Water Quality Standards; Establishment of Numeric Criteria for Priority Toxic Pollutants; States' ComplianceRevision of Polychlorinated Biphenyls (PCBs) Criteria
Federal RegisterNov 9, 1999
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SUMMARY: The Clean Water Act (CWA) requires States to adopt numeric
criteria for priority toxic pollutants for which EPA has published
criteria guidance if the discharge or presence of such pollutants could
reasonably be expected to interfere with the designated uses of the
State's waters. In 1992, EPA promulgated the National Toxics Rule (NTR)
establishing numeric water quality criteria for toxic pollutants in
fourteen States and jurisdictions to protect human health and aquatic
life. These States and jurisdictions had not adopted sufficient
chemical-specific, numeric criteria for toxic pollutants necessary to
comply with the Clean Water Act.
Among the criteria promulgated in the NTR were human health and
aquatic life water quality criteria for polychlorinated biphenyls
(PCBs). Today, EPA is issuing revisions to the human health water
quality criteria for PCBs in the NTR, based on the Agency's
reassessment of the cancer potency of PCBs. The revised criteria will
apply in: Alaska, District of Columbia, Kansas, Michigan, Nevada, New
Jersey, Puerto Rico, Rhode Island, Vermont and Washington.
EFFECTIVE DATE: This rule shall be effective December 9, 1999.
ADDRESSES: The public may inspect the administrative record for this
rulemaking and all public comments received on the proposed rule at the
Water Docket, East Tower Basement, USEPA, 401 M St., S.W., Washington,
D.C. The record is available for inspection from 9:00 to 4:00 p.m.,
Monday through Friday, excluding legal holidays. Please call (202) 260-
3027 to schedule an appointment.
FOR FURTHER INFORMATION CONTACT: Cindy Roberts, Health and Ecological
Criteria Division (4304), Office of Science and Technology, Office of
Water, U.S. Environmental Protection Agency, 401 M Street, S.W.,
Washington, D.C. 20460, (202) 260-2787.
SUPPLEMENTARY INFORMATION:
A. Who is potentially affected by the National Toxics Rule?
B. What is the National Toxics Rule?
C. Why is EPA revising the National Toxics Rule?
D. Why did EPA change the human health criteria for PCBs?
E. Can an NTR State develop site-specific criteria?
F. Response to Public Comments
G. References
H. Regulatory Assessment Requirements
A. Who Is Potentially Affected by the National Toxics Rule?
Dischargers of PCBs to waters of the United States in States and
jurisdictions subject to the National Toxics Rule (NTR) could be
affected by this rule. National Toxics Rule States include: Alaska,
District of Columbia, Kansas, Michigan, Nevada, New Jersey, Puerto
Rico, Rhode Island, Vermont and Washington. These dischargers may be
affected since water quality criteria are part of water quality
standards that, in turn, are used in developing National Pollutant
Discharge Elimination System (NPDES) permit limits. Categories of
pollutant dischargers that may ultimately be affected include:
------------------------------------------------------------------------
Examples of potentially
Category affected entities
------------------------------------------------------------------------
Industry.................................. Industries discharging to
waters of NTR States and
jurisdictions.
Municipalities............................ Publicly-owned treatment
works discharging to waters
of NTR States and
jurisdictions.
------------------------------------------------------------------------
This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be affected by this
action. This table lists the types of entities that EPA is now aware
could potentially be affected by this action. Other types of entities
not listed in the table could also be affected if PCBs are found in
their pollutant discharges. To determine whether your facility,
company, business, or organization may be affected by this action, you
should carefully examine the applicability criteria in Sec. 131.36 (d)
of title 40 of the Code of Federal Regulations. If you have questions
regarding the applicability of this action to a particular entity
consult the person listed in the preceding FOR FURTHER INFORMATION
CONTACT section.
B. What Is the National Toxics Rule?
The Clean Water Act (CWA) requires States to adopt numeric criteria
for priority toxic pollutants if EPA has published criteria guidance
and if the discharge or presence of these pollutants could reasonably
be expected to interfere with the designated uses of the State's
waters. In 1992, EPA ``promulgated'' or put into force of law, the
National Toxics Rule (NTR) establishing numeric water quality criteria
for toxic pollutants in fourteen States and jurisdictions to protect
human health and aquatic life (57 FR 60848, December 22, 1992,
incorporated in the Code of Federal Regulations at 40 CFR 131.36).
These States and jurisdictions had not adopted adequate numeric
criteria for pollutants necessary to comply with the Clean Water Act.
C. Why Is EPA Revising the National Toxics Rule?
Among the criteria promulgated in the NTR were PCB criteria to
protect human health. These criteria were based on procedures issued in
1980 (``Guidelines and Methodology Used in the Preparation of Health
Effects Assessment Chapters of the Consent Decree Water Criteria
Documents,'' 45 FR 79347, November 28, 1980 or ``Human Health
Guidelines'').
General Electric Company (GE) and the American Forest and Paper
Association, Inc. challenged a number of aspects of the NTR, including
the human health water quality criteria for PCBs. (American Forest and
Paper Ass'n. Inc. et al. v. U.S. EPA (Consolidated Case No. 93-0694
(RMU) D.D.C.). In particular, the plaintiffs objected to EPA's
application of its cancer risk assessment methodology to its evaluation
of the carcinogenicity of PCBs and the Agency's evaluation of various
scientific studies relevant to the cancer risk posed by PCBs. EPA had a
number of activities underway that could have led to a revision of the
criteria, including reassessment of the cancer potency of PCBs (the
``cancer reassessment''), revision of the methodology to derive human
health water quality criteria, and revision of the cancer guidelines.
EPA and the plaintiffs entered into a partial settlement agreement in
which EPA agreed, among other things, to a schedule for completing the
cancer reassessment. See ``Partial Settlement Agreement,'' Consolidated
Case No. 93-0694 RMU, D.D.C, signed November 7, 1995.
EPA also agreed that within 18 months of the issuance of the final
cancer reassessment, the Agency would
[[Page 61183]]
propose a revision to the NTR human health criteria for PCBs, or
publish a Federal Register notice explaining why it was not revising
the NTR criteria. EPA completed the cancer reassessment in September
1996, (``PCBs: Cancer Dose-Response Assessment and Applications to
Environmental Mixtures'' (EPA 600/P-96/001F). This report shows how
information on toxicity, tendencies and environmental processes can be
used together to evaluate health risks from PCBs in the environment.
EPA also considered several issues identified by the plaintiffs. In
accordance with the terms outlined in the partial settlement agreement,
EPA proposed revisions to the NTR human health criteria for PCBs on
March 27, 1998 (63 FR 16182, April 2, 1998). In today's document, EPA
is amending the PCBs human health criteria in the NTR.
D. Why Did EPA Change the Human Health Criteria for PCBs?
What Are PCBs and Why are They a Problem in the Environment?
Polychlorinated biphenyls or PCBs are a group of chemicals that
contain 209 individual compounds known as ``congeners.'' Commercial
PCBs are mixtures of congeners that differ in their chlorine content.
Different mixtures can take on forms ranging from oily liquids to waxy
solids. Although their chemical properties vary widely, different
mixtures have many common PCB congeners. Because of their flame
retardant properties, chemical stability, and insulating properties,
commercial PCB mixtures were used in many industrial applications.
These chemical properties also contribute to the slow degradation of
PCBs after they are released into the environment. Because of evidence
of persistence and harmful effects, domestic manufacture of commercial
mixtures was stopped in 1977; existing PCBs continue in use, primarily
in electrical capacitors and transformers.
In the environment, PCBs occur as mixtures of congeners, but their
composition differs from the commercial mixtures. This is because after
release into the environment, the composition of PCB mixtures changes
over time through partitioning, chemical transformation and
preferential bioaccumulation of certain congeners. Partitioning is the
separation of a chemical into different environmental media, such as
fish tissue or sediments. Preferential bioaccumulation is the affinity
for a congener to accumulate in one type of environmental media over
another. Some PCB congeners can accumulate in living organisms. PCBs
are widespread in the environment because of past contamination, and
humans are exposed through multiple pathways including ambient air,
drinking water, and diet.
How Were the Criteria for PCBs Developed?
The PCBs criteria included in the NTR were based on a single dose-
response slope factor (7.7 per mg/kg-d average lifetime exposure); this
was the value included in EPA's Integrated Risk Information System
(IRIS, www.epa.gov/ngispgm3/iris/irisdat) at that time. A slope factor
is a means of indicating the relevant potency of a cancer causing
chemical. This slope factor value was derived from a rat feeding study
by Norback and Weltman (1985), one of several studies of a commercial
mixture called Aroclor 1260. Because there was no agreed-upon basis for
reflecting differences among environmental mixtures, the 7.7 per mg/kg-
d slope factor was used for all PCBs and PCB mixtures. As noted above,
GE challenged the PCB criteria, disagreeing with EPA's use of this
slope factor to calculate the NTR human health criteria for PCBs on
several grounds, including that the Norback and Weltman study had been
reevaluated. GE argued that if the reevaluated results had been used,
the cancer potency factor would have been significantly lower. EPA
agreed to complete a reassessment of the cancer potency factor for PCBs
.
What's Different About the New Cancer Reassessment?
EPA considered a number of different approaches for its
reassessment, and adopted an approach that distinguishes among PCB
mixtures by using information on environmental processes that can
decrease or increase toxic potency of an environmental mixture. EPA's
new assessment considered all cancer studies (which used commercial
mixtures only) including a new study of four different commercial
mixtures (Aroclors) that strengthens the case that all PCBs mixtures
can cause cancer. EPA used this information to develop a range of dose
response slopes, changing the single-dose cancer potency factor of 7.7
per mg/kg-d to a range from 0.07 per mg/kg-d (lowest risk and
persistence) to 2.0 per mg/kg-d (high risk and persistence). It is
noteworthy that bioaccumulated PCBs appear to be more toxic than
commercial PCBs and appear to be more persistent in the body. The
reassessment uses information on environmental processes to provide
guidance on choosing an appropriate slope for representative classes of
environmental mixtures and different exposure pathways.
The guidance matches slope values from the range to exposure
pathway (e.g., food chain) by using a ``tiered approach'' which
attributes higher risk to exposure through the food chain compared to
other exposures. Bioaccumulation through the food chain tends to
concentrate certain highly chlorinated congeners which are often among
the most toxic and persistent. Persistence in the body can enhance the
opportunity for PCB congeners to express toxicity (Safe, 1994). Studies
indicate that the major pathway of exposure to persistent toxic
substances such as PCBs is through food (i.e., contaminated fish and
shellfish consumption). Because it considers consumption of
contaminated fish to be the dominant source of PCB exposure, EPA
proposed and has decided to use a cancer potency factor of 2 per mg/kg-
d, the ``upper bound'' potency factor reflecting high risk and
persistence, to calculate the revised human health criteria for PCBs.
This upper bound slope factor of 2 per mg/kg-d is also used to assess
increased cancer risks associated with early life exposure to PCBs.
The cancer reassessment was subject to peer review by a group of
experts from outside the Agency. See ``Report on Peer Review Workshop
on PCBs: Cancer-Dose Response Assessment and Application to
Environmental Mixtures,'' May 1996.
How Are Today's Human Health Criteria for PCBs Calculated?
Using the cancer potency factor of 2 per mg/kg-d the human health
criterion (HHC) for organism and water consumption is as follows:
[GRAPHIC] [TIFF OMITTED] TR09NO99.000
[[Page 61184]]
Where:
RF = Risk Factor = 1 x 10 (-6)
BW = Body Weight = 70 kg
q1* = Cancer slope factor = 2 per mg/kg-d
WC = Water Consumption = 2 L/day
FC = Fish and Shellfish Consumption = 0.0065 kg/day
BCF = Bioconcentration Factor = 31,200
the HHC (μg/l) = 0.00017 μg/L (rounded to two
significant digits).
Following is the calculation of the human health criterion for
organism only consumption:
[GRAPHIC] [TIFF OMITTED] TR09NO99.001
Where:
RF = Risk Factor = 1 x 10 (-6)
BW = Body Weight = 70 kg
q1* = Cancer slope factor = 2 per mg/kg-d
FC = Total Fish and Shellfish Consumption per Day = 0.0065 kg/day
BCF = Bioconcentration Factor = 31,200
the HHC (μg/l) = 0.00017 μg/L (rounded to two
significant digits).
The criteria are both equal to 0.00017 μg/l and apply to
total PCBs. See ``PCBs: Cancer Dose Response Assessment and Application
to Environmental Mixtures'' (EPA 600/9-96-001F). The body weight and
water consumption factors are discussed in the Human Health Guidelines
(``Guidelines and Methodology Used in the Preparation of Health Effects
Assessment Chapters of the Consent Decree Water Criteria Documents,''
45 FR 79347, November 28, 1980). The BCF is discussed in the 304(a)
criteria guidance document for PCBs (``Ambient Water Quality Criteria
for Polychlorinated Biphenyls,'' EPA 440/5-80-068) (1980).
In developing today's criteria EPA relied on the currently
available Human Health Guidelines (45 FR 79347, November 28, 1980).
However, EPA recently proposed revisions to the methodology it uses to
derive water quality criteria for human health (63 FR 43755, August 14,
1998). When the proposed revisions are finalized, EPA expects to
recommend the use of bioaccumulation factors (BAFs) in place of
bioconcentration factors (BCFs). For certain chemicals including PCBs,
the revised methodology would emphasize the assessment of
bioaccumulation (i.e., uptake from water, food, sediments) over
bioconcentration (i.e., uptake from water only). The change outlined
above may result in a significant numeric change in the ambient water
quality criteria for PCBs. For PCBs and other bioaccumulative
chemicals, BAFs may be developed which are orders of magnitude greater
than the BCFs developed in 1980. This would likely result in a
criterion which is orders of magnitude more stringent, if all other
parameters (such as q1*s) remain constant.
Why Are the Criteria Now Expressed as Total PCBs?
In its 1998 proposal, EPA offered a different approach for
expressing human health criteria for PCBs. Human health criteria would
no longer be based on individual Aroclors, but rather on total PCBs
concentrations. In the environment, PCBs occur as mixtures of congeners
but these are different in composition than commercial mixtures
(Aroclors). This is because PCB mixtures can change over time through
partitioning among different environmental media (e.g., water,
sediment), by chemically transforming or preferentially
bioaccumulating. Therefore, it can be imprecise and inappropriate to
characterize environmental mixtures in terms of Aroclors (EPA, 1996).
It is the Agency's view that expressing the criteria in terms of total
PCBs rather than individual Aroclors better reflects current scientific
thought (See: ``PCBs: Cancer Dose Response Assessment and Application
to Environmental Mixtures,'' ``Assessing the cancer risks from
environmental PCBs'' (Cogliano, 1998) and the proposed PCBs criteria in
the California Toxics Rule, 62 FR 42160, August 5, 1997).
E. Can an NTR State Develop Site-Specific Criteria
EPA prefers that States maintain primacy, revise their own
standards, and achieve full compliance, but in order to achieve
primacy, States must first be removed from the NTR. Removal of a State
from the NTR requires rulemaking by EPA according to the requirements
of the Administrative Procedure Act (5 U.S.C. 551 et seq.). For
example, both Rhode Island and Vermont have adopted criteria, including
criteria for PCBs, required by CWA 303(c)(2)(b). EPA approved the state
adoptions and will be initiating action to remove both Rhode Island and
Vermont from the NTR in the near future. Pending completion of this
action, nothing in this rule preempts these States' authority to
implement any more stringent State criteria for PCBs. (See section 510
of CWA).
A State cannot derive site-specific criteria for pollutants for
which EPA has established standards in the National Toxics Rule.
Promulgation of the NTR removed most of the flexibility available to
the affected States for modifying their standards on a discharger-
specific or stream-specific basis. For example, site-specific criteria
for human health are precluded for NTR States unless there is a Federal
rulemaking in that State to change the Federal rule for that State, or
unless the State adopts a more stringent criteria pursuant to CWA
section 510, which as a practical matter would override the less
stringent NTR criteria.
EPA will withdraw the promulgated criteria in the NTR by rule
without a notice and comment, when a State adopts standards no less
stringent than the NTR (i.e., standards which provide, at least,
equivalent environmental protection). However, if a State adopts
standards for toxics which are less stringent than the Federal rule
but, in the Agency's judgment fully meet the requirements of the Act,
EPA will propose to withdraw the NTR criteria with a notice of proposed
rulemaking and provide for public participation. Thereafter the Agency
will issue a final rule.
A State may want to develop site-specific human health criteria for
PCBs when exposure information indicates that an alternate cancer slope
factor is appropriate. As mentioned above, EPA's 1996 cancer assessment
for PCBs uses information on environmental processes to provide
guidance on choosing an appropriate cancer slope factor from a range of
slope factors. An ``upper bound'' potency factor, such as the 2 per mg/
kg-d used in this rule, is appropriate for food chain exposure,
sediment or soil ingestion, and dust or aerosol inhalation pathways.
These are exposure pathways where environmental processes tend to
increase risk. Lower potencies are appropriate for ingestion of water-
soluble congeners or inhalation of evaporated congeners. These are
pathways where environmental processes tend to decrease risk (EPA,
1996).
F. Response to Public Comments
As noted above, EPA published proposed revisions of the PCB human
health criteria in 1998. EPA received several comments from the public
and significant comments are addressed in this section.
1. One commenter asked for more time in which to prepare additional
materials for submission.
Response: EPA did not agree that revisions of the PCB criteria
should be delayed based upon the expectations of future analyses of
epidemiological data. EPA realizes that scientific information is
constantly evolving. Additional research is always being done and test
[[Page 61185]]
methods and theories improve. There can be a long lag time between
conducting the research, analyzing data, issuing a criteria or risk
assessment for peer review, incorporating peer review comments and
working through the State or Federal administrative processes to adopt
water quality standards. There comes a point in this process, where the
administering agencies, both EPA and the States, have to act using the
existing criteria recommendations based on the methodology by which
they are derived, and put standards into place to assist the
implementation of control programs to protect the health of the public
and the environment.
In this instance, EPA has completed a cancer reassessment for PCBs
and has subjected that analysis to extensive scientific analysis and
debate, including an external peer review. EPA believes this
reassessment provides a strong scientific basis for revision of the
PCBs human health criteria. Commenters have not provided EPA with
epidemiological data or other information sufficiently compelling for
EPA to delay amending the NTR to incorporate the revised criteria.
Accordingly, it is EPA's view that the promulgation process should go
forward.
2. Two commenters did not agree that the proposed rule results in
ambient water quality criteria for human health that are less stringent
than those currently in the NTR.
Response: The Agency does not believe that the new criteria based
on total PCBs are more stringent. As discussed above, and in the 1998
proposed rule, the new human health criteria specify concentration
limits of 0.00017 μg/L for total PCBs, in contrast to the old
criterion of 0.000044 μg/L for each of seven different
Aroclors. The old criteria would, in theory, have allowed 0.000308
μg/L total PCBs if each of the seven Aroclors were at its
limit. EPA does not believe this is a reasonable assumption. The new
criterion is not more stringent than the old because several of the
Aroclors are not prevalent in commerce or in the environment. Aroclor
1242 alone accounted for 52 percent of U.S. PCB production, and
Aroclors 1016, 1242, 1254, and 1260 together accounted for over 90
percent. Thus, it is highly unlikely that all seven Aroclors would be
present in similar concentrations. Further, from what we know about how
PCBs degrade and partition into different environmental media and
bioaccumulate in living organisms, environmental PCBs do not look like
the seven industrial Aroclors at their limits. For example, PCBs in
fish or sediment would contain PCB congeners of high chlorine content
and be characterized as ``like'' Aroclor 1254 or 1260. PCBs in water
would contain PCB congeners of lower chlorine content and be
characterized as ``like'' one or two Aroclors of lower chlorine
content. This conclusion is confirmed when environmental samples are
characterized in terms of Aroclor mixtures; experience shows that no
more than two or three Aroclors are used. Accordingly, it is unlikely
that an environmental sample could be characterized in terms of similar
concentrations of the seven different Aroclors.
3. Several commenters prefer criteria for individual Aroclors stating
that the proposed criteria based on total PCBs were inappropriate.
Their objections include:
(a) Only one slope factor and one BCF were used to derive the
criteria rather than different slope factors and BCFs for each
individual Aroclor;
(b) Environmental samples are likely to contain the four most
common Aroclors and the proposed criterion is equal to the sum of these
four most common Aroclors;
(c) Criteria based on total Aroclors are inaccurate because
formulations in different lots can differ by 2-5 fold for many PCB
congeners, making even Aroclor estimated PCB levels inconsistent with
each other if different lots of a formulation are used in different
labs;
(d) Differences between environmental samples and commercial
mixtures make accurate summations of Aroclors difficult and therefore
it is unlikely that an accurate estimation can be made of total PCBs
(i.e., total Aroclors);
(e) Criteria based on sum of PCBs are too stringent because
monitoring programs and analytical labs quantify PCBs as multiple
Aroclor formulations, and the sum of PCBs would exceed the proposed
total criteria;
(f) PCB congeners are shared by several Aroclors, thus, measuring
total Aroclors could double or triple count some congeners leading to
inaccurately high total PCB levels;
(g) It is not possible to characterize PCB congeners as ``like''
Aroclors and it is unlikely that an accurate estimate can be made of
total PCBs; and
(h) It is not appropriate to develop a single criterion because the
Agency does not expect to find all seven Aroclors in significant
quantities in samples.
Response: The Agency does not agree that individual criteria for
each Aroclor should be maintained. The revised PCB criteria were
derived using a single cancer potency factor and a single
bioconcentration factor (BCF) because as discussed below, in the
Agency's view, this approach protects against the major exposure
pathway of concern, consumption of contaminated fish and shellfish.
The Agency adopted an approach in its new cancer reassessment,
``PCBs: Cancer Dose-Response Assessment and Application to
Environmental Mixtures'' (EPA, 1996) (EPA 600/P-96/001F), that
distinguishes among PCB mixtures by using information on environmental
processes to provide guidance in choosing appropriate slope factors for
representative classes of environmental mixtures and different exposure
pathways. In this methodology, exposure through the food chain is
associated with higher risks than other exposures. Preferential
bioaccumulation through the food chain tends to concentrate certain
highly chlorinated congeners which are often among the most toxic and
persistent. Thus, EPA chose a cancer potency factor of 2 per mg/kg-d,
the upper bound slope factor, to calculate the revised human health
criteria. Humans can be exposed to PCBs through the food chain which is
an exposure pathway where environmental processes are likely to
increase risk.
EPA uses a single bioconcentration factor (BCF), from the 1980
criteria guidance document, ``Ambient Water Quality Criteria for
Polychlorinated Biphenyls,'' (EPA 440/5-80-068), to derive the criteria
for today's rule. This BCF, 31,200 L/kg, was derived from data from 21
studies of several different Aroclors and two specific congeners and in
the Agency's view represents an average bioaccumulation factor for PCBs
in all freshwater fish and shellfish.
EPA recently proposed revisions to the methodology it uses to
derive water quality criteria for human health (63 FR 43755, August 14,
1998). In the revised human health methodology, EPA expects to
recommend the use of bioaccumulation factors (BAFs) in place of BCFs.
However, until the proposed changes to the human health methodology are
finalized, EPA will continue to rely on existing criteria or components
(e.g., BCFs or q1*s) of existing criteria as the basis for regulatory
and non-regulatory decisions. Until EPA revises and reissues the
criteria or component using the revised human health methodology the
existing criteria or components are viewed as scientifically acceptable
by EPA.
[[Page 61186]]
The fact that the Agency changed its approach from one where each
Aroclor had its own criterion to one where a single criterion applies
to total PCBs does not stem from the fact that not all Aroclors are
likely to be present in the environment at significant concentrations
as a commenter would suggest. As mentioned above, the Agency changed
its approach for regulating PCBs because PCBs degrade, partition,
transform and selectively bioaccumulate in living organisms. The Agency
agrees it is unlikely that an environmental sample characterized in
terms of Aroclors would resemble an original Aroclor mixture in any
definable way. This is why the Agency stated that if an environmental
sample was characterized in terms of Arolors it could only be
characterized as ``like'' a particular Aroclor. It is difficult to
characterize environmental samples in terms of Aroclors.
The Agency agrees that characterizing environmental samples in
terms of Aroclors can result in under or overestimating PCBs. In
measuring PCB concentrations in terms of Aroclors, certain ratios of
characteristic congeners are considered representative of a particular
Aroclor. When these characteristic congeners are detected in
appropriate ratios, they are quantified as a certain Aroclor. Because
some congeners are present in more than one Aroclor, there is a
possibility of double (or triple) counting a particular congener in
quantifying an Aroclor. There are techniques available to minimize
double counting though, such as use of two different gas chromatograph
(GC) columns or adjusting instrument conditions to get sufficient
separation of peaks. These techniques allow an analyst to view samples
on different chromatographs at slightly different retention times in
order to minimize interference from overlapping peaks. Analysts also
exercise ``Best Professional Judgment'' in selecting the appropriate
peaks for use in quantifying samples in order to minimize
quantification errors.
The possibility of underestimating total PCB concentrations using
Aroclor analyses also exists. In cases where congeners are detected in
environmentally altered mixtures but not in characteristic ratios, the
congeners detected may not be quantified because they do not resemble a
particular Aroclor. In this case Aroclor measurements would
underestimate concentrations of total PCBs present.
EPA agrees that Aroclor formulations may vary substantially by lot
(e.g., percent of a particular congener present). Measuring congener
concentrations rather than Aroclor concentrations eliminates problems
associated with congener weight percent variations between different
lots of a particular Aroclor formulation. Congener analyses are not
impacted by variations between formulations. Aroclor analyses can be
influenced by lot-to-lot variations due to the difference in using
specific congeners as calibration standards versus using Aroclors for
calibration standards.
4. One commenter states that EPA bases the new PCB criteria on only one
or a couple of unspecified, highly chlorinated Aroclors, and not all
Aroclors. The commenter believes that EPA should apply the criteria to
individual Aroclors or the combination most like that which is found in
the samples.
Response: The Agency does not agree that the new PCB criteria are
based on only one or a couple of unspecified, highly chlorinated
Aroclors. The risk-assessment used as the basis for this rulemaking,
``PCBs: Cancer Dose-Response Assessment and Application to
Environmental Mixtures,'' is based on a range of potency estimates,
developed using studies for a range of mixtures (commercial mixtures
only), instead of focusing only on the highest-potency mixture. Section
2 of the risk assessment provides brief summaries on the studies used
in developing the dose-response assessment.
Again, as discussed above in Response #3, it is the Agency's view
that human health water quality criteria for PCBs should be expressed
in terms of total PCBs rather than on individual Aroclors.
5. One commenter disagrees with EPA's statement that, ``Some PCBs
congeners can accumulate selectively in living organisms'' (63 FR
16184.) The commenter considers this statement an unfair generalization
and asks EPA to identify the specific congeners that selectively
accumulate in various classes of living organisms and those that do
not.
Response: Accumulation patterns can vary by species and location.
One compilation of bioaccumulation information cited in the
reassessment was done by McFarland and Clarke (1989). EPA's
reassessment also cites other studies that show retention and
bioaccumulation of specific congeners.
6. The commenter asks EPA to clarify its use of the term ``toxic'' in
the statement, ``It is noteworthy that bioaccumulated PCBs appear to be
more toxic than commercial PCBs . . .'' (63 FR 16184). If the reference
is to carcinogenicity, the commenter states that this statement is
speculation and has not been scientifically demonstrated in human or
animal studies.
Response: Recent animal studies (Mayes, 1998) with commercial
mixtures have demonstrated that every PCB mixture tested poses a risk
of cancer. The commercial mixtures tested by Brunner et al., (1996,
later published by Mayes (1998)), Aroclor 1016, 1242, 1254 and 1260,
together accounted for over 90 percent of the U.S. PCB production.
These four commercial mixtures contain overlapping groups of congeners
that, together span the range of congeners most often found in
environmental mixtures (Cogliano, 1998). Commercial mixtures of PCBs
can cause cancer and environmental mixtures contain subsets of
congeners from commercial mixtures.
Preferential bioaccumulation of PCBs can occur in humans, fish and
wildlife. PCBs are highly soluble in lipids and are absorbed by
organisms. Different species in the food chain retain persistent
congeners that prove resistant to metabolism and elimination (Oliver
and Niimi, 1988). While persistence is not synonymous with toxicity, in
the absence of testing on most congeners, it is reasonable to suppose
some correlation between persistence and toxicity (EPA, 1996), because
persistence of PCBs in the body can enhance the opportunity for
congeners to express tumor promoting activity (Safe, 1994).
7. A commenter disagrees with Dr. Wiltse's (EPA) statement that
``cancer risk assessment for PCBs is beyond the scope of this
rulemaking.''
Response: The actual statement Dr. Wiltse made in replying to a
request for an extension to the comment period for this rulemaking (see
comment #1 above), based on the expectation of the future availability
of an analysis of epidemiological data was:
Revisions to the cancer risk assessment used as the basis for
this proposed rule (``PCBs: Cancer Dose-Response Assessment and
Application to Environmental Mixtures,'' September 1996) may be
considered in the future based on the epidemiological data provided
by The General Electric Company or other new data on PCBs. However,
revising the entire cancer risk assessment for PCBs is beyond the
scope of this rulemaking action and is not feasible prior to
[[Page 61187]]
promulgation of this specific action on the NTR.
As noted in its response to comment #1 above, the Agency recently
completed a major reassessment of all the available data for PCBs (EPA
1996) which was satisfactory to independent peer reviewers. The Agency
believes this reassessment provides a strong scientific basis for
revising the human health criteria for PCBs. In this rulemaking, EPA is
amending the NTR to include the revised criteria as provided in the
Settlement Agreement discussed above. A commenter has suggested that
EPA should defer this promulgation pending analyses of new scientific
information concerning risk to human health from occupational exposure
to PCBs. The commenter informed the Agency that they are in the process
of analyzing epidemiological data for capacitor workers exposed to PCBs
and expected to have that analyses available in the near term.
EPA believes its cancer risk assessment provides a strong
scientific basis for the revised PCB human health criteria. The Agency
must make decisions based on the available, scientifically defensible,
data. EPA does not agree that revisions of the PCB criteria should be
delayed based upon the expectations of future analyses of
epidemiological data.
Scientific information is constantly evolving and there can be a
long lag time from conducting research and analyzing data, to preparing
risk assessments and obtaining peer review, and developing human health
criteria. When the commenter's analysis has been made available to the
Agency, EPA will of course consider this information and any other new
information. Indeed, EPA anticipates that its next assessment of PCB
risks will again examine closely whether the current criteria are
sufficiently protective of children given continuing research by the
Agency for Toxic Substance and Disease Registry.
8. Several comments were received regarding the use of epidemiological
data to generate a cancer potency factor for PCBs. The comments include
the following:
(a) Cancer slope factors from epidemiological studies can be used
to establish environmental standards. A cancer slope factor is
calculated using the negative results of Taylor (1988), the positive
results of Brown (1987), the measured cancer incidence rate, and the
95% upper confidence limit on the incremental risk rate. This results
in cancer slope factors ranging from 7.7E-4 (measure, Taylor) to 1.9E-2
(95% UCL, Brown). The cancer slope factor for the Taylor study (7.7E-4)
is conservatively assumed to equal the cancer slope factor for Aroclor
1242 (workers were exposed to Aroclor 1242, 1254 and 1016). Using an
animal study of cancer risk (Mayes 1998) which concluded that Aroclor
1260 is 5 times as potent as 1242, the suggested environmental standard
would be 3.8E-3 per mg/kg/day (5 * 7.7E-4). This standard is 519 times
greater than the proposed value.
(b) Any cancer slope factor calculated from epidemiological studies
which reported air concentrations would overestimate cancer risk of
PCBs. Air concentrations would significantly underestimate exposure
since dermal exposure and incidental ingestion also form significant
exposure routes. Dermal exposure studies, despite uncertainty in
quantifying dermal absorption of PCBs, can be used to estimate PCB
exposure if conservative assumptions are used as in the Terra (1993)
analysis.
(c) EPA has not thoroughly reviewed the epidemiological studies
performed to date or considered how they can be used in risk
assessment. Specifically, EPA should consider the numerous
epidemiological studies performed on populations with extensive
workplace exposure to PCBs which do not support the proposition that
PCBs cause cancer in humans or lead to increased mortality from cancer.
Also, given the uncertainty in cancer dose response modeling, the
Agency should reexamine the evidence for carcinogenic risk that can be
derived from human epidemiological studies.
(d) It has been stated that epidemiological studies are not as
statistically robust as animal studies, however, the commenter states,
in many cases human epidemiological data should be used to validate,
confirm, or set upper bound estimates of carcinogenic potency. In
general when epidemiological data are available, it is not appropriate
to accept only the result of mathematical models that analyze rodent
data without serious consideration to the human experience (Cook, 1982;
Dinman and Sussman, 1983; Layard and Silvers, 1989). Animal studies
(rat feeding studies) may indicate cancer in rats, but there may not be
a direct transfer of cancer incidence in humans, particularly at
environmental or occupational exposure levels. Many instances exist of
chemicals that are potent rodent carcinogens but do not pose an
equivalent cancer hazard in humans.
Response: The commenters' arguments and studies they cite were
available at the time EPA drafted its reassessment. EPA as well as the
external panel that reviewed EPA's reassessment concluded that
epidemiological data are inadequate for use in a quantitative risk
assessment. The external panel strongly recommended that EPA base its
reassessment on the Brunner et. al., (1996) study, that was later
published by Mayes (1998). EPA's quantitative assessment reflects the
advice of the external panel in this regard. (See: ``Report on Peer
Review Workshop on PCBs: Cancer-Dose Response Assessment and
Application to Environmental Mixtures,'' May 1996.)
9. The commenter suggests that EPA use state-of-the-art methodology for
interpreting the results of epidemiological studies, particularly a
weight-of-the-evidence test and ``causation analysis.'' Additionally,
the commenter notes that studies which have larger cohorts and numbers
of cancer deaths are inherently more important than are studies with
smaller cohorts and fewer deaths when applying the weight-of-the-
evidence test.
Response: The Agency uses the weight-of-evidence approach for
interpreting the results of the epidemiological studies. The
epidemiological studies have been found to provide limited (IARC, 1987)
to inadequate (EPA, 1988) evidence of carcinogenicity. The overall
conclusion, however, uses the weight-of-evidence approach on the entire
data base, human and animal. Recent animal tests, Mayes (1998), have
demonstrated that every PCB mixture tested poses a risk of cancer.
The Agency does note that cohort size is one of the many factors
that goes into a weight-of-evidence analysis. Weight-of-evidence
analyses also include exposure factors such as exposure level, exposure
duration and lack of confounding exposure.
10. The commenter notes that it is unclear how the inclusion of
noncarcinogenic Aroclors (1016 and 1254) in the total PCB criteria
affects compliance determinations as human health criteria are based on
cancer potential. The commenter suggests that their inclusion would
over-estimate the risk to human health. This issue supports the
argument for the development of individual criteria for individual
Aroclors rather than for total PCBs.
Response: The Agency does not agree with the commenter that
Aroclors 1016 and 1254 are non-carcinogenic. The 1996 cancer dose-
response assessment for PCBs includes new data from Brunner et al.,
(1996) in which rats fed
[[Page 61188]]
diets containing Aroclors 1260, 1254, 1242 or 1016 were found to have
statistically significant, dose-related, increased incidences of liver
tumors from each mixture. The Mayes (1998) data indicate that Aroclor
1254 was the most potent of the four mixtures tested.
As previously discussed, the 1996 cancer dose-response assessment
does acknowledge that overall, human studies are considered to provide
limited (IARC, 1987) to inadequate (EPA, 1988) evidence of
carcinogenicity. This notwithstanding, animal studies are considered to
provide sufficient evidence of carcinogenicity and thus some commercial
PCB mixtures have been characterized as probably carcinogenic to humans
based on these findings (IARC, 1987; EPA, 1988) (EPA, 1996). The Agency
does not agree that inclusion of Aroclors 1016 and 1256 in the total
PCB determinations over-estimates the risk posed to humans.
Although there is sufficient evidence of carcinogenicity for
Aroclor 1016 and 1254, Aroclor 1016 was found to have a several-fold
lower potency compared to Aroclor 1242 (Brunner et al., 1996). The
approach adopted in the 1996 cancer reassessment for PCBs does account
for differences in potency by establishing a range of dose-response
slopes. Information on environmental processes is then used to provide
guidance on choosing the appropriate slope factor to apply. Likewise,
the Agency recognizes that not all environmental mixtures are regarded
as equally potent; environmental mixtures differ from commercial
mixtures and from each other (EPA, 1996).
11. EPA acknowledges that the mode of action of PCBs is promotional.
Therefore, PCBs should be considered as epigenetic carcinogens and
assessed with a margin of exposure approach rather than by the linear
95th%ile carcinogenicity modeling appropriate for genetic toxins.
Response: Although genetic activity testing for PCBs is generally
negative, the mode of action of PCBs has not been established. In such
a case, it is appropriate to use a linear extrapolation under EPA's
existing 1986 cancer guidelines. This would also be the case under the
Agency's 1996 proposed cancer guidelines. Moreover, at low doses, some
PCB congeners add to the considerable background of human exposure to
dioxin-like compounds and augment processes associated with dioxin
toxicity, providing an expected linear component to the dose-response
curve. There is also considerable background exposure to nondioxin-like
congeners, so additional PCB exposure can augment other carcinogenic
processes that may be operating.
12. The commenter believes that the linear method for estimating the
carcinogenic potency of PCBs is likely to overestimate the low-dose
carcinogenic risk of PCBs. The commenter refers to a study by Ottobonni
(1984) which suggests that genotoxic agents may exhibit thresholds at
low doses, thus there is considerable uncertainty in the assumption of
low dose linearity for carcinogens. EPA's proposed cancer guidelines
(EPA, 1996) allow for non linear low dose extrapolation in cases where
the available data support a nonlinear mode of action.
Response: Linear low-dose extrapolation does, indeed, yield an
upper bound on the potential risk, albeit a plausible upper bound. As
discussed in the response to comment #11, there is not sufficient
information available at this time to support a non linear
extrapolation under the existing 1986 cancer guidelines, nor would
there be under the 1996 proposed cancer guidelines.
13. The mode of action data for PCBs as tumor promoters and not
initiators was not given appropriate considerations, thus EPA's
reassessment completed in September 1996 was not consistent with the
proposed cancer risk assessment guidelines. EPA should delete its
statements claiming that the 1996 reassessment was consistent with
proposed EPA cancer risk assessment guidelines.
Response: As discussed in the responses to comment #11 above, EPA
did consider the mode-of-action data, concluding that there was not
sufficient information available at this time to support non linear
extrapolation. Moreover, several features of the 1996 reassessment were
clearly motivated by the 1996 proposed cancer guidelines: developing a
range of potency estimates instead of focusing on the highest-potency
mixture, using the LED10/ED10 approach instead of the linearized
multistage procedure, and using the cross-species scaling factor based
on the \3/4\ power of relative body weight. Most important, however, is
the reassessment's emphasis on discussing circumstances that affect
cancer risks, in this case, how environmental processes alter the
composition and toxicity of PCB mixtures.
14. The commenter notes difficulties in estimating human cancer risks
from rodent bioassays, particularly that tumor promoters often produce
rodent liver tumors in long term bioassays, but are not generally known
to cause cancer in humans. Tumor promoters like PCBs selectively
increase the growth of cancerous cells but do not interact to cause the
initial heritable change which begins the multi-stage process of
cancer.
Response: Although noting that there are uncertainties in
estimating human cancer risks from any animal study, it is not correct
to suggest that EPA is concerned only about substances that cause the
initial heritable genetic change in cancer development. Because cancer
development is a multistage process, any substance that brings about or
accelerates any of these stages can increase the risk of ultimately
developing cancer.
15. EPA's statement that the major pathway of exposure to PCBs is
through food ( 63 FR 16184) is not supported by human epidemiological
studies which show very similar burdens of total PCBs and congener
profiles between consumers and nonconsumers of fish. Other major
sources for PCBs exist and, additionally, fish consumption may not be
the primary route of exposure. EPA's statement should be revised or
deleted.
Response: EPA notes in its cancer risk assessment for PCBs, that
PCBs are widespread in the environment and that humans are exposed to
PCBs through multiple pathways. Nonetheless, recent multimedia studies
indicate that the major exposure pathway to persistent toxic substances
such as PCBs is through food (i.e., contaminated fish and shellfish
consumption). Birmingham et al., (1989), Newhook (1988) and Fitzgerald
et al., (1996) found that fish consumption appears to be the major
pathway of exposure for PCBs. The majority of peer reviewers for the
PCB Cancer Dose-Response Assessment agreed that consumption of
contaminated fish is considered to be the predominant source of PCB
contamination for humans. Exposure to PCBs through fish consumption is
associated with high risk in the revised cancer assessment for PCBs.
[[Page 61189]]
16. EPA's statement (63 FR 16184) that ``all PCBs cause cancer''
implies a fact that has not yet been demonstrated. EPA considered all
cancer studies which used commercial mixtures only. There is still no
strong supporting evidence of carcinogenicity in humans and the PCBs
tested in animals were commercial formulations, but that is not
conclusive evidence that all PCB congeners are cancer-causing. Many PCB
congeners are unlikely to cause cancer. The suggested revision of the
statement would be ``all commercial Aroclor formulations can cause
cancer in animals.''
Response: EPA's new assessment considered all cancer studies (which
used commercial mixtures only) including a new study (Brunner, 1996) of
four Aroclor's that strengthen the case that all PCBs cause cancer. The
four mixtures used in the Brunner study contain overlapping groups of
congeners that, together, span the range of congeners most often found
in environmental mixtures (Cogliano, 1998). EPA used this information
to develop a range of dose response slopes, changing from a single
dose-response cancer potency factor to a range of slope factors. Even
though the Agency developed a range of slope factors in its
reassessment, a single slope factor is selected from the range, based
on the likely exposure pathway, to develop a criterion.
Although animal feeding studies demonstrate the carcinogenicity of
commercial PCB preparations, as discussed previously, it is not known
which of the PCB congeners in such preparations are responsible for
these effects, or if decomposition products, contaminants or
metabolites are involved in the toxic response. In the absence of
information ruling out the possibility that certain PCB isomers are not
carcinogenic EPA believes it is a prudent public health policy to be
conservative and regulate as if all PCBs are carcinogenic.
17. The use of a risk factor of 10-6 may be overly
stringent. Virginia has sufficiently protective human health standards
that use a risk factor of EPA 10-5.
Response: EPA recognizes the primary authority of States to adopt
water quality standards; and Agency policy generally allows States to
select an appropriate risk level within the general range of
10-4 to 10-6. EPA uses a 10-6 risk
level in setting its human health water quality criteria. In order for
the human health criteria to be implemented in water quality programs,
a single risk level must be chosen so that a specific numeric limit is
established for a pollutant. Some States use a different risk factor,
and in the NTR, EPA applied the State's risk factor in calculating the
criteria promulgated for that State.
Any State adopting its own standards that meet the requirements of
the Act may adopt a risk level other than that used by EPA. The ability
of a State to select an alternative risk level is one of the reasons
EPA encourages each State to adopt its own water quality standards
rather than rely on Federal promulgations.
18. EPA is using a database dated 1980 or earlier for items such as
bioconcentration factor and fish consumption rate. As the revised
criteria will serve as the basis for regulatory actions, the criteria
should reflect the current state-of-the-science.
Response: In this rulemaking, EPA did rely on existing
bioconcentration and fish consumption data. Until proposed revisions to
the methodology the Agency used to derive human health criteria is
finalized, the Agency will continue to rely on the existing criteria or
components which are still scientifically defensible. As discussed in
#1, scientific information is always evolving and EPA believes it is
not in the public interest to defer action on criteria awaiting new
methodology or data.
19. The proposed water quality standards for human health protection
are in the part per quadrillion range and proposed aquatic standards
are 14 part per trillion (ppt), but the lowest detectable concentration
which the ``best'' technique has been able to measure is 40 ppt. EPA
must refrain from establishing restrictive limits without providing the
analytical methodology capable of achieving these levels.
Response: EPA's water quality standards regulation at 40 CFR 131.11
requires that criteria be adopted by States at concentrations necessary
to protect designated uses. EPA has determined that consideration of
analytical detect ability would not be an appropriate factor to
consider when calculating the water quality criteria component of water
quality standards. EPA's human health criteria are developed from
protocols generally using toxicity studies on laboratory animals such
as mice and rats. Thus, EPA criteria are effect-based without regard to
chemical analytical methods or techniques. This has been the Agency's
position since the inception of the water quality standards' program in
1965.
Because water quality standards developed pursuant to section
303(c) of the Clean Water Act are not self-enforcing, the measurement
of these chemicals in a regulatory sense is generally in the context of
an NPDES permit limitation. Although the sensitivity of analytical
methods is not an appropriate basis for setting water quality criteria
or water quality-based effluent limitations, analytical methods are
needed for monitoring and assessing compliance with water quality-based
permit limits. The permit issuing authority, either a State or EPA,
establishes the analytical methodology to be used in assessing
compliance with the permit limit.
20. Fin fish must be exposed to PCBs in the water column for extended
periods of time to attain the levels of bioconcentration represented by
the BCFs used to calculate human health criteria. Exceedance of
criteria values in the water column will only result in human health
impact if the tissue of the fish being consumed has reached equilibrium
with the water column PCBs. Species traveling in and out of waters
believed to exceed the criteria may actually contain little or no PCBs.
Response: EPA agrees that for certain highly hydrophobic congeners
of PCBs, extended exposure periods are required to achieve steady-state
between fish and the water column. However, the Agency does not agree
that human health impacts can only occur in cases where the criteria
were exceeded and fish tissue reached equilibrium with the water
column. Specifically, bioaccumulation of a chemical to harmful levels
in aquatic organisms can occur even if steady-state conditions have not
been reached. For high log KOW compounds such as certain PCB
congeners, chemical concentrations in fish and other higher trophic
level aquatic organisms are a function of the long-term average
concentration in their environment (water exposure in the case of
bioconcentration factor-based criteria). Therefore, achieving
unacceptable tissue concentrations can result under non-steady
conditions if the long-term average exceeds the human health criterion,
which would occur if the exposures above the criterion level are not
completely offset by exposures below the criterion.
In cases where chemicals and organisms require relatively long time
periods to reach steady-state (such as for certain highly hydrophobic
PCB congeners), the Agency would agree that migrating organisms may not
be
[[Page 61190]]
exposed to pollutant concentrations in the water column for sufficient
periods of time for tissues to reach equilibrium conditions. Under some
circumstances, migration of fish in and out of marginally contaminated
areas (i.e., defined as those areas with water concentrations at or
slightly above criteria levels) may result in tissue levels of certain
highly hydrophobic PCB congeners that are below levels represented by
the BCF in the human health criterion. However, this circumstance may
not hold true for all organisms, PCB congeners, and exposure conditions
that can exist in the United States. Moreover, in cases where organisms
accumulate highly hydrophobic compounds (i.e., high log KOW
compounds), pollutants may be retained after organisms leave an
exposure area due to slow depuration. In this case, an organism could
travel out of an exposure area, but retain a contaminant in its tissue.
Specifically, EPA's ambient human health water quality criteria are
national in scope, they are designed to be protective of the vast
majority of exposure conditions that can occur in U.S. waters. These
conditions include exposure via consumption of aquatic organisms that
are sedentary and do not migrate (e.g., clams, oysters, mussels) in
addition to consumption of other shellfish and finfish which may reside
for long periods of time at a specific site (e.g., bottom dwelling
finfish such as flounder and catfish). Furthermore, EPA's national
criteria must be protective of both open (e.g., riverine) and closed
(e.g., reservoirs, lakes) aquatic ecosystems. In relatively closed
systems such as lakes and reservoirs, migration of fish from a
contaminant-influenced site may be restricted such that even highly
mobile organisms can achieve unacceptable tissue burdens of PCBs as a
result of marginal exceedences of EPA's PCB criteria. Finally, EPA
notes that its PCB criteria apply to total PCBs which represents a
mixture of PCB congeners with KOWs that vary up to three
orders of magnitude. Thus, some moderately hydrophobic PCB congeners
can reach steady state in substantially shorter exposure periods than
other highly hydrophobic congeners. Thus, the commenters' assumption
that long time periods are required to reach steady state does not
apply to all PCB congeners to which EPA's PCB criteria apply.
Therefore, EPA believes that its national ambient water quality
criteria for PCBs are set at an appropriate level of protection
considering the variety of exposure conditions which may arise in U.S.
waters.
21. Criteria expressed solely as fish tissue concentrations only
examine the after-effects of pollution rather than ensure that
designated uses are adequately protected from pollution.
Response: When proposed revisions to the human health methodology
(63 FR 43756, August 14, 1998) are finalized, the Agency expects to
allow ambient water quality criteria to be expressed in terms of fish
tissue concentrations as an alternative to water concentrations in some
cases. Particularly for substances that are expected to exhibit
substantial bioaccumulation, the water quality criteria may be a very
low value. Consequently, it may be more practical and meaningful in
these cases to focus on the concentration of those substances in fish
tissue, since fish ingestion would be the predominant source of
exposure for substances that bioaccumulate. Even so, these fish tissue
criteria would still correspond to an ambient water quality criteria
(AWQC), expressed as a water concentration, calculated by multiplying
the AWQC (water concentration) by the bioaccumulation factor (BAF) used
to develop the AWQC. Whether concentration limits are based on a fish
tissue concentration or water column concentrations will therefore make
little or no difference. It could be argued that either a fish tissue
concentration or water column concentration is derived to be
protective, or only examines the after-effects of pollution. Both water
column concentrations and fish tissue concentrations are intended to
prevent harmful accumulations from occurring.
EPA may allow ambient water quality criteria for certain compounds
to be expressed in terms of fish tissue concentrations when the
proposed human health methodology is finalized. However, no final
decisions will be made by the Agency regarding the expression of
criteria in terms of fish tissue concentrations until the proposed
revisions to the human health methodology are finalized.
22. The commenter suggests the use of fish tissue concentrations
together with ambient criteria. While it is true that some criteria are
below levels which can be reliably measured, such criteria serve a
valuable purpose to prevent build-up of pollutants in fish tissues.
Response: As stated above, the Agency expects to allow ambient
water quality criteria for protection of human health to be expressed
in terms of fish tissue concentrations as an alternative to water
concentrations when it finalizes the proposed human health methodology
revisions. Expressing criteria in terms of fish tissue concentrations
would allow for measurements of pollutants that would otherwise be
difficult. The Agency's approach does not include both a water
concentration and a fish tissue concentration, but rather, relates the
water concentration to an appropriate fish tissue concentration as
outlined in the proposed revisions to the human health methodology (63
FR 43756, August 14, 1998).
Again, as mentioned above, EPA may allow ambient water quality
criteria for certain compounds to be expressed in terms of fish tissue
concentrations when the proposed human health methodology is finalized.
However, no final decisions will be made by the Agency regarding the
expression of criteria in terms of fish tissue concentrations until the
proposed revisions to the human health methodology are finalized.
G. References
ATSDR. 1993. ``Toxicological Profile for Polychlorinated
Biphenyls''. U.S. Department of Health and Human Services, Public
Health Service, Agency for Toxic Substances and Disease Registry
(ATSDR), Atlanta, GA, Report No. ATSDR/TP-92/16.
ATSDR. 1995. ``Toxicological Profile for Polychlorinated
Biphenyls''. U.S. Department of Health and Human Services, Public
Health Service, Agency for Toxic Substances and Disease Registry
(ATSDR), Atlanta, GA, Report for public comment.
Birmingham B., Gilman, A., Grant, D., et al. ``PCDD/PCDF multimedia
exposure analysis for the Canadian population: detailed exposure
estimation. Chemosphere, v. 19, (1989), pp. 637-642.
Brunner, M.J., T.M., Singer, A.W., Ryan, M.J., Toft, ll, J.D.,
Menton, R.S., Graves, S.W., and A.C. Peters, (1996). ``An assessment
of the chronic toxicity and oncogenicity of Aroclor-1016, Aroclor-
1242, Aroclor-1254, and Aroclor-1260 administered in diet to rats''.
Columbus, OH: Battelle Study No. SC920192, Chronic toxicity and
oncogenicity report.
Cogliano, V.J. ``Assessing the cancer risk from environmental
PCBs''. Environ. Health Perspect. v. 106, 6, (1998), pp. 317-323.
Fitzgerald, E.F., K.A. Brix, D.A. Deres, et al. ``Polychlorinated
biphenyl (PCB) and dichlorodiphenyl dichloroethylene (DDE) exposure
among Native American men from contaminated Great Lakes fish and
wildlife''. Toxicol Ind. Health, v. 12, (1996), pp. 361-368.
[[Page 61191]]
IARC. 1987. ``IARC Monographs on the Evaluation of Carcinogenic
Risks to Humans,'' Supplement 7, Overall Evaluations of
Carcinogenicity: An Updating of IARC Monographs Volumes 1-42.
International Agency for Research on Cancer, Lyon, France, (1987).
Johnson, B.L., H.E. Hicks, W. Cibulas, O. Faroon, A.E. Ashizawa, C.
T. De Rosa, V.J. Cogliano and M. Clark. ``Public Health Implications
of Exposure to Polychlorinated Biphenyls (PCBs).'' U.S. Public
Health Service, The Agency for Toxic Substances and Disease
Registry, U.S. Department of Health and Human Services and The U.S.
Environmental Protection Agency.
Mayes, B.A., E.E. McConnell, B.H. Neal, M.J. Brunner, S.B. Hamilton,
T.M. Sullivan, A.C. Peters, M.J. Ryan, J.D. Toft, A.W. Singer, J.F.
Brown, Jr., R.G. Menton, and J.A. Moore. ``Comparative
carcinogenicity on Sprague-Dawley rats of the polychlorinated
biphenyl mixtures Aroclors 1016, 1242, 1254, and 1260.'' Toxicol.
Sci. v. 40, (1998), pp. 62-76.
MacFarland, V.A. and J.U. Clarke. ``Environmental occurrence,
abundance, and potential toxicity of polychlorinated biphenyl
congeners considerations for congener-specific analysis.'' Environ.
Health Perspect. v. 81, (1989), pp. 225-239.
Newhook, R.C. ``Polychlorinated biphenyls: multimedia exposure
analysis''. Contract report to the Department of National Health and
Welfare, Ottawa, Canada. (1988).
Norback, D.H. and R.H. Weltman. ``Polychlorinated biphenyl induction
of hepatocellular carcinoma in the Sprague-Dawley rat''. Environ.
Health Perspect. v. 60, (1985), pp. 97-105.
Oliver, B.G. and A.J. Niimi. ``Trophodynamic analysis of
polychlorinated biphenyl congeners and other chlorinated
hydrocarbons in the Lake Ontario ecosystem. Envion. Sci. Technol. v.
22, (1988), pp. 388-397.
Safe, S. Polychlorinated biphenyl (PCBs): environmental impact,
biochemical and toxic responses, and implications for risk
assessment. Crit. Rev. Toxicol. 24(2):87-149. (1994)
TERRA, Inc. James, R.C., J.D. Schell and R.W. Freeman. ``Comments on
Water Quality Guidance for the Great Lakes System''. Report prepared
for: Polychlorinated Biphenyl Panel of the Chemical Manufacturers
Association, Utility Solid Waste Activities Group of Edison Electric
Institute, and National Electrical Manufacturers Association.
(1993).
USEPA, ORD. ``PCBs: Cancer Dose-Response Assessment and Application
to Environmental Mixtures.'' Prepared by the National Center for
Environmental Assessment, Washington, DC, (September 1996): EPA/600/
P-96/001F.
USEPA, OW. ``Ambient Water Quality Criteria for Polychlorinated
Biphenyls''. Prepared by the Office of Water, Regulation and
Standards, Criteria and Standards Division, Washington, DC, (October
1980): EPA/400/5-80-068.
USEPA. ``Drinking Water Criteria Document for Polychlorinated
Biphenyls (PCBs)''. Prepared by ECAO, Cincinnati, Ohio, (1988):
ECAO-CIN-414.
USEPA, OW. ``Draft Water Quality Criteria Methodology: Human
Health''. Prepared by the Office of Water, Washington, DC, (August
1998): EPA/822-Z-98-001.
USEPA. (1995). USEPA 635500, Final Water Quality Guidance for Great
Lakes System; Response to Comment Document.
USEPA. (1986). Guidelines for carcinogen risk assessment. FR
51(185):34014-34025.
USEPA. (1996a). Proposed guidelines for carcinogen risk assessment;
notice, FR 61(79):17960-18011.
H. Regulatory Assessment Requirements
1. Executive Order (E.O.) 12866, Regulatory Planning and Review
Under Executive Order 12866, (58 Federal Register 51,735 (October
4, 1993)) the Agency must determine whether the regulatory action is
``significant'' and therefore subject to Office of Management and
Budget (OMB) review and the requirements of the Executive Order. The
Order defines ``significant regulatory action'' as one that is likely
to result in a rule that may:
(1) Have an annual effect on the economy of $100 million or more or
adversely affect in a material way the economy, a sector of the
economy, productivity, competition, jobs, the environment, public
health or safety, or State, local, or tribal governments or
communities;
(2) Create a serious inconsistency or otherwise interfere with an
action taken or planned by another agency;
(3) Materially alter the budgetary impact of entitlements, grants,
user fees, or loan programs or the rights and obligations of recipients
thereof; or
(4) Raise novel legal or policy issues arising out of legal
mandates, the President's priorities, or the principles set forth in
the Executive Order.
Pursuant to the terms of Executive Order 12866, it has been
determined that this rule is a ``significant regulatory action'' within
the meaning of the Executive Order. As such this action was submitted
to OMB for review. No changes were made as a result of OMB review.
2. The Unfunded Mandates Reform Act
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Pub.
L. 104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on State, local, and Tribal
governments and the private sector. Under section 202 of the UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for proposed and final rules with ``Federal mandates'' that
may result in expenditures to State, local, and Tribal governments, in
the aggregate, or to the private sector, of $100 million or more in any
one year. Before promulgating an EPA Rule for which a written statement
is needed, section 205 of the UMRA generally requires EPA to identify
and consider a reasonable number of regulatory alternatives and adopt
the least costly, most cost-effective or least burdensome alternative
that achieves the objectives of the rule. The provisions of section 205
do not apply when they are inconsistent with applicable law. Moreover,
section 205 allows EPA to adopt an alternative other than the least
costly, most cost-effective or least burdensome alternative if the
Administrator publishes with the final rule an explanation why that
alternative was not adopted. Before EPA establishes any regulatory
requirements that may significantly or uniquely affect small
governments, including Tribal governments, it must have developed under
section 203 of the UMRA a small government agency plan. The plan must
provide for notifying potentially affected small governments, enabling
officials of affected small governments to have meaningful and timely
input in the development of EPA regulatory proposals with significant
Federal intergovernmental mandates, and informing, educating, and
advising small governments on compliance with the regulatory
requirements.
Today's rule contains no federal mandates (under the regulatory
provisions of Title II of the UMRA) for State, local or Tribal
governments or the private sector. The rule imposes no enforceable duty
on any State, local or Tribal governments or the private sector;
rather, this rule establishes ambient water quality criteria which,
when combined with State-adopted designated uses, will create water
quality standards for those water bodies with such adopted uses. The
State may use the resulting water quality standards in implementing
their water quality control programs and in issuing National Pollutant
Discharge Elimination System Permits. Thus, today's rule is not subject
to the requirements of sections 202 and 205 of the UMRA.
EPA has determined that this rule contains no regulatory
requirements that might significantly or uniquely affect small
governments. As stated above, the rule imposes no enforceable
requirements on any party, including small governments. Moreover, any
water
[[Page 61192]]
quality standards, including those promulgated here, apply broadly to
those dischargers and are not uniquely applicable to small governments.
Thus, this rule is not subject to the requirements of section 203 of
UMRA.
3. Executive Orders on Federalism
Under Executive Order 12875, EPA may not issue a regulation that is
not required by statute and that creates a mandate upon a State, local
or Tribal government unless the Federal Government provides the funds
necessary to pay the direct compliance costs incurred by those
governments, or EPA consults with those governments. If EPA complies by
consulting, Executive Order 12875 requires EPA to provide to the Office
of Management and Budget a description of the extent of EPA's prior
consultation with representatives of affected State, local and tribal
governments, the nature of their concerns, any written communications
from the governments, and a statement supporting the need to issue the
regulation. In addition, Executive Order 12875 requires EPA to develop
an effective process permitting elected officials and other
representatives of State, local and Tribal governments ``to provide
meaningful and timely input in the development of regulatory proposals
containing significant unfunded mandates.''
For the same reasons as stated above in section H.2, EPA has
determined this rule does not impose federal mandates on State, local
or Tribal governments. Thus, today's rule is not subject to E.O. 12875.
On August 4, 1999, President Clinton issued a new executive order
on federalism, Executive Order 13132, (64 FR 43255 (August 10, 1999)
which will take effect on November 2, 1999. In the interim, the current
Executive Order 12612 (52 FR 41685 (October 30, 1987) on federalism
still applies. This rule will not have a substantial direct effect on
States, on the relationship between the national government and the
States, or on the distribution of power and responsibilities among the
various levels of government, as specified in Executive Order 12612.
This final rule amends the National Toxic Rule (NTR) to revise the
human health water quality criteria for PCBs. EPA adopted the NTR in
1992 for those States and jurisdictions that had not established
adequate numeric water quality criteria to comply with the Clean Water
Act. States that adopt their own criteria will no longer be subject to
the federal regulation.
4. Executive Order 13084: Consultation and Coordination With Indian
Tribal Governments
Under Executive Order 13084, EPA may not issue a regulation that is
not required by statute, that significantly or uniquely affects the
communities of Indian tribal governments, and that imposes substantial
direct compliance costs on those communities, unless the Federal
government provided the funds necessary to pay the direct compliance
costs incurred by the tribal governments, or EPA consults with those
governments. If EPA complies by consulting, Executive Order 13084
requires EPA to provide to the Office of Management and Budget, in a
separately identified section of the preamble to the rule, a
description of the extent of EPA's prior consultation with
representatives of affected tribal governments, a summary of the nature
of their concerns, and a statement supporting the need to issue the
regulation. In addition, Executive Order 13084 requires EPA to develop
an effective process permitting elected officials and other
representatives of Indian tribal governments ``to provide meaningful
and timely input in the development of regulatory policies on matters
that significantly or uniquely affect their communities.''
Today's rule does not significantly or uniquely affect the
communities of Indian tribal governments nor does it impose substantial
direct compliance costs on them. No Indian tribal governments are
subject to the NTR and therefore are not affected by this rule.
Accordingly, the requirements of section 3(b) of Executive Order 13084
do not apply to this rule.
5. The Regulatory Flexibility Act (RFA) as Amended by the Small
Business Regulatory Enforcement Fairness Act (SBREFA) of 1996
Under the Regulatory Flexibility Act, 5 U.S.C. 601 et seq., as
amended by the Small Business Regulatory Enforcement Fairness Act, EPA
generally is required to conduct a regulatory flexibility analysis
(RFA) describing the impact of the regulatory action on small entities
as part of rulemaking. However, under section 605(b) of the RFA, if the
Administrator certifies that the rule will not have a significant
economic impact on a substantial number of small entities, EPA is not
required to prepare a regulatory flexibility analysis. The
Administrator is today certifying, pursuant to section 605(b) of the
RFA, that this rule will not have a significant economic impact on a
substantial number of small entities. Therefore, the Agency did not
prepare a regulatory flexibility analysis.
The RFA requires analysis of the impacts of a rule on the small
entities subject to the rules' requirements. See United States
Distribution Companies v. FERC, 88 F.3d 1105, 1170 (D.C. Cir. 1996).
Today's rule establishes no requirements applicable to small entities,
and so is not susceptible to regulatory flexibility analysis as
prescribed by the RFA. (``[N]o [regulatory flexibility] analysis is
necessary when an agency determines that the rule will not have a
significant economic impact on a substantial number of small entities
that are subject to the requirements of the rule,'' United Distribution
at 1170, quoting Mid-Tex Elec. Co-op v. FERC, 773 F.2d 327, 342 (D.C.
Cir. 1985) (emphasis added by United Distribution court). ) The Agency
is thus certifying that today's rule will not have a significant
economic impact on a substantial number of small entities, within the
meaning of the RFA.
Under the Clean Water Act, EPA has authority to promulgate criteria
or standards in any case where the Administrator determines that a
revised or new standard is necessary to meet the requirements of the
Act. EPA-promulgated standards are implemented through various water
quality control programs, including the National Pollutant Discharge
Elimination System (NPDES) program, that limits discharges to navigable
waters except in compliance with an EPA permit or permit issued under
an approved State program. The CWA requires that all NPDES permits
include any limits on discharges that are necessary to meet State water
quality standards. The States have discretion in deciding how to meet
the water quality standards and in developing discharge limits as
needed to meet the standards. While State implementation of federally-
promulgated water quality criteria or standards may result in new or
revised discharge limits being placed on small entities, the criteria
or standards themselves do not apply to any discharger, including small
entities.
Today's rule imposes obligations on States included in the NTR but,
as explained above, does not itself establish any requirements that are
directly applicable to small entities. As a result of this action, the
States will need to ensure that permits they issue include any
limitations on dischargers necessary to comply with the water quality
standards established by the criteria in today's rule. In so doing,
States will have a number of discretionary choices associated with
permit writing. While implementation
[[Page 61193]]
of today's rule may ultimately result in some new or revised permit
conditions for some dischargers, including small entities, EPA's action
today does not impose any of these as yet unknown requirements on small
entities.
Furthermore, today's rule results in ambient water quality criteria
for human health that are not more stringent than those formerly
promulgated in the NTR. Therefore, application of today's criteria on
dischargers should not impose any adverse economic impact on small
entities.
6. The Paperwork Reduction Act
The final rule includes no new or additional information collection
activities, therefore, no information collection request was submitted
to OMB for review under the provisions of the Paperwork Reduction Act,
44 U.S.C. 3501 et seq.
7. National Technology Transfer and Advancement Act (NTTAA)
As noted in the proposed rule, Section 12(d) of the National
Technology Transfer and Advancement Act of 1995 (``NTTAA''), Pub. L.
No. 104-113 Sec. 12 (d) (15 U.S.C. 272 note) directs EPA to use
voluntary consensus standards in its regulatory activities unless to do
so would be inconsistent with applicable law or otherwise impractical.
Voluntary consensus standards are technical standards (e.g., materials
specifications, test methods, sampling procedures, business practices,
etc.) that are developed or adopted by voluntary consensus standards
bodies. The NTTAA directs EPA to provide Congress through OMB,
explanations when the Agency decides not to use available and
applicable voluntary consensus standards.
This action does not involve technical standards. Therefore, EPA
did not consider the use of any voluntary consensus standards.
8. E.O. 13045--Protection of Children From Environmental Health Risks
and Safety Risks
Executive Order 13045: ``Protection of Children from Environmental
Health Risks and Safety Risks'' (62 FR 19885, April 23, 1997) applies
to any rule that: (1) is determined to be ``economically significant''
as defined under E.O. 12866, and (2) concerns an environmental health
or safety risk that EPA has reason to believe may have a
disproportionate effect on children. If the regulatory action meets
both criteria, the Agency must evaluate the environmental health or
safety effects of the planned rule on children, and explain why the
planned regulation is preferable to other potentially effective and
reasonablely feasible alternatives considered by the Agency.
This final rule is not subject to the Executive Order because it is
not economically significant as defined in E.O. 12866. Further, the
Agency does not have reason to believe the environmental health risks
or safety risks addressed by this action present a disproportionate
risk to children. We have evaluated current data regarding the
environmental health effects of PCBs on children. While there are no
available data showing that children have an increased risk of cancer
from PCBs, the Agency did consider the fact that children are a highly
exposed population in the risk assessment used as the basis for this
rule. Based on estimates of average daily intake for nursing infants,
an average daily intake of PCBs for a 5-kg nursing infant would be
about triple the average adult intake and approximately 50-fold higher
when adjusted for body weight. Thus, the Agency considers nursing
infants to be an important potentially highly exposed population.
However, since the Agency considers carcinogenicity a function of total
dose over a lifetime of 70 years the increased intake for nursing
infants should not result in a disproportionate lifetime risk.
Furthermore, the final water quality criteria in this rule are based on
an upper bound cancer potency factor to be protective of sensitive
subpopulations, including children.
Peer reviewed data on the developmental toxicity of PCBs to Rhesus
monkeys is available in EPA's Integrated Risk Information System (IRIS)
(available at: www.epa.gov/ngispgm3/iris/irisdat). Reference doses
(RfDs) for non-cancer effects for particular Aroclors are available on
IRIS, but criteria based on these RFDs would be less stringent than
those promulgated today based on carcinogenicity.
The Agency is also aware of other human studies concerning the
effects of PCBs on child development in locations where the mothers are
consumers of fish contaminated with PCBs. However, the currently
available data on children's risks to PCBs have not to date been
sufficient to make full quantitative assessments of risk and
preliminary analyses have not shown effects at levels that would
suggest that the criteria in this rule are not protective. (Johnson et.
al., 1999).
9. Congressional Review Act
The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the
Small Business Regulatory Enforcement Fairness Act of 1996, generally
provides that before a rule may take effect, the agency promulgating
the rule must submit a rule report, which includes a copy of the rule,
to each House of the Congress and to the Comptroller General of the
United States. EPA will submit a report containing this rule and other
required information to the U.S. Senate, the U.S. House of
Representatives, and the Comptroller General of the United States prior
to publication of the rule in the Federal Register. A major rule cannot
take effect until 60 days after it is published in the Federal
Register. This action is not a ``major rule'' as defined by 5 U.S.C.
804(2). This rule will be effective December 9, 1999.
List of Subjects in 40 CFR Part 131
Environmental protection, Toxic pollutants, Water pollution
control, Water quality standards.
Dated: September 27, 1999.
Carol M. Browner,
Administrator.
For the reasons set out in the preamble title 40, chapter I, part
131 of the Code of Federal Regulations is amended as follows:
PART 131--WATER QUALITY STANDARDS
1. The authority citation for part 131 continues to read as
follows:
Authority: 33 U.S.C. 1251 et seq.
2. Section 131.36 is amended as follows:
a. By revising paragraph (b)(1):
b. Paragraph (d)(3)(ii) is amended by revising entries ``B2'' and
``C2'' under the heading ``Applicable Criteria'' as set forth below;
and
c. Paragraph (d)(9)(ii) is amended by revising entry ``B2'' under
the heading ``Applicable Criteria'' as set forth below.
The revisions read as follows:
Sec. 131.36 Toxics criteria for those States not complying with Clean
Water Act Section 303(c)(2)(B).
* * * * *
(b)(1) EPA's Section 304(a) criteria for Priority Toxic Pollutants.
[[Page 61194]]
--------------------------------------------------------------------------------------------------------------------------------------------------------
A B Freshwater C Saltwater D Human Health (10-6 risk for
----------------------------------------------------------------------------------------------------------------------- carcinogens) For consumption of:
Criterion Criterion ---------------------------------
Criterion Continuous Criterion Continuous Water &
(#) Compound CAS Number Maximum Conc. Conc. d (d (d (μg/ m>g/L) d (μg/ m>g/L) (μg/L) (μg/L)
B1 B2 C1 C2 D1 D2
--------------------------------------------------------------------------------------------------------------------------------------------------------
1 Antimony................... 7440360 ............... ............... ............... ............... 14 a 4300 a
2 Arsenic.................... 7440382 360 m 190 m 69 m 36 m 0.018 abc 0.14 abc
3 Beryllium.................. 7440417 ............... ............... ............... ............... n n
4 Cadmium.................... 7440439 3.7 e 1.0 e 42 m 9.3 m n n
5a Chromium (III)............. 16065831 550 e 180 e ............... ............... n n
b Chromium (VI).............. 18540299 15 m 10 m 1100 m 50 m n n
6 Copper..................... 7440508 17 e 11 e 2.4 m 2.4 m ............... ...............
7 Lead....................... 7439921 65 e 2.5 e 210 m 8.1 m n n
8 Mercury.................... 7439976 2.1 m 0.012 ip 1.8 m 0.025 ip 0.14 0.15
9 Nickel..................... 7440020 1400 e 160 e 74 m 8.2 m 610 a 4600 a
10 Selenium................... 7782492 20 p 5 p 290 m 71 m n n
11 Silver..................... 7440224 3.4 e ............... 1.9 m ............... ............... ...............
12 Thallium................... 7440280 ............... ............... ............... ............... 1.7 a 6.3 a
13 Zinc....................... 7440666 110 e 100 e 90 m 81 m
14 Cyanide.................... 57125 22 5.2 1 1 700 a 220000 aj
15 Asbestos................... 1332214 ............... ............... ............... ............... 7,000,000 ...............
fibers/L k
16 2,3,7,8-TCDD (Dioxin)...... 1746016 ............... ............... ............... ............... 0.000000013 c 0.000000014 c
17 Acrolein................... 107028 ............... ............... ............... ............... 320 780
18 Acrylonitrile.............. 107131 ............... ............... ............... ............... 0.059 ac 0.66 ac
19 Benzene.................... 71432 ............... ............... ............... ............... 1.2 ac 71 ac
20 Bromoform.................. 75252 ............... ............... ............... ............... 4.3 ac 360 ac
21 Carbon Tetrachloride....... 56235 ............... ............... ............... ............... 0.25 ac 4.4 ac
22 Chlorobenzene.............. 108907 ............... ............... ............... ............... 680 a 21000 aj
23 Chlorodibromomethane....... 124481 ............... ............... ............... ............... 0.41 ac 34 ac
24 Chloroethane............... 75003 ............... ............... ............... ............... ............... ...............
25 2-Chloroethylvinyl Ether... 110758 ............... ............... ............... ............... ............... ...............
26 Chloroform................. 67663 ............... ............... ............... ............... 5.7 ac 470 ac
27 Dichlorobromomethane....... 75274 ............... ............... ............... ............... 0.27 ac 22 ac
28 1,1-Dichloroethane......... 75343 ............... ............... ............... ............... ............... ...............
29 1,2-Dichloroethane......... 107062 ............... ............... ............... ............... 0.38 ac 99 ac
30 1,1-Dichloroethylene....... 75354 ............... ............... ............... ............... 0.057 ac 3.2 ac
31 1,2-Dichloropropane........ 78875 ............... ............... ............... ............... ............... ...............
32 1,3-Dichloropropylene...... 542756 ............... ............... ............... ............... 10 a 1700 a
33 Ethylbenzene............... 100414 ............... ............... ............... ............... 3100 a 29000 a
34 Methyl Bromide............. 74839 ............... ............... ............... ............... 48 a 4000 a
35 Methyl Chloride............ 74873 ............... ............... ............... ............... n n
36 Methylene Chloride......... 75092 ............... ............... ............... ............... 4.7 ac 1600 ac
37 1,1,2,2-Tetrachloroethane.. 79345 ............... ............... ............... ............... 0.17 ac 11 ac
38 Tetrachloroethylene........ 127184 ............... ............... ............... ............... 0.8 c 8.85 c
39 Toluene.................... 108883 ............... ............... ............... ............... 6800 a 200000 a
40 1,2-Trans-Dichloroethylene. 156605 ............... ............... ............... ............... ............... ...............
41 1,1,1-Trichloroethane...... 71556 ............... ............... ............... ............... n n
42 1,1,2-Trichloroethane...... 79005 ............... ............... ............... ............... 0.60 ac 42 ac
43 Trichloroethylene.......... 79016 ............... ............... ............... ............... 2.7 c 81 c
44 Vinyl Chloride............. 75014 ............... ............... ............... ............... 2 c 525 c
45 2-Chlorophenol............. 95578 ............... ............... ............... ............... ............... ...............
46 2,4-Dichlorophenol......... 120832 ............... ............... ............... ............... 93 a 790 aj
47 2,4-Dimethylphenol......... 105679 ............... ............... ............... ............... ............... ...............
48 2-Methyl-4,6-Dinitrophenol. 534521 ............... ............... ............... ............... 13.4 765
49 2,4-Dinitrophenol.......... 51285 ............... ............... ............... ............... 70 a 14000 a
50 2-Nitrophenol.............. 88755 ............... ............... ............... ............... ............... ...............
51 4-Nitrophenol.............. 100027 ............... ............... ............... ............... ............... ...............
52 3-Methyl-4-Chlorophenol.... 59507 ............... ............... ............... ............... ............... ...............
53 Pentachlorophenol.......... 87865 20 f 13 f 13 7.9 0.28 ac 8.2 acj
54 Phenol..................... 108952 ............... ............... ............... ............... 21000 a 4600000 aj
55 2,4,6-Trichlorophenol...... 88062 ............... ............... ............... ............... 2.1 ac 6.5 ac
56 Acenaphthene............... 83329 ............... ............... ............... ............... ............... ...............
57 Acenaphthylene............. 208968 ............... ............... ............... ............... ............... ...............
58 Anthracene................. 120127 ............... ............... ............... ............... 9600 a 110000 a
59 Benzidine.................. 92875 ............... ............... ............... ............... 0.00012 ac 0.00054 ac
60 Benzo(a)Anthracene......... 56553 ............... ............... ............... ............... 0.0028 c 0.031 c
61 Benzo(a)Pyrene............. 50328 ............... ............... ............... ............... 0.0028 c 0.031 c
62 Benzo(b)Fluoranthene....... 205992 ............... ............... ............... ............... 0.0028 c 0.031 c
63 Benzo(ghi)Perylene......... 191242 ............... ............... ............... ............... ............... ...............
64 Benzo(k)Fluoranthene....... 207089 ............... ............... ............... ............... 0.0028 c 0.031 c
65 Bis(2-Chloroethoxy)Methane. 111911 ............... ............... ............... ............... ............... ...............
66 Bis(2-Chloroethyl)Ether.... 111444 ............... ............... ............... ............... 0.031 ac 1.4 ac
67 Bis(2-Chloroisopropyl)Ether 108601 ............... ............... ............... ............... 1400 a 170000 a
68 Bis(2-Ethylhexyl)Phthalate. 117817 ............... ............... ............... ............... 1.8 ac 5.9 ac
69 4-Bromophenyl Phenyl Ether. 101553 ............... ............... ............... ............... ............... ...............
70 Butylbenzyl Phthalate...... 85687 ............... ............... ............... ............... ............... ...............
71 2-Chloronaphthalene........ 91587 ............... ............... ............... ............... ............... ...............
72 4-Chlorophenyl Phenyl Ether 7005723 ............... ............... ............... ............... ............... ...............
73 Chrysene................... 218019 ............... ............... ............... ............... 0.0028 c 0.031 c
[[Page 61195]]
74 Dibenzo(ah)Anthracene...... 53703 ............... ............... ............... ............... 0.0028 c 0.031 c
75 1,2-Dichlorobenzene........ 95501 ............... ............... ............... ............... 2700 a 17000 a
76 1,3-Dichlorobenzene........ 541731 ............... ............... ............... ............... 400 2600
77 1,4-Dichlorobenzene........ 106467 ............... ............... ............... ............... 400 2600
78 3,3'-Dichlorobenzidine..... 91941 ............... ............... ............... ............... 0.04 ac 0.077 ac
79 Diethyl Phthalate.......... 84662 ............... ............... ............... ............... 23000 a 120000 a
80 Dimethyl Phthalate......... 131113 ............... ............... ............... ............... 313000 2900000
81 Di-n-Butyl Phthalate....... 84742 ............... ............... ............... ............... 2700 a 12000 a
82 2,4-Dinitrotoluene......... 121142 ............... ............... ............... ............... 0.11 c 9.1 c
83 2,6-Dinitrotoluene......... 606202 ............... ............... ............... ............... ............... ...............
84 Di-n-Octyl Phthalate....... 117840 ............... ............... ............... ............... ............... ...............
85 1,2-Diphenylhydrazine...... 122667 ............... ............... ............... ............... 0.040 ac 0.54 ac
86 Fluoranthene............... 206440 ............... ............... ............... ............... 300 a 370 a
87 Fluorene................... 86737 ............... ............... ............... ............... 1300 a 14000 a
88 Hexachlorobenzene.......... 118741 ............... ............... ............... ............... 0.00075 ac 0.00077 ac
89 Hexachlorobutadiene........ 87683 ............... ............... ............... ............... 0.44 ac 50 ac
90 Hexachlorocyclopentadiene.. 77474 ............... ............... ............... ............... 240 a 17000 aj
91 Hexachloroethane........... 67721 ............... ............... ............... ............... 1.9 ac 8.9 ac
92 Indeno(1,2,3-cd)Pyrene..... 193395 ............... ............... ............... ............... 0.0028 c 0.031 c
93 Isophorone................. 78591 ............... ............... ............... ............... 8.4 ac 600 ac
94 Naphthalene................ 91203 ............... ............... ............... ............... ............... ...............
95 Nitrobenzene............... 98953 ............... ............... ............... ............... 17 a 1900 aj
96 N-Nitrosodimethylamine..... 62759 ............... ............... ............... ............... 0.00069 ac 8.1 ac
97 N-Nitrosodi-n-Propylamine.. 621647 ............... ............... ............... ............... ............... ...............
98 N-Nitrosodiphenylamine..... 86306 ............... ............... ............... ............... 5.0 ac 16 ac
99 Phenanthrene............... 85018 ............... ............... ............... ............... ............... ...............
100 Pyrene..................... 129000 ............... ............... ............... ............... 960 a 11000 a
101 1,2,4-Trichlorobenzene..... 120821 ............... ............... ............... ............... ............... ...............
102 Aldrin..................... 309002 3 g ............... 1.3 g ............... 0.00013 ac 0.00014 ac
103 alpha-BHC.................. 319846 ............... ............... ............... ............... 0.0039 ac 0.013 ac
104 beta-BHC................... 319857 ............... ............... ............... ............... 0.014 ac 0.046 ac
105 gamma-BHC.................. 58899 2 g 0.08 g 0.16 g ............... 0.019 c 0.063 c
106 delta-BHC.................. 319868 ............... ............... ............... ............... ............... ...............
107 Chlordane.................. 57749 2.4 g 0.0043 g 0.09 g 0.004 g 0.00057 ac 0.00059 ac
108 4-4'-DDT................... 50293 1.1 g 0.001 g 0.13 g 0.001 g 0.00059 ac 0.00059 ac
109 4,4'-DDE................... 72559 ............... ............... ............... ............... 0.00059 ac 0.00059 ac
110 4,4'-DDD................... 72548 ............... ............... ............... ............... 0.00083 ac 0.00084 ac
111 Dieldrin................... 60571 2.5 g 0.0019 g 0.71 g 0.0019 g 0.00014 ac 0.00014 ac
112 alpha-Endosulfan........... 959988 0.22 g 0.056 g 0.034 g 0.0087 g 0.93 a 2.0 a
113 beta-Endosulfan............ 33213659 0.22 g 0.056 g 0.034 g 0.0087 g 0.93 a 2.0 a
114 Endosulfan Sulfate......... 1031078 ............... ............... ............... ............... 0.93 a 2.0 a
115 Endrin..................... 72208 0.18 g 0.0023 g 0.037 g 0.0023 g 0.76 a 0.81 aj
116 Endrin Aldehyde............ 7421934 ............... ............... ............... ............... 0.76 a 0.81 aj
117 Heptachlor................. 76448 0.52 g 0.0038 g 0.053 g 0.0036 g 0.00021 ac 0.00021 ac
118 Heptachlor Epoxide......... 1024573 0.52 g 0.0038 g 0.053 g 0.0036 g 0.00010 ac 0.00011 ac
119 PCB-1242................... 53469219 ............... 0.014 g ............... 0.03 g ............... ...............
120 PCB-1254................... 11097691 ............... 0.014 g ............... 0.03 g ............... ...............
121 PCB-1221................... 11104282 ............... 0.014 g ............... 0.03 g ............... ...............
122 PCB-1232................... 11141165 ............... 0.014 g ............... 0.03 g ............... ...............
123 PCB-1248................... 12672296 ............... 0.014 g ............... 0.03 g ............... ...............
124 PCB-1260................... 11096825 ............... 0.014 g ............... 0.03 g ............... ...............
125a PCB-1016................... 12674112 ............... 0.014 g ............... 0.03 g ............... ...............
125b Polychlorinated biphenyls ............... ............... ............... ............... ............... 0.00017 q 0.00017 q
(PCBs)...................
126 Toxaphene.................. 8001352 0.73 0.0002 0.21 0.0002 0.00073 ac 0.00075 ac
Total Number of Criteria (h) ............... 24 29 23 27 85 84
=...........................
--------------------------------------------------------------------------------------------------------------------------------------------------------
Footnotes
a. Criteria revised to reflect current agency q1* or
RfD, as contained in the Integrated Risk Information System (IRIS).
The fish tissue bioconcentration factor (BCF) from the 1980 criteria
documents was retained in all cases.
b. The criteria refers to the inorganic form only.
c. Criteria in the matrix based on carcinogenicity
(10-6 risk). For a risk level of 10-5, move
the decimal point in the matrix value one place to the right.
d. Criteria Maximum Concentration (CMC) = the highest
concentration of a pollutant to which aquatic life can be exposed
for a short period of time (1-hour average) without deleterious
effects. Criteria Continuous Concentration (CCC) = the highest
concentration of a pollutant to which aquatic life can be exposed
for an extended period of time (4 days) without deleterious effects.
μg/L = micrograms per liter.
e. Freshwater aquatic life criteria for these metals are
expressed as a function of total hardness (mg/L as
CaCO3), the pollutant's water effect ratio (WER) as
defined in Sec. 131.36(c) and multiplied by an appropriate dissolved
conversion factor as defined in Sec. 131.36(b)(2).
[[Page 61196]]
For comparative purposes, the values displayed in this matrix are
shown as dissolved metal and correspond to a total hardness of 100
mg/L and a water effect ratio of 1.0.
f. Freshwater aquatic life criteria for pentachlorophenol are
expressed as a function of pH, and are calculated as follows. Values
displayed above in the matrix correspond to a pH of 7.8.
CMC = exp(1.005(pH)-4.830)
CCC = exp(1.005(pH)-5.290)
g. Aquatic life criteria for these compounds were issued in 1980
utilizing the 1980 Guidelines for criteria development. The acute
values shown are final acute values (FAV) which by the 1980
Guidelines are instantaneous values as contrasted with a CMC which
is a one-hour average.
h. These totals simply sum the criteria in each column. For
aquatic life, there are 31 priority toxic pollutants with some type
of freshwater or saltwater, acute or chronic criteria. For human
health, there are 85 priority toxic pollutants with either ``water +
fish'' or ``fish only'' criteria. Note that these totals count
chromium as one pollutant even though EPA has developed criteria
based on two valence states. In the matrix, EPA has assigned numbers
5a and 5b to the criteria for chromium to reflect the fact that the
list of 126 priority toxic pollutants includes only a single listing
for chromium.
i. If the CCC for total mercury exceeds 0.012 μg/l more
than once in a 3-year period in the ambient water, the edible
portion of aquatic species of concern must be analyzed to determine
whether the concentration of methyl mercury exceeds the FDA action
level (1.0 mg/kg). If the FDA action level is exceeded, the State
must notify the appropriate EPA Regional Administrator, initiate a
revision of its mercury criterion in its water quality standards so
as to protect designated uses, and take other appropriate action
such as issuance of a fish consumption advisory for the affected
area.
j. No criteria for protection of human health from consumption
of aquatic organisms (excluding water) was presented in the 1980
criteria document or in the 1986 Quality Criteria for Water.
Nevertheless, sufficient information was presented in the 1980
document to allow a calculation of a criterion, even though the
results of such a calculation were not shown in the document.
k. The criterion for asbestos is the MCL (56 FR 3526, January
30, 1991).
l. [Reserved: This letter not used as a footnote.]
m. Criteria for these metals are expressed as a function of the
water effect ratio, WER, as defined in 40 CFR 131.36(c).
CMC = column B1 or C1 value x WER
CCC = column B2 or C2 value x WER
n. EPA is not promulgating human health criteria for this
contaminant. However, permit authorities should address this
contaminant in NPDES permit actions using the State's existing
narrative criteria for toxics.
o. [Reserved: This letter not used as a footnote.]
p. Criterion expressed as total recoverable.
q. This criterion applies to total PCBs (e.g., the sum of all
congener or isomer or homolog or Aroclor analyses).
General Notes
1. This chart lists all of EPA's priority toxic pollutants
whether or not criteria recommendations are available. Blank spaces
indicate the absence of criteria recommendations. Because of
variations in chemical nomenclature systems, this listing of toxic
pollutants does not duplicate the listing in Appendix A of 40 CFR
Part 423. EPA has added the Chemical Abstracts Service (CAS)
registry numbers, which provide a unique identification for each
chemical.
2. The following chemicals have organoleptic based criteria
recommendations that are not included on this chart (for reasons
which are discussed in the preamble): copper, zinc, chlorobenzene,
2-chlorophenol, 2,4-dichlorophenol, acenaphthene, 2,4-
dimethylphenol, 3-methyl-4-chlorophenol, hexachlorocyclopentadiene,
pentachlorophenol, phenol.
3. For purposes of this rulemaking, freshwater criteria and
saltwater criteria apply as specified in 40 CFR 131.36(c).
Note to paragraph (b)(1): On April 14, 1995, the Environmental
Protection Agency issued a stay of certain criteria in paragraph
(b)(1) of this section as follows: the criteria in columns B and C
for arsenic, cadmium, chromium (VI), copper, lead, nickel, silver,
and zinc; the criteria in B1 and C1 for mercury; the criteria in
column B for chromium (III); and the criteria in column C for
selenium. The stay remains in effect until further notice.
* * * * * * *
(d) * * *
(3) * * *
(ii) * * *
------------------------------------------------------------------------
Use classification Applicable criteria
------------------------------------------------------------------------
* * * *
* * *
Column B2--all except #105,
107, 108, 111, 112, 113, 115,
117, 118, 119, 120, 121, 122,
123, 124, and 125a.
* * * *
* * *
Column C2--all except #105,
107, 108, 111, 112, 113, 115,
117, 118, 119, 120, 121, 122,
123, 124, and 125a.
* * * *
* * *
------------------------------------------------------------------------
* * * * * * *
(9) * * *
(ii) * * *
------------------------------------------------------------------------
Use classification Applicable criteria
------------------------------------------------------------------------
* * * *
* * *
Column B2--all except #9, 13,
105, 107, 108, 111-113, 115,
117, 119-125a and 126; and
* * * *
* * *
------------------------------------------------------------------------
[FR Doc. 99-25559 Filed 11-8-99; 8:45 am]
BILLING CODE 6560-50-P
This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.