[Federal Register Volume 61, Number 205 (Tuesday, October 22, 1996)]
[Proposed Rules]
[Pages 54748-54756]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-26918]


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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 132

[FRL-5617-8]


Proposed Revisions to the Polychlorinated Biphenyl Criteria for 
Human Health and Wildlife for the Water Quality Guidance for the Great 
Lakes System

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule.

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SUMMARY: EPA is proposing revisions to the polychlorinated biphenyl 
(PCB) ambient water quality criteria for human health and wildlife for 
the final Water Quality Guidance for the Great Lakes System (the 
Guidance). The Guidance was published on March 23, 1995. Following 
publication, several industries and trade associations challenged the 
human health and wildlife criteria for PCBs in the Guidance. Among the 
issues they raised was the equation used to calculate the weighted 
geometric mean baseline bioaccumulation factor (BAF) for PCBs. EPA re-
examined the issue, and decided that a different approach for 
calculating a composite baseline BAF would be preferable because it 
would be more consistent with the definition of bioaccumulation factors 
since it more appropriately relates the concentrations of the PCB 
congeners in tissue to the concentrations of the PCB congeners in 
water. The proposed revisions are limited to the method for deriving a 
composite BAF for PCBs and for deriving a composite octanol-water 
partition coefficient (Kow) for PCBs. The human health cancer 
criteria for PCBs would change from 3.9 E-6 ug/L to 6.8 E-6 ug/L. The 
wildlife criteria for PCBs would change from 7.4 E-5 ug/L to 1.2 E-4 
ug/L. EPA believes the proposed revisions more accurately represent the 
numerical limits necessary to protect human health and wildlife in the 
Great Lakes System. Finally, EPA is not proposing to revise any other 
aspect of the BAFs for PCBs or the PCB criteria for human health and 
wildlife.

DATES: EPA will accept public comments on the proposal until November 
21, 1996.

ADDRESSES: An original and 4 copies of all comments on the proposal 
should be addressed to Mark Morris (4301), U.S. EPA, 401 M Street., SW, 
Washington, D.C. 20460.

FOR FURTHER INFORMATION CONTACT: Mark Morris (4301), U.S. EPA, 401 M 
Street, SW, Washington, D.C. 20460 (202-260-0312).

SUPPLEMENTARY INFORMATION:

I. Introduction

A. Potentially Affected Entities

    Entities potentially affected by this action are those discharging 
pollutants to waters of the United States in the Great Lakes System. 
Potentially affected categories and entities include:

------------------------------------------------------------------------
                                     Examples of potentially affected   
            Category                             entities               
------------------------------------------------------------------------
Industry.......................  Industries discharging PCBs to waters  
                                  in the Great Lakes System as defined  
                                  in 40 CFR 132.2.                      
Municipalities.................  Publicly-owned treatment works         
                                  discharging PCBs to waters of the     
                                  Great Lakes System as defined in 40   
                                  CFR 132.2.                            
States and Tribes..............  Great Lakes States and Tribes must     
                                  adopt criteria consistent with EPA's  
                                  criteria by March 1997.               
------------------------------------------------------------------------

    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. To determine whether 
your facility may be affected by this action, you should examine the 
definition of Great Lakes System in 40 CFR 132.2 and examine 40 CFR 
132.2 which describes the purpose of water quality standards such as 
those established in this rule. If you have any questions regarding the 
applicability of this action to a particular entity, consult the person 
listed in the preceding FOR FURTHER INFORMATION CONTACT section.

B. Great Lakes Water Quality Guidance

    In March 1995, EPA promulgated the final Water Quality Guidance for 
the Great Lakes System (the Guidance) required under section 118(c)(2) 
of the Clean Water Act, 33 U.S.C. 1268(c)(2). See 60 FR 15366-425 
(March 23, 1995). The Guidance protects the waters of the Great Lakes 
and their tributaries by establishing water quality criteria for 29 
pollutants to protect aquatic life, wildlife and human health, and 
detailed methodologies to develop criteria for additional pollutants. 
It also establishes implementation procedures to help Great Lakes 
States and Tribes develop more consistent, enforceable water-quality 
based effluent limits in discharge permits for the Great Lakes System. 
For a description of the environmental significance of the Great Lakes 
System and the serious environmental threats it faces (particularly 
from persistent, bioaccumulative chemicals), see 58 FR 20802.
    The ambient water quality criteria (AWQC) included in the Guidance 
to protect human health and wildlife set maximum ambient concentrations 
for harmful pollutants to be met in all waters in the Great Lakes 
System. See 40 CFR Part 132, Tables 3 and 4. Great Lakes States and 
Tribes must adopt criteria consistent with EPA's criteria by March of 
1997. CWA section 118(c)(2)(c). If any State or Tribe fails to meet 
that deadline, EPA must

[[Page 54749]]

promulgate criteria that will apply in that State or Tribe's 
jurisdiction. Id. Once the criteria take effect, permits for discharges 
of such pollutants into the Great lakes System must include limits as 
necessary to attain the criteria.
    EPA promulgated human health and wildlife criteria for a class of 
closely-related toxic pollutants known as polychlorinated biphenyls 
(``PCBs''). The PCB criteria for human health and wildlife incorporate 
``bioaccumulation factors'' (``BAFs'') which reflect the fact that PCBs 
magnify at several steps in aquatic food chains, so that humans and 
wildlife eating fish from the Great Lakes can be exposed to PCB 
concentrations many times higher than the PCB concentration in the 
waters of the Lakes. Different members of the class of PCBs (called 
``congeners'') have differing potentials to bioaccumulate. In the final 
Guidance, EPA derived a single baseline BAF (explained further below) 
for PCBs by computing a weighted geometric mean baseline BAF from the 
BAFs for approximately 50 PCB congeners.
    Several industries and trade associations challenged the human 
health and wildlife criteria for PCBs. AISI v. EPA, D.C. Cir. No. 95-
1348 and consolidated cases. Among the issues they raised was the 
equation used to calculate the weighted geometric mean baseline BAF for 
PCBs. The AISI petitioners alleged that the equation was mathematically 
inappropriate for a variety of reasons. EPA re-examined the issue, and 
decided, for reasons set out in section III below, that a different 
approach for calculating a composite baseline BAF would be preferable. 
Consequently, EPA is proposing to revise the approach for calculating 
the composite baseline BAF for PCBs and for deriving a composite 
Kow for PCBs. The new approach produces both a new composite 
baseline BAF and different BAFs for use in the derivation of human 
health and wildlife criteria. EPA has recalculated the human health and 
wildlife criteria using the new BAFs and is proposing to revise the 
criteria for PCBs codified in Tables 3 and 4 to Part 132.
    As explained in more detail below, EPA is not proposing any other 
revisions to the criteria for PCBs. Moreover, EPA does not intend to 
respond to comments addressing other issues.

II. Background

A. EPA's Methodology for Deriving BAFs

    The human health and wildlife criteria establish ambient 
concentrations of pollutants which will protect humans and wildlife 
species from adverse impacts due to the ingestion of both aquatic 
organisms and water. To establish the criteria, EPA obtained data on 
health effects thresholds and derived bioaccumulation factors for 
individual pollutants. EPA also obtained data on rates of food and 
water consumption for humans and wildlife species.
    As explained in the preamble and supporting documents for the final 
Guidance, bioaccumulation refers to the uptake and retention of a 
pollutant by an aquatic organism from surrounding water and from food. 
For certain pollutants, uptake through the food chain is the most 
important route of exposure for humans and wildlife, as such pollutants 
magnify at some steps in the aquatic food chain, so that humans and 
wildlife can consume aquatic organisms containing concentrations of 
pollutants many times higher than the concentrations of the pollutants 
in Great Lakes waters. For a more complete discussion of 
bioaccumulation, refer to 58 FR 20803.
    The BAFs in the Guidance compare concentrations of pollutants 
measured in water to concentrations of the same pollutant measured in 
fish tissue. Under the methodology for the Guidance, the derivation of 
a BAF for a non-polar organic pollutant that is to be used for 
calculating AWQC involves two general steps. The first step is deriving 
the baseline BAF for the pollutant of interest. For PCBs, this is 
performed by adjusting the field-measured BAF to reflect the freely 
dissolved fraction of the pollutant in the water at the site measured 
and the lipid content of the organism assessed. The second step 
involves calculating a BAF that takes into account the freely-dissolved 
fraction of the chemical in the water and lipid content of the 
organism(s) at the site where the AWQC would apply. For a more detailed 
discussion on this two step process and for additional information on 
the importance of expressing the baseline BAF on a freely-dissolved and 
lipid-normalized basis, refer to the Great Lakes Water Quality 
Technical Support Document for the Procedure to Determine 
Bioaccumulation Factors (``TSD for BAFs'') (EPA-820-B-95-005).
    An important factor in the derivation of a BAF for an individual 
PCB congener is the Kow for that pollutant. The Kow is a 
measurement of the affinity of a pollutant to partition between the 
lipids (fatty tissues) of an aquatic organism and water. The higher the 
Kow, all other factors being constant, the greater the affinity 
for the pollutant to concentrate in fish tissue. Each of the PCB 
congeners has a Kow value. The Kow values are usually 
reported as log Kows for each congener. When deriving BAFs for 
individual PCB congeners, the congener-specific Kow is used for 
estimating the freely dissolved fraction of the PCB congener in the 
water. When deriving a composite baseline BAF for all PCBs, it is 
necessary to use a composite Kow value for the composite BAF. This 
composite Kow is needed for estimating the freely dissolved 
fraction of the class of PCBs in the Great Lakes waters.

B. BAFs for PCBs in the Final Guidance

    EPA based the PCB BAFs in the final Guidance on a field study 
conducted in the Great Lakes by Oliver and Niimi (1988). The study 
collected data on numerous PCB congeners, and EPA derived separate 
baseline BAFs for these congeners using separate, congener-specific 
Kows. EPA, however, needed to derive a composite BAF representing 
all congeners in order to calculate AWQC for human health and wildlife. 
This is the case because there is a single ``cancer potency factor'' 
which is used for evaluating human health cancer risk for all PCBs. 
Similarly, for wildlife, there is a single toxicity factor which is 
used in the derivation of the wildlife criteria. Consequently, 
composite BAFs were needed in order to be consistent with the toxicity 
data available to derive human health and wildlife criteria.
    In response to comments on a notice of data availability (August 
30, 1994, 59 FR 44678), EPA derived a composite baseline BAF for PCBs 
for trophic level 3 and for trophic level 4 by computing a weighted 
geometric mean of the BAFs for individual PCB congeners using the 
following equation:
    Weighted geometric mean=10 Mean log BAF
    [GRAPHIC] [TIFF OMITTED] TP22OC96.000
    
Where:

Wi=concentration of PCBs in ng/g for each congener in fish tissue.
log BAFi=log BAF as reported in Table F-1 of TSD for BAFs (logs are to 
base 10).

    The weighted geometric mean BAF for trophic level 3 was 55,281,000 
and 116,553,000 for trophic level 4.
    As discussed above, when deriving a composite BAF for PCBs it is 
necessary to use a composite Kow. In the final Guidance, a 
weighted geometric mean Kow of 3,885,000 (mean log Kow of 
6.589) was estimated by weighting the log Kows for the individual 
PCB congeners by the concentrations of the PCB congeners in fish. The 
mean log Kow of 6.589 was then used when estimating the freely 
dissolved fraction for PCBs. The log

[[Page 54750]]

Kows for the individual PCB congeners used in the final Guidance 
came from Hawker and Connell (1988).
    Using these composite baseline BAFs and the mean log Kow of 
6.589, EPA derived BAFs of 520,900 for trophic level 3 and 1,871,000 
for trophic level 4 for use in calculating human health criteria. The 
PCB human health cancer criteria derived using these BAFs was 3.9E-6 
g/L. For wildlife, the BAF was 1,850,000 for trophic level 3 
and 6,224,000 for trophic level 4 for use in calculating wildlife 
criteria. The PCB wildlife criterion derived using these BAFs was 7.4E-
5 g/L.
    Various industries and trade associations challenged the human 
health and wildlife criteria for PCBs. AISI v. EPA, D.C. Cir. No. 95-
1348 and consolidated cases. Among the issues they raised was the 
equation used to calculate the baseline BAF using the weighted 
geometric mean for PCBs. The AISI petitioners alleged that the equation 
was mathematically inappropriate for a variety of reasons. As a result 
of this challenge, EPA re-examined the basis for the calculation of the 
composite baseline BAF using the weighted geometric mean. For the 
reasons explained in section III below, EPA has concluded that a 
different approach would be correct. Consequently, EPA has moved the 
Court to remand this issue to the Agency for reconsideration. EPA 
represented in that motion that it would expeditiously propose and take 
final action on the approach used to calculate the composite baseline 
BAF for PCBs. This proposal serves that purpose.
    EPA emphasizes that this proposal is very limited in scope. EPA is 
only requesting comment on the approach used to derive a composite 
baseline BAF for PCBs and the composite Kow used in estimating the 
freely dissolved fraction of PCBs. EPA is not proposing to revise any 
other aspect of the data or methodology underlying the composite 
baseline BAFs for PCBs or any other aspect of the data or methodology 
underlying the human health and wildlife criteria for PCBs. For those 
issues beyond the limited scope of today's proposal, the Agency 
believes that full opportunity for public comment and consideration by 
the Agency was provided in the rulemaking for the Guidance.

III. Proposed Revision to Method for Deriving Baseline BAF for Total 
PCBs

    As discussed previously, the baseline BAF for PCBs in the final 
Guidance was calculated as a weighted geometric mean of the BAFs for 
the individual congeners. EPA is requesting comment on an alternative 
approach for deriving the composite baseline BAF for PCBs. This 
approach uses the sum of all concentrations of PCB congeners in tissue 
and the sum of all concentrations of PCB congeners in the ambient 
water, as reported in Oliver and Niimi (1988), to derive a baseline BAF 
for PCBs (see Table 1). This approach is equivalent to using a weighted 
arithmetic mean of all the BAFs from the PCB congeners, where the 
weights are the concentrations of the PCB congeners in water. EPA 
believes this approach is more consistent with the definition of 
bioaccumulation factors since it more appropriately relates the sum of 
the concentrations of the PCB congeners in tissue to the sum of the 
concentration of the PCB congeners in water. EPA further believes that 
this approach will provide a more accurate prediction of the composite 
BAF for the class of PCBs.
    The derivation of the composite baseline BAFs for PCBs, the revised 
BAF to be used in the calculation of AWQC for wildlife and human 
health, and the PCB criteria for wildlife and humans using the revised 
PCB BAFs are presented below. EPA is requesting comment on the approach 
for deriving the composite baseline BAF and the composite Kow used 
in the derivation of the baseline BAF. EPA is not requesting comment on 
the data used in the derivation of the composite baseline BAF or 
composite Kow or other aspects related to the derivation of the 
human health and wildlife criteria for PCBs. The fish tissue data, 
water column data, and log Kow values used to derive the new 
composite BAF are identical to those used in the final Guidance.

A. Derivation of Baseline BAF for PCBs

    The equations used for deriving the baseline BAFs in this proposal 
are the same as were used in the final Guidance (60 FR 15400 or TSD for 
BAFs). As in the final Guidance, baseline BAFs for PCBs are derived for 
both trophic level 3 and trophic level 4. The equation for deriving a 
baseline BAF when a field-measured BAF is available for a chemical, as 
is the case with PCBs, is (each of the three components for deriving a 
baseline BAF are discussed below):
[GRAPHIC] [TIFF OMITTED] TP22OC96.001

Where:

Measured BAFTt=BAF based on total concentration in tissue and 
water.
fl=fraction of the tissue that is lipid.
ffd=fraction of the total chemical that is freely dissolved in the 
ambient water.
1. Measured PCB BAFTt
    To estimate a measured PCB BAFTt for trophic level 4, 
information is needed on the total concentration of the pollutant in 
the tissue of a trophic level 4 species and the total concentration of 
the chemical in ambient water at the site of sampling. The trophic 
level 4 species used in the final Guidance and this proposal were 
salmonids. To estimate a measured PCB BAFTt for trophic level 
3, information is needed on the total concentration of the chemical in 
the tissue of a trophic level 3 species and the total concentration of 
the chemical in ambient water at the site of sampling. The trophic 
level 3 species used in the final Guidance and in this proposal to 
calculate a BAF for PCBs are sculpins and alewives. The average of the 
values for the sculpins and alewives are used to represent the trophic 
level 3 values. The equation to derive a measured PCB BAFTt 
is:
[GRAPHIC] [TIFF OMITTED] TP22OC96.002

    The total concentration of PCB congeners in fish tissue (salmonids) 
from Table 1 is 4057.3 ng/g and the total concentration of PCB 
congeners in ambient water is 1006.1 pg/L. The average of the total 
concentrations of PCB congeners in tissue from sculpins and alewife 
(trophic level 3 species) from Table 1 is 1393.15 ng/g. The resulting 
measured PCB BAFTt for trophic level 4 is 4,033,000 and 
1,385,000 for trophic level 3 (rounded to 4 significant figures as 
discussed on page G-2 of the TSD for BAFs).

[[Page 54751]]

[GRAPHIC] [TIFF OMITTED] TP22OC96.003


2. Fraction Freely Dissolved
    To determine the fraction of PCBs that are freely dissolved in the 
ambient water requires information on the particulate organic carbon 
(POC) and dissolved organic carbon (DOC) in the ambient water where the 
samples were collected and the Kow of the chemical. The equation 
for estimating the fraction freely dissolved is as follows:
[GRAPHIC] [TIFF OMITTED] TP22OC96.004

Where:
POC=concentration of particulate organic carbon (kg/L).
DOC=concentration of dissolved organic carbon (kg/L).
Kow=n-octanol water partition coefficient for the chemical.

    The log Kows used for the individual PCB congeners reported in 
Table 1 come from Hawker and Connell (1988). As explained above, it is 
necessary to compute a log Kow for use in the deriving the 
fraction freely dissolved for the composite PCB BAF. EPA is today 
proposing to use the median log Kow from the log Kows 
presented in Table 1. The median log Kows for the PCBs congeners 
listed in Table 1 is 6.35 (Kow of 2,238,721). The median, a 
commonly used measure of central tendency, is the ``middle'' value (or 
50th percentile) of a set of measurements arranged in order of 
magnitude. The median has the advantage of not being dependent on the 
shape of the underlying distribution of the variable of interest, in 
this case, the log Kows of the PCB congeners. Also, the median is 
not sensitive to extremely high or low values. EPA is proposing to use 
this value in place of the log Kow of 6.589 used in the final 
Guidance.
    EPA is soliciting comments on an alternative method for deriving a 
composite Kow. The formula for calculating the alternative method 
is:
[GRAPHIC] [TIFF OMITTED] TP22OC96.005

Where:

i=1, 2, * * * n congeners.
Cwt=total concentration of the chemical in water.
Cwfd=freely dissolved concentration of the chemical in water.

    The alternate formula for calculating the composite Kow is 
based on the following equation for calculating the Kow for a 
single congener.
[GRAPHIC] [TIFF OMITTED] TP22OC96.006

    This formula for calculating the Kow for a single congener was 
derived algebraically from the following definition of the fraction of 
a freely dissolved congener, ffd :
[GRAPHIC] [TIFF OMITTED] TP22OC96.007

    In the alternate formula for the composite Kow, the ratio of 
the sum of the total concentrations of the congeners in water over the 
sum of the total freely dissolved concentrations of the congeners in 
water is substituted for the ratio of the total over freely dissolved 
concentrations of the congener in water for a single congener.
    In the final Guidance, the POC value used was 0.0 kg/L and the DOC 
value used was 2.0 x 10-6 kg/L. EPA is not proposing to change 
these values which represent the POC and DOC values from Lake Ontario 
where the Oliver and Niimi samples were collected.
3. Fraction Lipid
    In addition, EPA is not proposing to change the fraction lipid 
content of the salmonids (0.11) or sculpin (0.08) or alewife (0.07) 
that were used in the final Guidance. The average fraction lipid for 
sculpin and alewife is 0.075.
    The freely dissolved fraction used in the final Guidance for 
deriving the composite baseline BAF was 0.4837. This value was based on 
the POC and DOC values presented above and a log Kow of 6.589. The 
fraction freely dissolved in this notice is 0.6907. The differences 
between the fraction freely dissolved in the final Guidance and this 
notice is the use of a different log Kow as explained above.
[GRAPHIC] [TIFF OMITTED] TP22OC96.008

4. Derivation of Baseline PCB BAFs
    Based on the information presented above and using the equation for 
deriving baseline BAFs, EPA today proposes a composite baseline BAF for 
PCBs for trophic level 4 of 53,080,000 and a composite baseline BAF for 
PCBs for trophic level 3 of 26,735,000.

[[Page 54752]]

[GRAPHIC] [TIFF OMITTED] TP22OC96.009



                    Table 1.--Water and Tissue Concentrations and Log KowS for PCB Congeners                    
----------------------------------------------------------------------------------------------------------------
                                                            Tissue conc. (ng/g)                                 
             Congener                Water conc. -----------------------------------------        Log Kow       
                                       (pg/L)        Sculpin       Alewife      Salmonid                        
----------------------------------------------------------------------------------------------------------------
28+31.............................          46             7.8          14             36  5.67                 
18................................          72             5.2          12            4.3  5.24                 
66................................          31            53            61            160  6.20                 
70+76.............................          45            32            50            140  6.17                 
56+60+81..........................           9.7          18            32             74  6.19                 
52................................          63            28            27             62  5.84                 
47+48.............................          41             4.1          18             60  5.82                 
44................................          50            16            23             45  5.75                 
74................................          10            12            12             38  6.20                 
49................................          24            10            14             31  5.85                 
64................................           9.3           9.2          11             28  5.95                 
42................................           3.3           2.8           5.0           10  5.76                 
101...............................         130           140           110            270  6.38                 
84................................          15           110            68            260  6.04                 
118...............................          34            94            58            250  6.74                 
110...............................          55            76            78            230  6.48                 
87+97.............................          21            42            82            200  6.29                 
105...............................          14            39            27            110  6.65                 
95................................          52            31            40             80  6.13                 
85................................           9.4          17            22             58  6.30                 
92................................           5.4          15            22             53  6.35                 
82................................           2.6           6.3          10             29  6.20                 
91................................          40             7.0          12             29  6.13                 
153...............................          50           170            86            430  6.92                 
138...............................          28           110            65            260  6.83                 
149...............................          34            27            69            190  6.67                 
146...............................           3.8          37            21             88  6.89                 
141...............................           8.3          37            23             83  6.82                 
151...............................           2.7          25            15             51  6.64                 
132...............................          17            20            19             39  6.58                 
136...............................          16            13            15             31  6.22                 
180...............................          27           110            48            200  7.36                 
187+182...........................          18            42            30            130  7.19                 
170+190...........................           2.7          54            23             84  7.37                 
183...............................           2.5          31            12             71  7.20                 
177...............................           1.1          11             7.8           36  7.08                 
174...............................           1.9           7.4          12             32  7.11                 
203+196...........................           2.6          29            12             52  7.65                 
194                                          7.8          15             6.7           23  7.80                 
                                   -----------------------------------------------------------------------------
      Totals......................        1006.1        1513.8        1272.5       4057.3  Median=6.35          
----------------------------------------------------------------------------------------------------------------
The tissue and water concentrations are from Oliver and Niimi (1988). The Log Kow values are from Hawker and    
  Connell (1988). Oliver and Niimi (1988) report the concentrations of congeners 22, 16, 33, 17, 32, 53, 40, and
  99 for water and fish tissue, but did not report the concentrations in sculpin and/or alewife. Because the    
  concentrations were not reported for sculpin and alewife they were not included in this table nor in the      
  calculation of the BAF. This is consistent with the approach used in the final Guidance.                      

B. Calculation of BAF for Use in AWQC

    After a composite baseline BAF has been derived, the next step is 
to calculate a BAF that can be used for deriving AWQC for human health 
and wildlife. The data required to calculate a BAF are the composite 
baseline BAF, the fraction lipid of the aquatic species consumed by the 
population of interest whether that is humans or wildlife and the 
fraction of the chemical that is freely dissolved in the ambient water 
for the area of interest.

BAF for AWQC=[(baseline BAF)(fraction lipid of aquatic species 
consumed)+1](ffd)
1. Baseline BAF
    EPA is proposing to use the new, composite baseline BAFs derived 
above in section III.A: 53,080,000 for trophic level 4 and 26,735,000 
for trophic level 3.
2. Freely Dissolved Fraction
    The equation for estimating the freely dissolved fraction is 
presented above. EPA is proposing to use the composite log Kow of 
6.35 described above in section III.A. of this notice. EPA, however, is 
proposing to use the same values for POC and DOC used in the final rule 
(4.0 x 10-8 kg/L for POC and 2.0 x .10-6 kg/L for DOC). These values 
represent POC and DOC concentrations from Lake Superior and were used 
for all BAFs for AWQC in the final Guidance. Due to the change in the 
log Kow value, the freely dissolved value that EPA is today 
proposing to use is 0.6505.
3. Lipid Fraction
    EPA is not proposing any change to the lipid values used in the 
final

[[Page 54753]]

Guidance. The lipid fraction of the aquatic species consumed by humans 
in the Great Lakes region is 1.82 for trophic level 3 and 3.10 for 
trophic level 4 (60 FR 15404). For wildlife, the lipid fraction for 
trophic level 3 is 6.46 and for trophic level 4 is 10.31 (60 FR 15404).
4. Calculation
    Using the revised value for the freely dissolved fraction, EPA 
today proposes the following BAFs to be used in the human health and 
wildlife AWQCs for PCBs

Human Health BAF for trophic level 4=[(53,080,,000)(0.0310)+1] 
0.6505=1,070,000

Human Health BAF for trophic level 3=[(26,735,000)(0.0182)+1] 
0.6505=317,000

Wildlife BAF for trophic level 4=[(53,080,000)(0.1031)+1] 
0.6505=3,560,000

 Wildlife BAF for trophic level 3=[(26,735,000)(0.0646)+1] 
0.6505=1,123,000

IV. Human Health Cancer Criteria

    Based on the BAFs presented above, EPA today proposes to change the 
human health cancer criteria for PCBs in Table 3 of the final Guidance 
from 3.9E-6 ug/L to 6.8E-6 ug/L. EPA derived this revised value using 
the same equations used in the Great Lakes Water Quality Initiative 
Criteria Documents for the Protection of Human Health (EPA-820-B-95-
006). The only value EPA changed was the BAF value. The calculations 
are:
[GRAPHIC] [TIFF OMITTED] TP22OC96.010

Drinking Water Sources:
[GRAPHIC] [TIFF OMITTED] TP22OC96.013

Non-Drinking Water Sources:
[GRAPHIC] [TIFF OMITTED] TP22OC96.011

V. Wildlife Criteria

    For wildlife, EPA today proposes to change the PCB criteria from 
7.4E-5 ug/L to 1.2E-4 ug/L based on using the BAFs presented above. The 
equations and calculations of mammalian wildlife values are presented 
below. With the exception of the revised BAF values described above, 
the equations and data are identical to those used in the Great Lakes 
Water Quality Initiative Criteria Documents for Protection of Wildlife 
(EPA-820-B-95-008).

[[Page 54754]]

[GRAPHIC] [TIFF OMITTED] TP22OC96.012


    The geometric mean of these two mammalian wildlife values results 
in

WV (mammalian)=e([ln WV(mink)+ln WV(otter)]/2)
WV (mammalian)=e([ln 134.4 pg/L+ln 113.0 pg/L]/2)
WV (mammalian)=123 pg/L (two significant digits)=1.2 E-4 ug/L

VI. Request for Public Comment

    EPA is requesting comment on the approach for deriving a composite 
baseline BAF for PCBs and on the use of the composite Kow for PCBs 
used in estimating the fraction freely dissolved for PCBs. 
Specifically, EPA is requesting comment on whether using the total 
concentration of PCBs in tissue and the total concentration of PCBs in 
the ambient water to develop a composite baseline BAF for those 
congeners in Table 1 is preferable to the weighted geometric mean used 
in the final Guidance. EPA is also requesting comment on whether the 
composite Kow should be estimated using the median of the 
Kows for those congeners presented in Table 1. EPA also requests 
comments on the alternate method proposed for deriving the composite 
Kow. EPA also requests comments on whether it accurately computed 
the revised composite baseline BAF values, the revised composite 
Kow, the revised BAFs used for calculating the AWQC, and the 
revised human health and wildlife criteria. EPA is not requesting 
comment on the general methodology or the data used for deriving the 
baseline BAF. EPA is also not requesting information on the methodology 
or data used for deriving the BAF used in calculating AWQC. In 
addition, EPA is not requesting comment on the methodology or data 
(other than the BAFs) used to derive the human health cancer criteria 
or the wildlife criteria. These issues were fully addressed in the 
rulemaking for the final Guidance.

VII. Executive Order 12866

    Under Executive Order 12866 (58 FR 51735, October 4, 1993), EPA 
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 not a ``significant regulatory action'' 
and is therefore not subject to OMB review.

VIII. Regulatory Flexibility Act as Amended by the Small Business 
Regulatory Enforcement Fairness Act of 1996

    The Regulatory Flexibility Act (RFA) provides that, whenever an 
agency is required under 5 U.S.C. 553 to publish a general notice of 
rulemaking for any proposed rule, an agency must prepare an initial 
regulatory flexibility analysis unless the head of the agency certifies 
that the proposed rule will not have a significant economic impact on a 
substantial number of small entities. 5 U.S.C. 603 & 605. The purpose 
of the RFA is to establish procedures that ensure that Federal agencies 
solicit and consider alternatives to rules that would minimize their 
potential disproportionate impact on small entities.
    EPA has determined that the proposed rule, if promulgated, would 
not have a significant economic impact on a substantial number of small 
entities for the following reasons. As EPA has previously explained, 
until actions are taken to implement the final Guidance, there will be 
no economic effect of the final Guidance on any entities, large or 
small. States and Tribes must both adopt their own criteria and 
implement them before impacts are felt. The implementation regulations 
provide States and Tribes with a variety of flexible alternatives which 
can affect the burden felt by any small entity affected by this rule, 
including total maximum daily load (TMDL) calculations and waste load 
allocations (WLAs). Impacts

[[Page 54755]]

will not be felt until States and Tribes select and put in place 
implementation measures.
    Furthermore, today's proposal, if adopted, will result in human 
health cancer criteria and wildlife criteria less stringent than those 
currently in the final Guidance. If States or Tribes adopt criteria 
consistent with today's proposal, they will reduce any adverse economic 
impact that might have been imposed by State or Tribal adoption of the 
1995 criteria. Consequently, the economic effect of today's proposal 
relative to the 1995 Guidance should be positive. Any adverse economic 
impact on small entities associated with measures taken to implement 
the current provisions of the final Guidance should be reduced by 
adoption of the proposed revisions. For these reasons, the 
Administrator certifies, pursuant to section 605(b) of the RFA, that 
the proposed rule, if promulgated, will not have a significant economic 
impact on a substantial number of small entities.

IX. Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public 
Law 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 the 
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.
    As noted above, this rule is limited to the method for deriving a 
composite BAF for PCBs and for deriving a composite Kow for PCBs, 
which will result in human health cancer criteria and wildlife criteria 
for PCBs less stringent than those currently in the final Guidance. If 
States or Tribes adopt criteria consistent with today's proposal, they 
will reduce any adverse economic impact that might have been imposed by 
State or Tribal adoption of the 1995 criteria. Consequently, EPA has 
determined that this rule contains no regulatory requirements that 
might significantly or uniquely affect small governments. EPA has also 
determined that this rule does not contain a Federal mandate that may 
result in expenditures of $100 million or more for State, local, and 
Tribal governments, in the aggregate, or the private sector in any one 
year. Thus, today's rule is not subject to the requirements of sections 
202 and 205 of the UMRA.

X. Paperwork Reduction Act

    There are no information collection requirements in this proposed 
notice and therefore there is no need to obtain OMB approval under the 
Paperwork Reduction Act, 44 U.S.C. 3501 et seq.

XI. References

    Great Lakes Water Quality Technical Support Document for the 
Procedure to Determine Bioaccumulation Factors (EPA-820-B-95-005). 
NITS Number: PB95187290. ERIC Number: D049.
    Great Lakes Water Quality Initiative Criteria Documents for the 
Protection of Human Health (EPA-820-B-95-006). NITS Number: 
PB95187308. ERIC Number: D050.
    Great Lakes Water Quality Initiative Criteria Documents for 
Protection of Wildlife: DDT; Mercury; 2,3,7,8-TCDD; PCBs (EPA-820-B-
95-008). NITS Number: PB95187324. ERIC Number: D052.
    Hawker D.W. and D.W Connell. 1988. Octanol-Water Partition 
Coefficients of Polychlorinated Biphenyl Congeners. Environ. Sci. 
Technol., 22(4):382-387.
    Oliver, B.G. and A.J Niimi. 1988. Trophodynamic Analysis of 
Polychlorinated Biphenyl Congeners and Other Chlorinated 
Hydrocarbons in the Lake Ontario Ecosystem. Environ. Sci. Technol., 
22(4):388-397.
    U.S. Environmental Protection Agency. Water Quality Guidance for 
the Great Lakes System and Correction; Proposed Rules. Vol. 58, 
No.72. April 16, 1993. pp.20802-21047.
    U.S. Environmental Protection Agency. Water Quality Guidance for 
the Great Lakes System; Notice of Data Availability. Vol. 59. August 
30, 1994. pp.44678-44685.
    U.S. Environmental Protection Agency. Final Water Quality 
Guidance for the Great Lakes System; Final Rule. Vol. 60, No.56. 
March 23, 1995. pp.15366-15425.

List of Subjects in 40 CFR Part 132

    Environmental protection, Administrative practice and procedure, 
Great Lakes, Indians-lands, Intergovernmental relations, Reporting and 
recordkeeping requirements, Water pollution control.

    Dated: October 11, 1996.
Carol M. Browner,
Administrator.

    For the reasons set out in the preamble Title 40, Chapter I of the 
Code of Federal Regulations is proposed to be amended as follows:

PART 132--WATER QUALITY GUIDANCE FOR THE GREAT LAKES SYSTEM

    1. The authority citation for Part 132 continues to read as 
follows:

    Authority: 33 U.S.C. 1251 et seq.

    2. Table 3 to Part 132 is amended by revising the entry for 
PCBs(class) to read as follows:

                                             Table 3.--Water Quality Criteria for Protection of Human Health                                            
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             HNV (ug/L)                                                HCV (ug/L)                       
              Chemical               -------------------------------------------------------------------------------------------------------------------
                                                Drinking                   Nondrinking                    Drinking                   Nondrinking        
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                        
                   *                  *                  *                  *                  *                  *                  *                  
PCBs(class).........................  ...........................  ...........................  6.8E-6                       6.8E-6                     
                                                                                                                                                        
                   *                  *                  *                  *                  *                  *                  *                  
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 54756]]

    3. Table 4 to Part 132 is amended by revising the entry for 
PCBs(class) to read as follows:

       Table 4.--Water Quality Criteria for Protection of Wildlife      
------------------------------------------------------------------------
                  Chemical                         Criteria (ug/L)      
------------------------------------------------------------------------
                                                                        
                  *        *        *        *        *                 
PCBs(class)................................  1.2E-4                     
                                                                        
                  *        *        *        *        *                 
------------------------------------------------------------------------

[FR Doc. 96-26918 Filed 10-21-96; 8:45 am]
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