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National Recommended Water Quality Criteria
for the Protection of Human Health
[Federal Register: December 31, 2003 (Volume 68, Number 250)]
[Notices]
[Page 75507-75515]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr31de03-71]
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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;
roberts.cindy@epa.gov.
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:
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Category Examples of interested entities
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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.
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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
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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.
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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
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