[Federal Register Volume 64, Number 216 (Tuesday, November 9, 1999)]
[Rules and Regulations]
[Pages 61182-61196]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-25559]



[[Page 61181]]

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Part II





Environmental Protection Agency





_______________________________________________________________________



40 CFR Part 131



Water Quality Standards; Establishment of Numeric Criteria for Priority 
Toxic Pollutants; States' Compliance--Revision of Polychlorinated 
Biphenyls (PCBs) Criteria; Final Rule

  Federal Register / Vol. 64, No. 216 / Tuesday, November 9, 1999 / 
Rules and Regulations  

[[Page 61182]]



ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 131

[FRL-6450-5]
RIN 2040-AD27


Water Quality Standards; Establishment of Numeric Criteria for 
Priority Toxic Pollutants; States' Compliance--Revision of 
Polychlorinated Biphenyls (PCBs) Criteria

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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

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.

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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