TLi=Bioaccumulation factor (BAF) for wildlife food
in trophic level i in liters per kilogram (L/kg), developed using the BAF
methodology in appendix B to part 132, Methodology for Development of
Bioaccumulation Factors. For consumption of piscivorous birds by other birds
(e.g., herring gull by eagles), the BAF is derived by multiplying the trophic
level 3 BAF for fish by a biomagnification factor to account for the
biomagnification from fish to the consumed birds.
B. Identification of Representative Species for Protection. For
bioaccumulative chemicals, piscivorous species are identified as the focus of
concern for wildlife criteria development in the Great Lakes. An analysis of
known or estimated exposure components for avian and mammalian wildlife species
is presented in the Wildlife TSD. This analysis identifies three avian species
(eagle, kingfisher and herring gull) and two mammalian species (mink and otter)
as representative species for protection. The TD obtained from toxicity data for
each taxonomic class is used to calculate WVs for each of the five
representative species.
C. Calculation of Avian and Mammalian Wildlife Values and GLWC
Derivation. The avian WV is the geometric mean of the WVs calculated for the
three representative avian species. The mammalian WV is the geometric mean of
the WVs calculated for the two representative mammalian species. The lower of
the mammalian and avian WVs must be selected as the GLWC.
III. PARAMETERS OF THE EFFECT COMPONENT OF THE WILDLIFE CRITERIA METHODOLOGY
A. Definitions. The following definitions provide additional
specificity and guidance in the evaluation of toxicity data and the application
of this methodology.
Acceptable endpoints. For the purpose of wildlife criteria derivation,
acceptable subchronic and chronic endpoints are those which affect reproductive
or developmental success, organismal viability or growth, or any other endpoint
which is, or is directly related to, parameters that influence population
dynamics.
Chronic effect. An adverse effect that is measured by assessing an
acceptable endpoint, and results from continual exposure over several
generations, or at least over a significant part of the test species' projected
life span or life stage.
Lowest-observed-adverse-effect-level (LOAEL). The lowest tested dose
or concentration of a substance which resulted in an observed adverse effect in
exposed test organisms when all higher doses or concentrations resulted in the
same or more severe effects.
No-observed-adverse-effect-level (NOAEL). The highest tested dose or
concentration of a substance which resulted in no observed adverse effect in
exposed test organisms where higher doses or concentrations resulted in an
adverse effect.
Subchronic effect. An adverse effect, measured by assessing an
acceptable endpoint, resulting from continual exposure for a period of time less
than that deemed necessary for a chronic test.
B. Minimum Toxicity Database for Tier I Criteria Development. A TD
value is required for criterion calculation. To derive a Tier I criterion for
wildlife, the data set shall provide enough data to generate a subchronic or
chronic dose-response curve for any given substance for both mammalian and avian
species. In reviewing the toxicity data available which meet the minimum data
requirements for each taxonomic class, the following order of preference shall
be applied to select the appropriate TD to be used for calculation of individual
WVs. Data from peer-reviewed field studies of wildlife species take precedence
over other types of studies, where such studies are of adequate quality. An
acceptable field study must be of subchronic or chronic duration, provide a
defensible, chemical-specific dose-response curve in which cause and effect are
clearly established, and assess acceptable endpoints as defined in this
document. When acceptable wildlife field studies are not available, or
determined to be of inadequate quality, the needed toxicity information may come
from peer-reviewed laboratory studies. When laboratory studies are used,
preference shall be given to laboratory studies with wildlife species over
traditional laboratory animals to reduce uncertainties in making interspecies
extrapolations. All available laboratory data and field studies shall be
reviewed to corroborate the final GLWC, to assess the reasonableness of the
toxicity value used, and to assess the appropriateness of any UFs which are
applied. When evaluating the studies from which a test dose is derived in
general, the following requirements must be met:
1. The mammalian data must come from at least one well-conducted study of 90
days or greater designed to observe subchronic or chronic effects as defined in
this document.
2. The avian data must come from at least one well-conducted study of 70 days
or greater designed to observe subchronic or chronic effects as defined in this
document.
3. In reviewing the studies from which a TD is derived for use in calculating
a WV, studies involving exposure routes other than oral may be considered only
when an equivalent oral daily dose can be estimated and technically justified
because the criteria calculations are based on an oral route of exposure.
4. In assessing the studies which meet the minimum data requirements,
preference should be given to studies which assess effects on developmental or
reproductive endpoints because, in general, these are more important endpoints
in ensuring that a population's productivity is maintained. The Wildlife TSD
provides additional discussion on the selection of an appropriate toxicity
study.
C. Selection of TD Data. In selecting data to be used in the
derivation of WVs, the evaluation of acceptable endpoints, as defined in Section
III.A of this appendix, will be the primary selection criterion. All data not
part of the selected subset may be used to assess the reasonableness of the
toxicity value and the appropriateness of the Ufs which are applied.
1. If more than one TD value is available within a taxonomic class, based on
different endpoints of toxicity, that TD, which is likely to reflect best
potential impacts to wildlife populations through resultant changes in mortality
or fecundity rates, shall be used for the calculation of WVs.
2. If more than one TD is available within a taxonomic class, based on the
same endpoint of toxicity, the TD from the most sensitive species shall be used.
3. If more than one TD based on the same endpoint of toxicity is available
for a given species, the TD for that species shall be calculated using the
geometric mean of those TDs.
D. Exposure Assumptions in the Determination of the TD. 1. In those
cases in which a TD is available in units other than milligrams of substance per
kilograms per day (mg/kg/d), the following procedures shall be used to convert
the TD to the appropriate units prior to calculating a WV.
2. If the TD is given in milligrams of toxicant per liter of water consumed
by the test animals (mg/L), the TD shall be multiplied by the daily average
volume of water consumed by the test animals in liters per day (L/d) and divided
by the average weight of the test animals in kilograms (kg).
3. If the TD is given in milligrams of toxicant per kilogram of food consumed
by the test animals (mg/kg), the TD shall be multiplied by the average amount of
food in kilograms consumed daily by the test animals (kg/d) and divided by the
average weight of the test animals in kilograms (kg).
E. Drinking and Feeding Rates. 1. When drinking and feeding rates and
body weight are needed to express the TD in milligrams of substance per
kilograms per day (mg/kg/d), they are obtained from the study from which the TD
was derived. If not already determined, body weight, and drinking and feeding
rates are to be converted to a wet weight basis.
2. If the study does not provide the needed values, the values shall be
determined from appropriate scientific literature. For studies done with
domestic laboratory animals, either the Registry of Toxic Effects of Chemical
Substances (National Institute for Occupational Safety and Health, the latest
edition, Cincinnati, OH), or Recommendations for and Documentation of Biological
Values for Use in Risk Assessment (U.S. EPA, 1988) should be consulted. When
these references do not contain exposure information for the species used in a
given study, either the allometric equations from Calder and Braun (1983) and
Nagy (1987), which are presented below, or the exposure estimation methods
presented in Chapter 4 of the Wildlife Exposure Factors Handbook (U.S. EPA,
1993), should be applied to approximate the needed feeding or drinking rates.
Additional discussion and recommendations are provided in the Wildlife TSD. The
choice of the methods described above is at the discretion of the State or
Tribe.
3. For mammalian species, the general allometric equations are:
a. F = 0.0687 × (Wt)0.82
Where:
F = Feeding rate of mammalian species in kilograms per day (kg/d) dry weight.
Wt = Average weight in kilograms (kg) of the test animals.
b. W = 0.099 × (Wt)0.90
Where:
W = Drinking rate of mammalian species in liters per day (L/d).
Wt = Average weight in kilograms (kg) of the test animals.
4. For avian species, the general allometric equations are:
a. F = 0.0582 (Wt)0.65
Where:
F = Feeding rate of avian species in kilograms per day (kg/d) dry weight.
Wt = Average weight in kilograms (kg) of the test animals.
b. W = 0.059 × (Wt)0.67
Where:
W = Drinking rate of avian species in liters per day (L/d).
Wt = Average weight in kilograms (kg) of the test animals.
F. LOAEL to NOAEL Extrapolations (UFL). In those cases in
which a NOAEL is unavailable as the TD and a LOAEL is available, the LOAEL may
be used to estimate the NOAEL. If used, the LOAEL shall be divided by an UF to
estimate a NOAEL for use in deriving WVs. The value of the UF shall not be less
than one and should not exceed 10, depending on the dose-response curve and any
other available data, and is represented by UFL in the equation
expressed in Section II.A of this appendix. Guidance for selecting an
appropriate UFL, based on a review of available wildlife toxicity
data, is available in the Wildlife TSD.
G. Subchronic to Chronic Extrapolations (USS). In instances
where only subchronic data are available, the TD may be derived from subchronic
data. In such cases, the TD shall be divided by an UF to extrapolate from
subchronic to chronic levels. The value of the UF shall not be less than one and
should not exceed 10, and is represented by UFS in the equation
expressed in Section II.A of this appendix. This factor is to be used when
assessing highly bioaccumulative substances where toxicokinetic considerations
suggest that a bioassay of limited length underestimates chronic effects.
Guidance for selecting an appropriate UFS, based on a review of
available wildlife toxicity data, is available in the Wildlife TSD.
H. Interspecies Extrapolations (UFA). 1. The
selection of the UFA shall be based on the available toxicological
data and on available data concerning the physicochemical, toxicokinetic, and
toxicodynamic properties of the substance in question and the amount and quality
of available data. This value is an UF that is intended to account for
differences in toxicological sensitivity among species. Guidance for selecting
an appropriate UFA, based on a review of available wildlife toxicity
data, is available in the Wildlife TSD. Additional discussion of an interspecies
UF located in appendix A to the Great Lakes Water Quality Initiative Technical
Support Document for Human Health Criteria may be useful in determining the
appropriate value for UFA.
2. For the derivation of Tier I criteria, a UFA shall not be less
than one and should not exceed 100, and shall be applied to each of the five
representative species, based on existing data and best professional judgment.
The value of UFA may differ for each of the representative species.
3. For Tier I wildlife criteria, the UFA shall be used only for
extrapolating toxicity data across species within a taxonomic class, except as
provided below. The Tier I UFA is not intended for interclass
extrapolations because of the poorly defined comparative toxicokinetic and
toxicodynamic parameters between mammals and birds. However, an interclass
extrapolation employing a UFA may be used for a given chemical if it
can be supported by a validated biologically-based dose-response model or by an
analysis of interclass toxicological data, considering acceptable endpoints, for
a chemical analog that acts under the same mode of toxic action.
IV. PARAMETERS OF THE EXPOSURE COMPONENT OF THE WILDLIFE CRITERIA
METHODOLOGY
A. Drinking and Feeding Rates of Representative Species. The body
weights (Wt), feeding rates (FTli), drinking rates (W), and trophic
level dietary composition (as food ingestion rate and percent in diet) for each
of the five representative species are presented in Table D-2 of this appendix.
Guidance on incorporating the non-aquatic portion of the bald eagle and mink
diets in the criteria calculations is available in the Wildlife TSD.
B. BAFs. The Methodology for Development of Bioaccumulation Factors is
presented in appendix B to part 132. Trophic level 3 and 4 BAFs are used to
derive Wvs because these are the trophic levels at which the representative
species feed.
V. REFERENCES
A. Barnes, D.G. and M. Dourson. 1988. Reference Dose (RfD): Description and
Use in Health Risk Assessments. Regul. Toxicol. Pharmacol. 8:471-486.
B. Calder III, W.A. and E.J. Braun. 1983. Scaling of Osmotic Regulation in
Mammals and Birds. American Journal of Physiology. 244:601-606.
C. Nagy, K.A. 1987. Field Metabolic Rate and Food Requirement Scaling in
Mammals and Birds. Ecological Monographs. 57(2):111-128.
D. National Academy of Sciences. 1977. Chemical Contaminants: Safety and Risk
Assessment, in Drinking Water and Health, Volume 1. National Academy
Press.
E. National Academy of Sciences. 1980. Problems of Risk Estimation, in
Drinking Water and Health, Volume 3. National Academy Press.
F. National Institute for Occupational Safety and Health. Latest edition.
Registry of Toxic Effects of Chemical Substances. Division of Standards
Development and Technology Transfer. (Available only on microfiche or as an
electronic database.)
G. U.S. EPA. 1980. Appendix C. Guidelines and Methodology Used in the
Preparation of Health Effect Assessment Chapters of the Consent Decree Water
Criteria Documents, pp. 79347-79357 in Water Quality Criteria Documents;
Availability. Available from U.S. Environmental Protection Agency, Office of
Water Resource Center (WH-550A), 1200 Pennsylvania Ave., NW, Washington, DC
20460.
H. U.S. EPA. 1988. Recommendations for, and documentation of, biological
values for use in risk assessment. NTIS-PB88-179874.
I. U.S. EPA. 1993. Wildlife Exposure Factors Handbook, Volumes I and II.
EPA/600/R-93/187a and b.
Tables to Appendix D to Part 132 Table D-1_Tier I Great Lakes Wildlife Criteria
------------------------------------------------------------------------
Substance Criterion (mg/L)
------------------------------------------------------------------------
DDT & Metabolites....................... 1.1E-5
Mercury..................................... 1.3E-3
PCBs (total)................................ 7.4E-5
2,3,7,8-TCDD................................ 3.1E-9
------------------------------------------------------------------------
Table D-2_Exposure Parameters for the Five Representative Species Identified for Protection
----------------------------------------------------------------------------------------------------------------
Water
Adult body ingestion Food ingestion rate of Trophic level of prey
Species (units) weight rate (L/ prey in each trophic (percent of diet)
(kg) day) level (kg/day)
----------------------------------------------------------------------------------------------------------------
Mink................................. 0.80 0.081 TL3: 0.159; Other: TL3: 90; Other: 10.
0.0177.
Otter................................ 7.4 0.600 TL3: 0.977; TL4: 0.244. TL3: 80; TL4: 20.
Kingfisher........................... 0.15 0.017 TL3: 0.0672............ TL3: 100.
Herring gull......................... 1.1 0.063 TL3: 0.192; TL4: 0.0480 Fish: 90_TL3: 80; TL4:
20.
.......... ........... Other: 0.0267.......... Other: 10.
Bald eagle........................... 4.6 0.160 TL3: 0.371; TL4: 0.0929 Fish: 92_TL3: 80; TL4:
20.
.......... ........... PB: 00283; Other: Birds: 8_PB: 70; non-
0.0121. aquatic: 30.
----------------------------------------------------------------------------------------------------------------
Note: TL3=trophic level three fish; TL4=trophic level four fish; PB=piscivorous birds; Other=non-aquatic birds
and mammals.
