[Federal Register Volume 59, Number 167 (Tuesday, August 30, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-21364]


[[Page Unknown]]

[Federal Register: August 30, 1994]


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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 122, 123, 131, and 132

[FRL-5061-4]
RIN 2040-AC08

 

Proposed Water Quality Guidance for the Great Lakes System

AGENCY: U.S. Environmental Protection Agency.

ACTION: Notice of data availability and request for comments.

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

SUMMARY: The purpose of this document is to announce the availability 
of three reports that EPA is considering as it develops the final Water 
Quality Guidance for the Great Lakes System (final Guidance) and to 
request public comment on the possible application of the data set 
forth in these reports in the final Guidance. The proposed Water 
Quality Guidance for the Great Lakes System (proposed Guidance) was 
published on April 16, 1993, in the Federal Register. Corrections to 
the proposed preamble and proposed rule text were published in the 
Federal Register on the same date and notices of additional reports and 
further corrections were published in the Federal Register on August 9, 
1993 and September 13, 1993.
    The three reports being made available for public comment today 
are: ``Results of Simulation Tests Concerning the Percent Dissolved 
Metal in Freshwater Toxicity Tests''; ``1991-1992 Michigan Sport 
Anglers Fish Consumption Study''; and ``Great Lakes Water Quality 
Initiative Technical Support Document for the Procedure to Determine 
Bioaccumulation Factors, July 1994.'' EPA wants to ensure that the 
public has an opportunity to comment on whether: the conversion factors 
for converting total recoverable metal criteria to dissolved metal 
criteria should be adopted in the final Guidance methodology for 
aquatic life; the fish consumption rates used in the development of 
human health criteria and values should be adjusted based on the 
results of the 1991-1992 Michigan Sport Anglers Fish Consumption Study; 
and the changes in the methodology for deriving Bioaccumulation Factors 
(BAFs) should be incorporated in the final Guidance.

DATES: Written comments should be submitted on or before September 29, 
1994. Comments postmarked after this date may not be considered.

ADDRESSES: Send written comments to Wendy Schumacher, Water Quality 
Branch (WQS-16J), U.S. EPA, Region V, 77 West Jackson Blvd., Chicago, 
Illinois, 60604 (telephone: 312-886-0142). Commenters are requested to 
submit one original and four copies of their written comments. A copy 
of the reports identified in this document are available for inspection 
and copying at the U.S. EPA Region V, 77 W. Jackson Blvd., Chicago, 
Illinois, by appointment only. Appointments may be made by calling 
Wendy Schumacher (telephone: 312-886-0142). A reasonable fee will be 
charged for photocopies. The three reports are also available by mail 
upon request for a fee by sending a written request to the above 
address.
    Alternatively, copies of the three reports may be obtained for a 
fee upon written request or telephone call to the Educational Resources 
Information Center/Clearinghouse for Science, Mathematics, and 
Environmental Education (ERIC/CSMEE), 1200 Chambers Road, Room 310, 
Columbus, Ohio 43212 (phone number: 614-292-6717). The report ``Great 
Lakes Water Quality Initiative Technical Support Document for the 
Procedure to Determine Bioaccumulation Factors, July 1994'' is also 
available for a fee upon written request or telephone call to the 
National Technical Information Center (NTIS), U.S. Department of 
Commerce, 5285 Port Royal Road, Springfield, VA 22161. The toll free 
number is 800-553-6847 and the local number is 703-487-4650. The NTIS 
Number is PB 94-202009.

FOR FURTHER INFORMATION CONTACT: Kenneth A. Fenner, Water Quality 
Branch Chief, (WQS-16J), U.S. EPA Region V, 77 W. Jackson Blvd., 
Chicago, Illinois, 60604 (telephone: 312-353-2079).

SUPPLEMENTARY INFORMATION: Section 304(a)(1) of the Clean Water Act (33 
U.S.C. 1314(a)(1)) requires EPA to publish and periodically update 
National ambient water quality criteria. These criteria are to reflect 
the latest scientific knowledge on the identifiable effects of 
pollutants on public health and welfare, aquatic life and recreation. 
Section 118(c)(2) of the Clean Water Act requires EPA to publish water 
quality guidance for the Great Lakes System which includes guidance on 
numerical limits on pollutants in ambient Great Lakes waters to protect 
human health, aquatic life and wildlife.
    The final Guidance will establish minimum water quality standards, 
antidegradation policies, and implementation procedures for waters 
within the Great Lakes System in the States of New York, Pennsylvania, 
Ohio, Indiana, Illinois, Minnesota, Wisconsin, and Michigan, including 
waters within the jurisdiction of Indian Tribes within the Great Lakes 
System.

A. Results of Simulation Tests Concerning the Percent Dissolved Metal 
in Freshwater Toxicity Tests

    In the toxicity tests used to develop EPA metals criteria for 
aquatic life, some fraction of the metal is dissolved while some 
fraction is precipitated or bound to particulate matter. It is 
generally believed that dissolved metals are more available for uptake 
by aquatic organisms than the bound or precipitated metal fractions and 
thus more likely to exert a toxic effect. The present National criteria 
to protect aquatic life were developed using total recoverable metal 
measurements or measures expected to give equivalent results in 
toxicity tests, and are expressed as total recoverable. In the past, 
States and Tribes have independently made the decision to express their 
metals criteria as either dissolved metal concentrations or total 
recoverable concentrations when applying the National aquatic life 
criteria.
    The acute and chronic aquatic life criteria presented in the 
proposed Guidance were expressed using total recoverable metal 
measurements, in conformance with the EPA policy at the time. In the 
preamble to the proposed Guidance, it was noted that a State or Tribe 
had flexibility when deriving criteria to choose either the total 
recoverable or dissolved contaminant concentrations. EPA suggested that 
a site-specific criteria modification procedure known as the water-
effects ratio could address concerns about the bioavailability and 
toxicity of total recoverable or dissolved concentrations. The preamble 
also indicated that EPA would promulgate total recoverable metals 
criteria for those States and Tribes who failed to adopt the criteria 
within the specified time period as written in the proposed Guidance.
    The EPA's Science Advisory Board (SAB) recommended in its December 
16, 1992, report, ``Evaluation of the Guidance for the Great Lakes 
Water Quality Initiative,'' that EPA consider both the biologically 
active form and the total contaminant concentrations of a pollutant 
when establishing water quality criteria (USEPA, 1992). To further 
elicit comment on the use of total recoverable vs. dissolved metal 
concentrations in developing future National aquatic life criteria, EPA 
held a meeting with invited experts in January 1993 in Annapolis, 
Maryland. The Agency solicited comments on the recommendations made by 
the presenters at the meeting in the Federal Register on July 9, 1993 
(58 FR 32131). Based on the data presented at the conference, and the 
individual opinions of the majority of assembled scientists, EPA 
determined that the dissolved metal concentration approximates the 
bioavailable fraction of waterborne metals for aquatic organisms better 
than the total recoverable concentration of metals. However, the 
scientists believed the total recoverable measurements in ambient water 
also have value, because exceedances of criteria on a total recoverable 
basis indicate that metal loadings could be a stress to the ecosystem, 
particularly in locations other than the water column. As a follow-up 
to the meeting, on October 1, 1993, EPA's Office of Water issued a 
memorandum to all EPA Regional Water Management Division Directors 
providing policy and guidance on the interpretation and implementation 
of aquatic life criteria for the management of metals (USEPA, 1993). 
The memorandum covered a number of areas including the expression of 
aquatic life criteria, total maximum daily loads, permits, effluent 
monitoring, compliance, and ambient monitoring. With regard to 
expression of aquatic life criteria, the memorandum recommended that 
State water quality standards be based on dissolved metals because 
dissolved metal concentrations more closely approximate the 
bioavailable fraction of metal in the water column than does total 
recoverable metal concentrations. However, because the present National 
aquatic life criteria were developed using total recoverable 
measurements, it is necessary to use a conversion factor to convert the 
total recoverable metal concentrations to equivalent dissolved metal 
concentrations. The October 1993 memorandum suggested conversion 
factors for 10 metals.
    Since that time, additional work has been completed to refine these 
conversion factors. Possible conversion factors for seven of the nine 
metals included in Tables 1 and 2 of the proposed Guidance for aquatic 
life are included in Table 1 of this Notice along with a conversion 
factor for lead. In addition, Table 1 includes preliminary conversion 
factors for cadmium and mercury(II). The basis for the cadmium and 
mercury(II) conversion factors can be found in the October 1993 
memorandum discussed above. Additional tests for cadmium and 
mercury(II) are being conducted as described in the report ``Results of 
Simulation Tests Concerning the Percent Dissolved Metal in Freshwater 
Toxicity Tests''. EPA does not at this time have any reason to believe 
that the final conversion factors for cadmium and mercury(II) will be 
different. EPA does not intend to provide additional opportunity to 
comment on the final conversion factors for cadmium and mercury(II).
    The methodology and data used to derive the nine conversion factors 
can be found in the report ``Results of Simulation Tests Concerning the 
Percent Dissolved Metal in Freshwater Toxicity Tests,'' which is 
available in the public docket as described in the addresses section of 
this notice. To use these factors, a State or Tribe would multiply the 
criterion for a metal in Table 1 or 2 of the proposed Guidance by the 
conversion factor in Table 1 of this notice. For example, if the acute 
water quality criterion for chromium(III) based on total recoverable 
metal concentration is 15 ug/L and the conversion factor is 0.333, then 
the equivalent dissolved metal concentration for chromium(III) would be 
5.0 ug/L.
    If EPA were to publish the final Guidance with metals criteria 
expressed as dissolved concentrations, States and Tribes would be 
required to adopt metals criteria consistent with the final Guidance. 
In that situation, a State or Tribe could adopt criteria expressed as 
dissolved criteria, or they could choose to adopt the total recoverable 
criteria without using conversion factors as in the proposed Guidance, 
since it is a more stringent approach. If a State or Tribe did not 
adopt metals criteria consistent with the final Guidance, EPA would 
promulgate dissolved metals criteria for that State or Tribe. This 
approach is consistent with the recommendations made by the Science 
Advisory Board and the scientists who attended the January 1993 meeting 
in Annapolis, Maryland.
    EPA requests comment on the information in the report, ``Results of 
Simulation Tests Concerning the Percent Dissolved Metal in Freshwater 
Toxicity Tests,'' including: (1) the conversion factors in Table 1 of 
this notice (and in Table 22 of the report) and the adequacy of the 
data supporting the conversion factors; (2) the procedure used to 
derive the conversion factors; and (3) any additional data that could 
be used in developing the conversion factors. 

      Table 1.--Recommended Conversion Factors for Converting Total     
         Recoverable Metal Criteria to Dissolved Metal Criteria         
------------------------------------------------------------------------
                                                  Conversion  Conversion
                                                  factor for  factor for
                     Metal                           acute      chronic 
                                                   criteria    criteria 
------------------------------------------------------------------------
Arsenic(III)....................................      1.000       1.000 
Cadmium\1\......................................       .850        .850 
Chromium(III)...................................       .333        .860 
Chromium(VI)....................................       .988        .966 
Copper..........................................       .958        .958 
Lead............................................       .875        .792 
Mercury(II)\1\..................................       .850        .850 
Nickel..........................................       .998        .997 
Selenium(IV)....................................       .922        .922 
Zinc............................................       .981       .992  
------------------------------------------------------------------------
\1\Preliminary conversion factors--factors (and relevant data) found in 
  October 1993 EPA memorandum. Recommended conversion factors are given 
  to three decimal places and are not rounded off because they are      
  intermediate values in the calculation of dissolved criteria.         

B. 1991-1992 Michigan Sport Anglers Fish Consumption Study

    The rate of fish consumption is an aspect of exposure used in the 
methodology for deriving human health criteria. The current fish 
consumption rate used in the derivation of National ambient water 
quality criteria is 6.5 grams/day, which represents a National average 
consumption value per person for freshwater and estuarine fish and 
shellfish. The proposed Guidance included a fish consumption rate of 15 
grams/day, which represents the mean exposure level for regionally 
caught fish for the regional sportfishing population. This estimate was 
made from a review of several regional studies in Michigan, Wisconsin 
and New York.
    A study conducted by West et al., ``1991-1992 Michigan Sport 
Anglers Fish Consumption Study,'' for the State of Michigan was 
submitted during the public comment period for the proposed Guidance. 
The study had three main objectives: (1) to determine fish consumption 
patterns that could then be used in setting water quality standards in 
Michigan; (2) to determine angler compliance with Michigan fish 
consumption advisories and patterns of preparing fish recommended in 
fish consumption advisories; and (3) to determine which sub-populations 
are at greatest risk so that educational programs about fish 
consumption advisories can be targeted to those populations.
    The survey was conducted over one year and included 7000 licensed 
Michigan anglers who were sampled by mail. A systematic random sample 
was drawn such that stratification by geographic region and license 
type within each region was used to ensure that each licensed angler 
had the same chance of being selected. By ordering the population by 
license type within a region, a proportionate State-wide distribution 
of anglers was achieved. Questionnaires were mailed in two-week cohorts 
throughout the study period of January 30, 1991 through January 29, 
1992. Surveyed individuals were asked to report detailed fish 
consumption patterns over the preceding 7 days. The survey reported a 
response rate of about 47%.
    The authors of the report include seven options that represented 
their opinions on the possible policy choices available to the State of 
Michigan. The seven policy options include:
    Option 1--6.5 grams/day. This represents the average consumption 
level for the State of Michigan as a whole (not just sportanglers).
    Option 2--14.5 grams/day. This represents the average sport fish 
consumption level by Michigan sport fishermen, adjusted for non-
response bias.
    Option 3--24.3 grams/day. This represents the average total fish 
consumption level by Michigan sport fishermen, adjusted for non-
response bias.
    Option 4--30 grams/day. This represents the 80th percentile sport 
fish consumption by Michigan sport fishermen.
    Option 5--40.8 grams/day. This represents the 80th percentile of 
total fish consumption by Michigan sport fishermen.
    Option 6--43.1 grams/day. This represents the average sport fish 
consumption level for the highest consuming sport fish sub-group (lower 
income minorities).
    Option 7--57.9 grams/day. This represents the average total fish 
consumption level for the highest consuming sport fish sub-group (low 
income minorities). The West study also documents individual 
consumption rates in excess of this value.
    The policy options presented in the survey do not necessarily 
reflect the opinions of the State of Michigan, but EPA believes that 
they are included in the range of possible fish consumption rates that 
could be used as part of the final Guidance methodology for deriving 
human health criteria.
    EPA requests comments on the, ``1991-1992 Michigan Sport Anglers 
Fish Consumption Study'' including: (1) The appropriateness of the 
study methods used in study; (2) the seven policy options in Chapter 6 
of the report on possible fish consumption rates for Michigan; (3) the 
applicability of the results in the study to other parts of the Great 
Lakes Basin; and (4) the appropriateness of using a fish consumption 
rate for the final Guidance higher than the proposed 15 grams/day, 
based on the range of values considered in the West et al., study or 
other relevant and appropriate data, and alternative approaches to 
address different levels of fish consumption in a waterbody.

C. Great Lakes Water Quality Initiative Technical Support Document for 
the Procedure to Determine Bioaccumulation Factors, July 1994 
(Technical Support Document, July 1994)

    As explained in the preamble for the proposed Guidance, aquatic 
organisms accumulate chemicals in their tissues from exposure to 
chemicals from all sources, including food and water. Further, as 
organisms at lower trophic levels are consumed by organisms at higher 
trophic levels, tissue concentrations of some chemicals increase. As a 
result of biomagnification, chemical levels in top predators may be 
orders of magnitude higher than concentrations of the chemical in the 
ambient water. In the development of National water quality criteria, 
EPA used the term ``bioconcentration factors (BCF)'' to reflect the 
propensity of an organism to accumulate a chemical in its tissues. When 
field-measured bioaccumulation factors (BAFs) were not available, BCFs 
were used as estimates of BAFs. In the proposed Guidance, EPA requested 
comment on two uses of BAFs, which account for exposure from all 
sources.
    First, EPA calculated BAFs for individual chemicals at different 
trophic levels. The BAFs at the appropriate trophic level consumed by 
humans and wildlife species were then used to derive human health and 
wildlife criteria. In general, if all other factors were equal, a 
chemical with a higher bioaccumulation factor would have a lower (more 
stringent) criterion. Second, EPA used the human health BAFs to 
identify a list of ``bioaccumulative chemicals of concern'' which 
warrant increased attention in the Great Lakes Basin. See Section II.G. 
(at 58 FR 20843) of the preamble to the proposed Guidance (58 FR 
20802).
    EPA is today soliciting comment on additional technical information 
about BAFs and alternative options to approaching four issues described 
in the proposed Guidance. EPA is also soliciting comment on the newly 
calculated BAFs for the chemicals in Tables 3 and 4 of the proposed 
Guidance for human health and wildlife species based on the information 
and options discussed in this Notice. These BAFs, if promulgated, would 
change the criteria for human health and wildlife in Tables 3 and 4 of 
the proposed Guidance.
    The proposed Guidance included a hierarchy of three methods for 
deriving BAFs for organic chemicals: a field- measured BAF; a BAF 
predicted by multiplying a BCF measured in the laboratory by a food 
chain multiplier (FCM); and a BAF predicted from a BCF calculated from 
the chemical's n- octanol/water partition coefficient (Kow) and 
multiplied by a FCM. For inorganic chemicals, EPA proposed to require 
either a field-measured BAF or BCF. The four issues discussed in this 
Notice all pertain to the derivation of BAFs for organic chemicals.
    EPA is considering whether it should revise its proposed 
methodology for the calculation of BAFs in the Great Lakes System to 
incorporate the information discussed in the Technical Support 
Document, 1994, and summarized below. The material discussed in 
sections C.1, C.2, and C.3 would replace portions of the proposed 
Guidance. The material discussed in section C.4 would provide a new 
method for deriving a BAF for organic chemicals and this method would 
be added to the hierarchy of methods for organics described above.
    As explained in the proposed Guidance, EPA proposes to require 
States and Tribes to adopt requirements for calculation of BAFs that 
are consistent with EPA's final methodology. Although the State or 
Tribal regulation need not duplicate this methodology, the State's or 
Tribe's method must produce a BAF at least as stringent as the BAFs 
derived by using EPA's methodology. If EPA incorporates the topics 
discussed in the Technical Support Document, 1994, and this Notice into 
its methodology, States and Tribes will be required to reflect them in 
their methodologies and derivation of BAFs. EPA also notes that, if EPA 
incorporates the material discussed in sections C.1 to C.4 into its 
methodology for deriving a BAF, EPA would use this material in 
promulgating BAFs for any State or Tribe.
    The bioaccumulation concepts contained in this Notice, the 
references supporting these concepts, and additional details are 
discussed in the Technical Support Document, July 1994, which is 
available in the public docket for this Notice.

1. Use of Freely Dissolved Concentration of Chemical in Derivation of 
BAFs

    In the proposed Guidance, human health and wildlife bioaccumulation 
factors for organic chemicals were based on the total concentration of 
the chemical in water. For highly lipophilic chemicals, however, a 
substantial percentage of the total concentration can be associated 
with particulate organic carbon (POC) and dissolved organic carbon 
(DOC) in water and be unavailable for accumulation. BAFs, whether 
measured or predicted, can be derived using the concentration of the 
chemical that is freely dissolved in the water in order to account for 
bioavailability. EPA requested comment on the concept of basing the 
bioaccumulation factors for lipophilic organic chemicals on the freely 
dissolved concentration instead of the total concentration, but did not 
provide a specific equation for deriving the freely dissolved 
concentration.
    In this Notice, EPA is requesting comment on an equation included 
in the Technical Support Document, July 1994, which defines the 
relationship of a BAF reported on the basis of the total concentration 
of the chemical in the water to a BAF reported on the basis of the 
freely dissolved concentration of the chemical in the water. The freely 
dissolved concentration is defined by the following equation:

BAFlt=ffd  BAFlfd    (1)

where
BAFlt=BAF (L/Kg of lipid) reported on the basis of the lipid-
normalized concentration of chemical in the biota (Kg/Kg lipid) divided 
by the total concentration of the chemical in the water (Kg/L);
BAFlfd=BAF (L/Kg of lipid) reported on the basis of the 
lipid-normalized concentration of chemical in the biota (Kg/Kg lipid) 
divided by the freely dissolved concentration of the chemical in the 
water (Kg/L); and
ffd=fraction of the total chemical that is freely dissolved in the 
water.

    The fraction of the chemical that is freely dissolved in the water, 
ffd, can be determined using equation 2 with the Kow for the 
chemical and the concentration of DOC and POC in the water.

ffd=1/{1+(POCKow)+(DOC
    Kow/10)}(2)

where
POC=concentration of particulate organic carbon, Kg of organic carbon/L 
of water;
DOC=concentration of dissolved organic carbon, Kg of organic carbon/L 
of water; and
Kow=n-octanol/water partition coefficient.

For further details on the derivation of this equation, including 
possible default values for POC and DOC, see the Technical Support 
Document, July 1994, which is available in the public docket for this 
Notice.
    Basing the measured and predicted BAFs on the concentration of the 
freely dissolved chemical in water permits the derivation of BAFs that 
take into account site-specific concentrations of POC and DOC. This 
approach would also allow consistent usage and derivation of BAFs 
through out the Guidance if a model similar to the model for predicting 
FCMs (see section C.3 of this Notice) and the procedure for predicting 
BCFs (see section C.2 of this Notice) were used because both are based 
upon the concentration of the freely dissolved chemical in the water. 
EPA requests comments on the application and validity of the equation 
for deriving the freely dissolved concentration.

2. Use of the Equation Log BCF = Log Kow

    In the proposed Guidance, the third method for deriving a BAF for 
organic chemicals involved predicting a BCF from a chemical's n-
octanol/water partition coefficient by the equation (Veith and Kosian, 
1983):

log BCF=0.79 log Kow - 0.40  (3)

    EPA asked for comment on other ways to predict a BCF from a log 
Kow.
    In this Notice, EPA is requesting comment on use of an alternate 
equation to predict BCFs, included in the Technical Support Document, 
July 1994, using the following approximation:

BCFlfd  Kow  (4)

where the BCFlfd is the BCF reported on a lipid-normalized 
basis using the freely dissolved concentration of the chemical in the 
water. This relationship is applicable to lipophilic non-polar organic 
chemicals which have log Kows greater than 3 and which are either 
slowly or never metabolized by aquatic organisms. A similar equation 
can be developed for chemicals with log Kow less than 3 which 
incorporates the partitioning of the chemical to the aqueous phase. For 
a more detailed explanation, see Appendix C of the Technical Support 
Document, July 1994.
    Equation 4 implicitly assumes that n-octanol is an appropriate 
surrogate for lipids in aquatic organisms. The theoretical basis 
presented by Mackay (1982) and the experimental data suggest that n-
octanol is a very reasonable surrogate for lipids. Equation 4 is also 
supported and consistent with the food-chain model of Gobas (1993). For 
the Gobas model, the BCFtfd is equal to Kow when the 
growth rate of the organisms and the metabolism rate of the chemical by 
the organisms are set equal to zero. Finally, equation 4 is supported 
and consistent with the equilibrium partitioning theory being developed 
by EPA for the derivation of sediment quality criteria (Di Toro et al. 
1991).
    EPA believes that predicting the BCF based on equation 4 may 
provide a more consistent and scientifically defensible basis for 
establishing a predicted BAF than the equation by Veith and Kosian, 
1983. EPA asks for comments on the use of equation 4 for predicting 
BCFs.

3. Food Chain Multiplier Model

    The second and third methods in the proposed Guidance for deriving 
BAFs for organic chemicals both require use of a FCM based on a 
biomagnification model by Thomann (1989). For the proposed Guidance, 
EPA calculated the FCMs using Thomann's 1989 model of the step-wise 
increase in the concentration of an organic chemical from phytoplankton 
(trophic level 1) through the top predatory fish of a food chain 
(trophic level 4). Food chain multipliers derived from the model ranged 
from less than one to 100. Under the proposed Guidance, FCMs greater 
than one would usually apply to organic chemicals with log Kow 
values in the range of 4.0 to 6.5. EPA asked for comment on the 
appropriateness of FCMs based on the Thomann model, and requested 
possible alternatives to the Thomann model for predicting BAFs from 
BCFs.
    In this Notice, EPA requests comment on the use of a model by Gobas 
(1993) to determine FCMs for non-polar organic chemicals. This model 
includes both benthic and pelagic food chains thereby incorporating 
exposures of organisms to chemicals from both the sediment and the 
water column. The Thomann 1989 model included only the pelagic food 
chain and therefore did not account for exposure from sediment to the 
aquatic organisms. The model by Gobas (1993) predicts a) the chemical 
residues in the organisms, and b) the freely dissolved concentration of 
the chemical in the water column (Cfd). With this information, 
bioaccumulation factors for each species in the food chain can be 
predicted by the equation:

BAFlt=Residue in aquatic organism / Cwdf    (5)

FCM's can then be calculated from the predicted BAFs using the 
following equation:

FCM=BAFlfd / Kow    (6)

where Kow is the n-octanol/water partition coefficient for the 
chemical and BAFlfd is the BAF reported on a lipid- 
normalized basis using the freely dissolved concentration of the 
chemical in water.
    Since EPA is considering using the following approximation to 
predict BCFs:

FCFlfd=Kow    (7)


substituting equation (7) into equation (6) would give a relationship 
for calculating FCMs similar to the proposed Guidance where

FCM=BAFlfd/BCFlfd.    (8)

    The resulting FCMs for trophic levels 2, 3, and 4 along with the 
input parameters for the model, are included in the Technical Support 
Document, July 1994. Based on the data in the TSD, EPA believes the 
Gobas model acceptably predicts BAFs for the Great Lakes System.
    EPA is considering using the food chain model of Gobas for deriving 
FCMs because a) it is easier to define the input data needed to run the 
model, b) predicted BAFs are in better agreement with measured BAFs for 
chemicals with very high log Kows, and c) the model uses 
equilibrium partitioning theory to predict chemical residues in benthic 
organisms, consistent with EPA's sediment criteria approach.
    EPA is requesting comment on the appropriateness of the Gobas 1993 
model for calculating FCMs.

4. Biota-Sediment Accumulation Factors

    As explained above, the proposed Guidance presented a hierarchy of 
three methods to derive BAFs for non-polar organic chemicals. In this 
Notice, EPA requests comment on modifying the proposed Guidance's 
hierarchy by adding a predicted BAF based on a biota-sediment 
accumulation factor (BSAF) as the second method in the hierarchy. The 
revised hierarchy would reflect this modification as follows:

1. A BAF measured in the field;
2. A BAF predicted from a field-measured BSAF, methodology discussed 
below;
3. A BAF predicted by multiplying a BCF measured in the laboratory by 
the food chain multiplier; and
4. A BAF predicted by multiplying a BCF calculated from the log 
Kow by the food chain multiplier.

    BSAFs may be used for measuring and predicting bioaccumulation 
directly from concentrations of chemicals in surface sediment. They may 
also be used to estimate BAFs (Cook et al., 1993; 1994). Since BSAFs 
are based on field data and incorporate effects of metabolism, 
biomagnification, growth, etc., BAFs estimated from BSAFs will 
incorporate the net effect of all these factors. The BSAF approach is 
particularly beneficial for developing water quality criteria for 
chemicals such as polychlorinated dibenzo-p-dioxins (PCDDs) and 
polychlorinated dibenzofurans (PCDFs) and certain biphenyl congeners 
which are detectable in fish tissues and sediments but are difficult to 
measure in the water column and have reduced bioaccumulation potential 
due to metabolism.
    BSAFs are measured by relating lipid-normalized concentrations of 
chemicals in an organism to organic carbon-normalized concentrations of 
the chemicals in surface sediment samples associated with the average 
exposure environment of the organism. The BSAF is defined as:

where
BSAF = Cl / Csoc    (9)

Cl = the lipid-normalized concentration of the chemical in tissues 
of the biota (g/g lipid).
Csoc = the organic carbon-normalized concentration of the chemical 
in the surface sediment (g/g sediment organic carbon).

    Differences between BSAFs for different organic chemicals are good 
measures of the relative bioaccumulation potentials of the chemicals. 
When calculated from a common organism/sediment sample set, chemical-
specific differences in BSAFs primarily reflect the net effect of 
biomagnification, metabolism, and bioenergetics and bioavailability 
factors on each chemical's disequilibrium ratio between biota and 
sediment.
    In the proposed Guidance, ratios of BSAFs of PCDDs and PCDFs to a 
BSAF for 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) were 
proposed for evaluation of 2,3,7,8-TCDD toxic equivalency associated 
with complex mixtures of these chemicals (bioaccumulation equivalency 
factors, see 58 FR 20802). The same approach is applicable to 
calculation of BAFs for other organic chemicals. The approach requires 
data for a steady-state or near steady-state condition between sediment 
and water for both a reference chemical (r) with a measured BAF and 
other chemicals (n=i) for which BAFs are to be determined. BAFd for a 
chemical ``i'' is defined as:

(BAlfd)i = [(BAFDlfd)r  [(BSAF)i 
(Kow)i) / (BSAF)r (Kow)r]    (10)

BAFs calculated from two different BSAF data sets for Lake Ontario 
salmonids are similar and agree well with measured BAFs of Oliver and 
Niimi (1988). For further details on predicting BAFs from BSAF 
measurements, and the data supporting this approach, see the Technical 
Support Document, July 1994. EPA is requesting comment on the inclusion 
of the BAF predicted from a BSAF in the preferred order of data.

5. Bioaccumulation Equivalency Factors

    The preamble to the proposed Guidance included a list of the 
Bioaccumulation Equivalency Factors (BEFs) for PCDDs and PCDFs that 
could be used when converting concentrations of PCDDs and PCDFs to 
equivalent concentrations of 2,3,7,8- TCDD. These BEFs have been 
updated since the proposal and are included in Table 2. The technical 
rationale for the revised BEFs is provided in the Technical Support 
Document, July 1994. EPA requests comment on the revised BEFs.

             Table 2.--Bioaccumulation Equivalency Factors              
------------------------------------------------------------------------
                          Congener                             TCDD BEF 
------------------------------------------------------------------------
2,3,7,8-TCDD.................................................     1.0   
1,2,3,7,8-PeCDD..............................................     0.92  
1,2,3,4,7,8-HxCDD............................................     0.3   
1,2,3,6,7,8-HxCDD............................................     0.12  
1,2,3,7,8,9-HxCDD............................................     0.14  
1,2,3,4,6,7,8-HpCDD..........................................     0.051 
OCDD.........................................................     0.0013
2,3,7,8-TCDF.................................................     0.80  
1,2,3,7,8-PeCDF..............................................     0.22  
2,3,4,7,8-PeCDF..............................................     1.6   
1,2,3,4,7,8-HxCDD............................................     0.076 
1,2,3,6,7,8-HxCDF............................................     0.19  
2,3,4,6,7,8-HxCDF............................................     0.67  
1,2,3,7,8,9-HxCDD............................................     0.63  
1,2,3,4,6,7,8-HpCDF..........................................     0.011 
1,2,3,4,7,8,9-HpCDF..........................................     0.39  
OCDF.........................................................     0.016 
------------------------------------------------------------------------

6. Comparison of Proposed BAFs and Potential Final BAFs for Human 
Health and Wildlife Criteria

    Bioaccumulation factors for the 20 human health and 4 wildlife 
criteria in Tables 3 and 4 of the proposed Guidance have been 
recalculated incorporating the modifications to the BAF methodology 
discussed above. The BAFs for these chemicals are compared with the 
proposed BAFs in Tables 3 and 4 of this Notice. In addition, if the 
changes under consideration in this Notice are incorporated into the 
final Guidance, the BAF for 1,2,4-Trichlorobenzene would increase from 
836 to 1,570. This is significant because 1,2,4-Trichlorobenzene could 
then be classified as a Bioaccumulative Chemical of Concern (BCC), 
chemicals with BAFs greater than 1000, which could require special 
provisions for control as discussed in the proposed Guidance.
    As in the proposed Guidance, the human health BAFs are calculated 
using trophic level 4 and assuming a lipid content in fish of 5 
percent. The wildlife BAFs are calculated using trophic level 3 or 4 as 
appropriate for the wildlife species and assuming a lipid content in 
fish of 7.9 percent. The derivation of the BAFs for the 20 human health 
criteria, the 4 wildlife criteria, and 1,2,4- Trichlorobenzene are 
included in the Technical Support Document for Bioaccumulation Factors, 
July 1994.
    EPA requests comments on: (1) The BAFs derived using the 
modifications to the BAF methodology; and (2) the addition of 1,2,4-
trichlorobenzene to the list of BCCs.

            Table 3--Human Health Bioaccumulation Factors\1\            
------------------------------------------------------------------------
                                        Proposed     Todays    Method\2\
               Chemical                 guidance     notice             
------------------------------------------------------------------------
Benzene..............................          13           8          4
Chlordane............................     219,375     250,000          1
Chlorobenzene........................          49          38          4
Cyanide..............................           0           0        N/A
4,4-DDT..............................   1,913,875   1,550,000          1
Dieldrin.............................      28,171     997,000          2
2,4-Dimethylphenol...................         156         157          3
2,4-Dinitrophenol....................         4.8           3          4
Heptachlor...........................      19,097      57,900          3
Hexachlorobenzene....................     208,590     111,000          1
Hexachloroethane.....................         950         947          1
Lindane..............................       1,628       4,260          1
Mercury..............................     130,440     140,000          3
Methylene chloride...................         2.5           2          4
PCBs.................................   1,776,860     435,000          1
Pentachlorophenol....................         650         627          3
2,3,7,8-TCDD.........................      50,000     101,000          2
Toluene..............................       1,547       1,550          3
Toxaphene............................   2,117,450   2,120,000          1
1,2,4-Trichlorobenzene...............         836       1,570          1
Trichloroethylene....................          18          18         3 
------------------------------------------------------------------------
\1\The BAFs are based on 5% lipid and on the concentration of total     
  chemical in the water.                                                
\2\BAF Methods:                                                         
1. A BAF measured in the field;                                         
2. A BAF predicted from a field-measured BSAF;                          
3. A BAF predicted by multiplying a laboratory measured BCF by the food 
  chain multiplier; and                                                 
4. A BAF predicted by multiplying a BCF calculated from the log Kow by  
  the food chain multiplier.                                            


                                  Table 4--Wildlife Bioaccumulation Factors\1\                                  
----------------------------------------------------------------------------------------------------------------
                                                 Trophic level 3               Trophic level 4                  
                                       -------------------------------------------------------------            
               Chemical                   Proposed                           Proposed      Todays     Method\2\ 
                                          guidance      Todays notice        guidance     notice                
----------------------------------------------------------------------------------------------------------------
4,4'-DDT..............................    1,043,966             2,170,000    3,023,922    4,040,000            1
Mercury...............................       60,542                27,900      130,440      140,000            3
PCBs..................................      969,239               658,000    2,807,439      687,000            1
2,3,7,8-TCDD..........................       79,000               320,000       79,000      160,000           2 
----------------------------------------------------------------------------------------------------------------
\1\The BAFs are based on 7.9% lipid and on the concentration of total chemical in the water.                    
\2\BAF Methods:                                                                                                 
1. A BAF measured in the field;                                                                                 
2. A BAF predicted from a field-measured BSAF;                                                                  
3. A BAF predicted by multiplying a laboratory measured BCF by the food chain multiplier; and                   
4. A BAF predicted by multiplying a BCF calculated from the log Kow by the food chain multiplier.               

7. Literature Cited

Cook, P.M., R.J. Erickson, R.L. Spehar, S.P. Bradbury, and G.T. 
Ankley. 1993. Interim report on data and methods for assessment of 
2,3,7,8-tetrachlorodibenzo-p-dioxin risks to aquatic life and 
associated wildlife. EPA/600/R-93/055. U.S. Environmental Protection 
Agency, Environmental Research Laboratory, Duluth MN, March 1993.
Cook, P.M., G.T. Ankley, R.J. Erickson, B.C. Butterworth, S.W. 
Kohlbry, P. Marquis and H. Corcoran. 1994. The biota-sediment 
accumulation factor (BSAF): evaluation and application to assessment 
of organic chemical bioaccumulation in the Great Lakes. In 
preparation.
Di Toro, D.M., C.S. Zarba, D.J. Hansen, W.J. Berry, R.C. Swartz, 
C.E. Cowan, S.P. Pavlou, H.E. Allen, N.A. Thomas, and P.R. Paquin. 
1991. Technical basis for establishing sediment quality criteria for 
nonionic organic chemicals using equilibrium partitioning. Environ. 
Toxicol. Chem., 10, 1541-1583.
Federal Register, Vol. 58, No. 72. Water Quality Guidance for the 
Great Lakes System and Correction; Proposed Rules. April 16, 1993 
(58 FR 20802).
Federal Register, Vol. 58, No. 72. Water Quality Guidance for the 
Great Lakes System; Correction. April 16, 1993 (58 FR 21046).
Federal Register, Vol. 58, No. 108. Water Quality Criteria: Aquatic 
Life Criteria for Metals; Notice of Availability with Request for 
Comments. June 8, 1993 (58 FR 32131).
Federal Register, Vol. 58, No. 151. Water Quality Guidance for the 
Great Lakes System; Proposed Rules; Availability of Documents, 
correction. August 9, 1993 (58 FR 42266).
Federal Register, Vol. 58, No. 175. Water Quality Guidance for the 
Great Lakes System; Proposed Rule; Availability of Documents; 
Extension of Comment Period. September 13, 1993 (58 FR 47845).
Gobas, F.A.P.C. 1993. A model for predicting the bioaccumulation of 
hydrophobic organic chemicals in aquatic food-webs: application to 
Lake Ontario. Ecological Modelling, 69, 1-17.
Mackay, D. 1982. Correlation of bioconcentration factors. Environ. 
Sci. Technol., 16, 274-278.
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: 388-397.
Thomann, R.V. 1989. Bioaccumulation Model of Organic Chemical 
Distribution in Aquatic Food Chains. Environ. Sci. Technol. 23:699-
707.
U.S. EPA. 1992. An SAB report: Evaluation of the Guidance for the 
Great Lakes Water Quality Initiative, Science Advisory Board. U.S. 
EPA, Washington, D.C., EPA-SAB-EPEC/DWC-93-005.
U.S. EPA. 1993. Memorandum concerning Office of Water Policy and 
Technical Guidance on Interpretation and Implementation of Aquatic 
Life Metals Criteria. October 1, 1993.
U.S. EPA. 1994. Great Lakes Water Quality Initiative Technical 
Support Document for the Procedure to Determine Bioaccumulation 
Factors, July 1994. EPA-822-R-94-002 U.S. EPA, Office of Science and 
Technology, Washington, D.C.
U.S. EPA. 1994. Draft Results of Simulation Tests Concerning the 
Percent Dissolved Metal in Freshwater Toxicity Tests.
Veith, G.D., and P. Kosian. 1983. Estimating Bioconcentration 
Potential from Octanol/Water Partition Coefficients. Chapter 15 in 
PCBs in the Great Lakes. Mackay, D., R. Patterson, S. Eisenreich, 
and M. Simmons (eds.). Ann Arbor Science.
West, P, M. Fly, R. Marans, F. Larkin, and D. Rosenblatt. 1993. 
1991-1992 Michigan Sport Anglers Fish Consumption Study. Final 
Report to the Michigan Great Lakes Protection Fund, Michigan Dept. 
of Natural Resources. University of Michigan, School of Natural 
Resources, Natural Resource Sociology Research Lab. Technical Report 
#6. May 1993.

    Dated: August 23, 1994.
Robert Perciasepe,
Assistant Administrator.
[FR Doc. 94-21364 Filed 8-29-94; 8:45 am]
BILLING CODE 6560-50-P