA noted that this is not the case for other highly 
bioaccumulative pollutants (i.e., non-organometallics). For such 
pollutants, EPA has methods that improve the predictive capability of 
empirically-derived or model-predicted BAFs.
    When it conducts a full re-evaluation of the human health water 
quality criteria for the chemicals included in this Notice, EPA will 
evaluate the best available evidence concerning BAF values. EPA will 
develop national BAF values to the extent possible given the best 
available data at the time. Where derivation of National BAFs is not 
possible, EPA's 2000 Methodology encourages States and authorized 
Tribes to derive BAFs that are specific to regions or waterbodies as 
appropriate.
    e. Scientific validity of using cancer potency factors or RfDs to 
define thresholds of unacceptable adverse effects is questionable.
    Scientific view--One submitter questioned the scientific validity 
of using cancer potency factors or RfDs to define thresholds of 
unacceptable adverse effects. EPA should explicitly address the 
``scientific gray area'' that exists between human health effects and 
RfDs and a benchmark dose or the lowest observed effect level on which 
an RfD might be based.
    Response--As discussed in Methodology for Deriving Ambient Water 
Quality Criteria for the Protection of Human Health (2000) (EPA-822-B-
00-004, October 2000), human health water quality criteria are designed 
to minimize the risk of adverse effects to humans from chronic 
(lifetime) exposure to substances through the ingestion of drinking 
water and eating fish from surface waters.
    The water quality criteria are based on chronic health effects data 
(both cancer and noncancer). However, the criteria also are intended to 
protect against adverse effects not only for the general population 
over a lifetime of exposure, but also for special populations (e.g., 
sports fishers, children, elderly) who have an increased risk of 
receiving a dose that would elicit adverse effects due to their high 
water- or fish-intake rates or their biological sensitivities. Neither 
the benchmark dose nor a lowest observed effects level represent a 
``threshold'' for response in the human or animal populations. Instead, 
those values typically are associated with a small proportional 
response level for the populations in question. EPA acknowledges the 
possibility that other populations might be more sensitive than those 
examined.
    The Agency fully documents the derivation of its cancer potency 
factors and RfDs in IRIS. Those values were derived using the Agency 
guidelines for risk assessment, extensive peer review, and the best 
available information at the time the values were developed. The Agency 
continues to review and update the human health effects data in IRIS to 
ensure it considers the most current literature. That process, however, 
takes time. The IRIS Web (http://www.epa.gov/iris/) site describes 
EPA's policy on the ``scientific gray areas'' that reflect the use of 
uncertainty factors to cover certain types of data gaps.
2. EPA Should Adopt a Fish Tissue-Based Criteria in Lieu of the 
Proposed Water Column Criteria
    Scientific view--EPA should derive fish tissue criteria, rather 
than water column concentrations, for the 15 compounds to avoid the 
scientific deficiencies related to the inappropriate use of BCFs and 
BAFs. Compliance monitoring and site-specific adjustments also are 
simplified when criteria are based on fish-tissue measurements in lieu 
of water column criteria. The submitter also requested a table of the 
intermediate fish tissue levels used in (or derived from) the 
calculation of the proposed water column criteria.
    Response--For the most part, EPA has published water column 
concentrations as their recommended water quality criteria values for 
protection of human health. The recent exception being the fish tissue 
concentration for methylmercury (see 66 FR 1344, January 8, 2001). When 
the new methylmercury criterion was published, EPA withdrew its 
previous ambient human health water quality criteria for mercury as the 
recommended section 304(a) water quality criteria. At that time, EPA 
also recognized that this approach differed from the traditional water 
column criteria approach and suggested ways to relate the fish and 
shellfish tissue criterion to concentrations of methylmercury in the 
water column. We must relate tissue concentrations to water column 
concentrations in order to use the criterion to establish discharge 
limits for point sources. Fish tissue criteria can be developed and 
potentially simplify compliance monitoring and site-specific 
adjustments, yet this does not eliminate the need to develop BAFs.
    Using national BAFs is a scientifically valid approach to deriving 
national water quality criteria. EPA encourages States and authorized 
Tribes to develop BAFs based on field-measured data from local/regional 
fish, whenever possible, when developing their own water quality 
standards.
    The 15 revised human health criteria do not incorporate BAFs, a 
component of the new methodology; rather, the revised criteria are 
based on previously-developed BCFs. Thus, we have not estimated 
intermediate fish tissue concentrations.
3. EPA Should Provide All Numeric Factors Used in the Derivation of the 
Proposed Criteria
    Scientific view--One submitter stated that EPA should provide 
information and references for all components needed to calculate the 
proposed criteria, including Kow values and food chain 
multipliers.
    Response--EPA included all basic parameters necessary for deriving 
the criteria in the December 27, 2002,

[[Page 75513]]

Federal Register notice announcing the proposed revisions (67 FR 
79091). These parameters include: BCFs, fish consumption rate, body 
weight, reference dose or cancer potency factor, and relative source 
contribution. You can find information relevant to the derivation of 
these basic parameters (e.g., Kow values used in the 
derivation of BCFs) in other data sources such as EPA's criteria 
documents.
    The revised human health criteria EPA developed use the BCF values 
derived from the 1980 Ambient Water Quality Criteria National 
Guidelines (45 FR 79347). We did not use food chain multipliers in the 
1980 Methodology and, therefore, did not use them in deriving the 
proposed criteria. Rather, the proposed criteria rely on previously-
derived BCFs which may have been derived from lab or field studies. 
Even though these BCFs emphasize bioconcentration, in some instances 
they may reflect trophic level transfers but not through the use of 
food chain multipliers.
4. EPA Should Publish All Proposed Changes to the Human Health Water 
Quality Criteria in the Federal Register
    Scientific view--One submitter stated that EPA should publish all 
proposed changes to the human health water quality criteria in the 
Federal Register. In this way, dischargers and other affected parties 
will be aware of upcoming changes that will affect permits and other 
activities.
    Response--EPA described its process for publishing revised criteria 
in National Recommended Water Quality Criteria--Correction (64 FR 
19781; or EPA 822-Z-99-001) and the Federal Register notice for the 
final methodology (65 FR 66444). EPA specifically stated that, when 
making minor revisions to existing criteria based on new information 
about individual components of the criteria, the Agency will publish 
the recalculated criteria directly as the Agency's national recommended 
water quality criteria. This is a reasonable and efficient way to more 
frequently publish revised section 304(a) criteria. Based on this 
approach, EPA partially revised 83 national recommended water quality 
criteria for the protection of human health. EPA published these 
updated national recommended water quality criteria in a compilation 
entitled National Recommended Water Quality Criteria: 2002 (EPA-822-02-
047).
    EPA also revised 15 more national recommended water quality 
criteria for the protection of human health. Although the revision of 
these criteria represent a partial update of the section 304(a) 
criteria, EPA decided to solicit scientific views on the criteria 
because applying the new methodology resulted in significant changes 
(67 FR 79091; December 27, 2002).
5. The Criteria Compilation Should Clearly Articulate That the 
Recommended Criteria Are Available for States To Use, as Appropriate, 
in Adopting Their Water Quality Criteria
    Scientific view--A submitter stated that the 2000 Human Health 
Methodology encourages States to use local fish consumption rates to 
establish site-specific criteria rather than default fish consumption 
rates. However, without site-specific fish consumption rates, States 
cannot develop the most accurate criteria. Therefore, the criteria 
compilation should clearly articulate that States are not required to 
adopt EPA's recommended criteria, but that EPA's recommended criteria 
are available, as appropriate, when adopting criteria.
    Response--CWA section 304(a)(1) requires EPA to develop and publish 
criteria for water quality that accurately reflect the latest 
scientific knowledge. Under this authority, EPA publishes national 
criteria that are recommendations to States and authorized Tribes in 
adopting water quality standards. These criteria are based on national 
default parameters, such as fish ingestion rates. Nevertheless, as 
stated in the National Recommended Water Quality Criteria: 2002 (EPA-
822-02-047) compilation, ``State and Tribal decision-makers have the 
discretion to adopt approaches on a case-by-case basis that differ from 
this guidance when appropriate.'' In addition, the 2002 compilation 
document explains that:

    ``States and authorized Tribes have four options when adopting 
water quality criteria for which EPA has published section 304(a) 
criteria. They can: (1) Establish numerical values based on 
recommended section 304(a) criteria; (2) adopt section 304(a) 
criteria modified to reflect site-specific conditions; (3) adopt 
criteria derived using other scientifically defensible methods; or 
(4) establish narrative criteria when numeric criteria cannot be 
determined (40 CFR 131.11).''

    Thus, EPA clearly stated that States and authorized Tribes are not 
required to adopt EPA national recommended water quality criteria, and 
that States and authorized Tribes have the discretion to derive 
criteria based on site-specific considerations such as local fish 
consumption rates.
6. Vinyl Chloride
    a. The proposed human health water quality criteria for vinyl 
chloride are too low.
    Scientific view--A submitter indicated that improper methods, 
overly conservative assumptions, and data quality deficiencies result 
in the proposed human health water quality criteria for vinyl chloride 
being too low.
    Response--In deriving the water quality criteria for vinyl 
chloride, EPA applied the 2000 Human Health Methodology. In developing 
this methodology, EPA solicited and incorporated input from many 
sources, including the EPA Science Advisory Board, several peer review 
workshops, and the public. EPA believes that the resulting methodology 
accurately reflects the latest scientific knowledge on the kind and 
extent of all identifiable effects on health and welfare that can be 
expected when pollutants are present in any body of water. Thus, the 
human health water quality criteria for vinyl chloride accurately 
reflect the relationship between vinyl chloride concentrations and 
human health effects.
    The recommended water quality criteria for vinyl chloride are 
guidance for States and authorized Tribes to establish water quality 
standards. State and Tribal decision-makers have the discretion to 
adopt approaches on a case-by-case basis that differ from this guidance 
when appropriate.
    b. EPA should use a central estimate as a point of departure in 
deriving vinyl chloride criteria.
    Scientific view--Two submitters stated that the revised vinyl 
chloride human health water quality criteria for consumption of water 
and organism and consumption of organisms only are too low because EPA 
used overly conservative assumptions in their derivation. Risk-specific 
doses derived based on linear low-dose extrapolations using the lower 
95 percent confidence limit on a dose associated with a 10 percent 
extra risk, or, LED10, as the point of departure should not 
be used to derive criteria. Rather, risk-specific doses based on a 
central estimate, such as a dose associated with a 10 percent extra 
risk, or ED10, should be used as a point of departure.
    EPA's rationale for using the LED10 as the point of 
departure for model-based dose-response extrapolations in the 1996 
proposed guidelines for carcinogen risk assessment is very weak. EPA 
did not hear the advice from peer review workshops on benchmark dose 
and the proposed cancer guidelines

[[Page 75514]]

recommending the use a of central estimate (ED10) point of 
departure.
    EPA's decision to use an LED10, as opposed to an 
ED10, in deriving revised human health criteria for vinyl 
chloride is inconsistent with EPA's Guidelines for Ensuring and 
Maximizing the Quality, Objectivity, Utility, and Integrity of 
Information Disseminated by the Environmental Protection Agency and the 
Information Quality Act (IQA). EPA's science policy decision to use the 
LED10, instead of the ED10, introduces 
significant uncertainty in the risk assessment that underlies the water 
quality criteria derivations, which is in violation of the IQA. The 
submitter requested that we correct this information.
    Response--The 2000 Human Health Methodology includes toxicological 
and exposure assessment parameters derived from scientific analysis, 
science policy, and risk management decisions, including the 1986 
cancer guidelines [see Guidelines for Carcinogen Risk Assessment (51 FR 
33992)] and principles from the 1999 draft revised cancer guidelines 
[see 1999 Guidelines for Carcinogenic Risk Assessment--Review Draft 
(NCEA-F-0644, July 1999)]. These principles arise from scientific 
discoveries about cancer made in the last 15 years and from EPA policy 
supporting full characterization of hazard and risk for both the 
general population and potentially sensitive groups like children.
    In particular, EPA's 1999 draft revised cancer guidelines gave a 
rationale for selecting point of departures (PODs). For quantitative 
modeling of dose-response relationships in the observed range, the 
guidelines recommend calculating the lower 95 percent confidence limit 
on a dose associated with an estimated 10 percent increased tumor or 
relevant non-tumor response (LED10). The estimate of the 
LED10 is used as the point of departure (POD) for low-dose 
extrapolation. This standard point of departure (LED10) is 
adopted as a matter of science policy to remain as consistent and 
comparable across different studies. It is also a convenient comparison 
point for noncancer endpoints. The rationale for using the 
LED10 is that a 10 percent response is at or just below the 
limit of sensitivity for discerning a statistically significant tumor 
response in most long-term rodent studies and is also within the 
observed range for other toxicity studies. Using the lower limit takes 
experimental variability and sample size into account. Note that use of 
the lower 95 percent confidence limit on the ED10 implies 
that, given the experimental parameters (e.g., sample size, variation 
in response) of the study being used, there is a five percent chance or 
less that the ``true'' ED10 would be lower than the 
LED10. For well-conducted studies with large numbers of 
animals, relatively close dose spacing, and little inherent variability 
in the animal responses, LED10 values will be close to the 
central estimate of the ED10 value. For studies that include 
smaller numbers of animals, wider dose spacing, and more variable 
responses in replicates at the same dose, the LED10 value 
will be further removed from the ED10 value. It is part of 
EPA's science policy to use the lower bound of a 95 percent confidence 
interval around a preferred value (e.g., central estimate of the 
ED10) as a point of departure to ensure that the criterion 
will be adequately protective, that is, that the experimental 
uncertainty is small (a few percent or less). The EPA's IRIS cancer 
assessment of vinyl chloride uses the LED10 as the POD. 
EPA's Guidelines for Ensuring and Maximizing the Quality, Objectivity, 
Utility, and Integrity of Information Disseminated by the Environmental 
Protection Agency (EPA/260R-02-008, October 2002) indicated that EPA 
intends to specify the central estimate of human health risk when it is 
available. The ED10 (central estimate) for vinyl chloride is 
not presented in IRIS. More recent IRIS entries do include the central 
estimate, but this was not the policy at the time vinyl chloride was 
completed. The requirement for its inclusion was instituted in the 2003 
Standard Operating Procedures for IRIS.
    c. The vinyl chloride MCL is a more appropriate benchmark level.
    Scientific view--A submitter indicated that the current maximum 
contaminant level (MCL) for vinyl chloride of two parts per billion 
(ppb) which was developed under the Safe Drinking Water Act (SDWA) is a 
more appropriate benchmark level.
    Response--The human health water quality criteria developed under 
CWA section 304(a) are based solely on data and scientific judgments 
about the relationship between pollutant concentrations and 
environmental and human health effects. Unlike the MCLs, the criteria 
do not consider economic impacts or the technological feasibility of 
meeting the chemical concentrations in ambient water. Thus, MCLs are 
not considered counterparts to water quality criteria.
    d. The vinyl chloride water quality criterion for consumption of 
organisms should only be based on incidental ingestion of non-potable, 
recreational waters.
    Scientific view--A submitter stated that the revised vinyl chloride 
human health criteria for potable water was derived based on the 
assumption that people would drink two liters of surface water each day 
over a lifetime. Thus, surface water is effectively considered a public 
water supply. However, if the intended use of the water quality 
criteria is to set NPDES limits for potable waters not being used as 
public water supplies, then the water consumption assumption is overly 
conservative. Such waters serve only as recreational or occasional use 
water bodies, so that a value for incidental water ingestion would be 
more appropriate. For regulatory consistency, the water quality 
criteria for vinyl chloride for potable water supplies should be the 
same as the MCL.
    Response--As required by CWA section 304(a), EPA develops water 
quality criteria that reflect the latest scientific knowledge on 
effects of pollutants on human health. States and authorized Tribes use 
the Agency's recommended section 304(a) water quality criteria to adopt 
enforceable water quality standards, including designating uses of a 
water body consistent with CWA section 101(a) (e.g., public water 
supply, fishing, recreation). In developing the 2000 Human Health 
Methodology, we made assumptions about exposure to contamination from 
consuming surface waters of the U.S. Our assumptions ensure that, if 
criteria are met in a water body designated with the uses specified in 
section 101(a), people can safely consume water from that water body. 
In order to ensure this, it is necessary to assume that all of the 
consumed water is taken from water bodies at the criteria level (i.e., 
contaminated to the maximum safe level).
    The designated use inherent in the submitter's example is drinking 
water (potable water), even though the particular water body might not 
be used that way at the moment. Thus, the main issue in the view 
relates to the State's (or authorized Tribe's) assignment of designated 
use, not to numeric values for the national ambient water quality 
criteria for vinyl chloride.
    Again, the human health water quality criteria developed under CWA 
section 304(a) are based solely on data and scientific judgments on the 
relationship between pollutant concentrations and environmental and 
human health effects. Unlike the MCLs, the criteria do not consider 
economic impacts or the technological feasibility of meeting the 
chemical concentrations in ambient water. MCLs are not counterparts to 
water quality criteria.
    e. EPA's BCF for vinyl chloride is overstated and its water quality 
criterion

[[Page 75515]]

for consumption of organisms should only be based on incidental 
ingestion of non-potable, recreational waters.
    Scientific view--One submitter stated that EPA derived its vinyl 
chloride human health criterion for consumption of organisms only using 
a bioconcentration factor (BCF) of 1.17. The submitter believes that 
this BCF is overstated because:
    (1) This value is based on the assumption of equilibrium conditions 
between water and an organisms tissue, which is not the case because 
the compound is highly metabolized;
    (2) the high volatility of vinyl chloride would contribute to its 
depuration during processing or cooking;
    (3) the portions of the fish most likely to contain the compound, 
(e.g., skin and fat) are not typically consumed by humans; and
    (4) cooking would result in further off-gasing or destruction of 
the chemical.
    Thus, we expect the potential for humans consuming aquatic 
organisms to be exposed to vinyl chloride to be negligible. Moreover, 
vinyl chloride does not biomagnify, and higher tropic level organisms 
consumed by humans would not contain elevated levels of vinyl chloride. 
EPA should derive its vinyl chloride criteria for consumption of 
organisms only based on exposure from incidental ingestion of non-
potable recreational waters only.
    Response--In updating its human health water quality criteria for 
vinyl chloride, EPA used the BCF derived from the 1980 Ambient Water 
Quality Criteria National Guidelines (45 FR 79347). The submitter is 
correct that, if a contaminant is readily metabolized in fish, the 
actual BCF might be less than estimated using the KLEDow 
method. EPA thanks the submitter for the information and will consider 
it when the Agency comprehensively updates the vinyl chloride criterion 
document to incorporate the BAF derivation procedures described in the 
2000 Human Health Methodology.

C. Where Other Views Submitted?

    We received a number of views on criteria that EPA was not 
revising, or the views expressed were not related to the science 
supporting the criteria derivations. EPA did not prepare responses 
addressing these views.

    Dated: December 23, 2003.
Geoffrey H. Grubbs,
Director, Office of Science and Technology.
[FR Doc. 03-32211 Filed 12-30-03; 8:45 am]
BILLING CODE 6560-50-P