Dames & Moore, 1999 - USDA Forest Service

copper, lead, and zinc is shown in Table 7.2.2-3. With the exception of one series of tests with one species
of amphibian (Gasterophyene carqlinensk) tested, all other available data shows amphibians to be less
sensitive than salmonid fishes (Table 7.2.3-1B). This one amphibian species is native to Kentucky and is
not found in Washington. When this species was exposed to mercury at different dates in the same
laboratory, much higher (1,300 times) LC5Os were obtained (Table 7.2.2-3), and even this higher LC50 was
lower than was found for 13 ,other species, and 16.6 times lower than the mean of all species tested (Table
7.2.2-3). Thus, this species and series.of tests are not representative of the majority of amphibians toxicity
test results. Therefore, amphibians were considered to be protected by the toxicity reference values used
for salmonids and amphibians were not selected as an ROC.
Terrestrial plants were also selected as ROCs because of their major role in primary production. their role
of providing food for herbivores, and their scenic and economic value to humans. Likewise. earthworms
have been selected to represent terrestrial invertebrates because of their role in nutrient cycling and
providing food to birds and mammals.
Mammals and birds were selected as ROCs. Mammals and birds are further subdivided into carnivores
(piscivores, invertevores), herbivores, and omnivores. Life history and related information (e.g., Terres,
1982; Palmer and Fowler, 1975; USEPA, 1993) was reviewed to identify surrogates for these receptor
guilds for which sufficient ecological and toxicological information exists to perform a quantitative
assessment of risk. In keeping with species observed on site and the guild approach discussed above, a list
of ROCs was selected for the quantification of risk at the Holden Mine aquatic and terrestrial habitats. The
resultant list of receptor guild surrogates is shown in Table 7.2.2-4. These species or guilds were selected
for risk characterization in the following sections because 1) they are most likely to be present and because
2) there is an adequate toxicological database to support the analysis.
Sources of Toxicity Data
Risks to trout and benthic invertebrates were estimated using "Toxicological Benchmah for Screening
Potential Contaminants of Concem for Eflects on Aquatic Biota" (Suter and Tsao, 1996). Grasses and forbs
exist on the soils and mine tailings areas and toxicity to such plants can be estimated using the data
presented in "Toxicological Benchmarks for Screening Contaminants of Potential Concem for Eflects on
Terresfrial Plants" (Efroymson et al., 1997). Essential ecological data for estimating risk to birds and
mammals are available in "Toxicological Benchmarks for Wildlife 'I (Sample et al., 1996), "Methou3 and
Tools for Estimation of the Exposure of Terresrrial Wildlife to Contaminants" (Sample et al., 1997), and
"Wildlije Exposure Factors Handbook" (USEPA, 1993). By using the plant uptake factors in Efroymson et
al. (1997), it is possible to estimate risk to herbivores such as the mule deer, and deer mouse. Similarly, by
using uptake factors in "Development and Validation of Bioaccumulation Models for Emhworms" (Sample
et al., 1997b) and 'LDevelopment and Validation of Bioaccumulaion Models for Small Mammals" (Sample
et al., 1998), it was possible to estimate the doses and risk to shrews, mink, and red-tailed hawk. Estimating
risk to American dipper and little brown bat involved simple modeling of body burdens in aquatic insects.
Measured body burdens in trout were used to estimate doses to mink and osprey. At each trophic level. these
benchmark documents were supplemented with original, peer-reviewed literature and field study results to
account for site-specific differences.
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FINAL RI REPORT