Dames & Moore, 1999 - USDA Forest Service
Dames & Moore, 1999 - USDA Forest Service Dames & Moore, 1999 - USDA Forest Service
Concentrations of PCOCs in other media, such as vegetation, aquatic insects. earthworms, and small mammals, were accounted for by modeling. In summary, the exposure pathways that are potentially complete at these sites and that will be quantitatively considered in this ERA are: Surface water to benthic organisms and fish Sediment to benthic organisms and fish Soil to terrestrial vegetation Soil to other terrestrial receptors Vegetation to terrestrial herbivores and omnivores Terrestrial and aquatic biota to upper trophic level consumers 7.2.2.4 Sentinel, Indicator, and Surrogate Species - The Guild Approach Receptor guilds (organisms with similar life histories or niches in the environment) have been used rather than individual species for.this assessment because the general characteristics of each guild will provide risk estimates that are representative of the entire guild. As such, these can be extrapolated more broadly than single species estimates. The underlying concept is that each receptor of particular concern falls into a group of potential receptors that function in similar ecological niches ("guilds"). For example, many species of hawk feed on small mammals and require trees or cliffs for roosts. As such, each of these hawks display similar life-histories and would be anticipated to have similar exposures to PCOCs at the sites. A single surrogate, for example the red-tailed hawk, for which good life-history information, or toxicological data is available, may be used for modeling purposes and results may be extrapolated to the "mammal-eating hawk guild" as a whole. This allows the risk assessment models to directly evaluate species for which the best exposure information is available, but allows results to be extrapolated to a broader range of potential receptors, thereby maximizing data usage and applicability of results. Representatives in each identified receptor guild and trophic level are selected below. The fundamental assumption is that if the surrogate receptor is protected, the entire guild is protected. Deviations from this assumption are discussed further in the uncertainty section of this report. 7.2.2.5 Selection of ROCs: Guild Representatives The broadest classifications of receptors selected for this ERA are aquatic and terrestrial plants and animals. Of the animals, fish, mammals, and birds are the three most prominent general groups at the site. Fish, using salrnonids as representative species, were selected as an ROC because they are an important valued resource and because they may provide food for certain birds and mammals, as well as recreation for humans. Benthic insects were also selected as ROCs because they are important food items for fish and some birds. Although periphyton is an important component of aquatic food chains, there are only a few reports of the effects of metals on these communities. Therefore, this trophic level will only be discussed briefly and qualitatively. Although amphibians may exist at the site, and may be at risk from metals contamination, there is very little toxicological data for these animals. The available mean toxicity data for amphibians exposed to cadmium, & MOORE c : \ ~ ~ ) ~ \ h 0 1 d r n - ~ ~ ~ 7 ~ . d o ~ 17693-005-019Uuly 27.1999,5:16 PM;DRAFT FlNAL RI REPORT 7-44 DAMES
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. G:\wrpdauU~OJkponrUIoIdm-2\ri\7O.doc 7-45 17693-005419Uuly 27.1999.5:16 P W M FINAL RI REPORT
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Concentrations of PCOCs in other media, such as vegetation, aquatic insects.<br />
earthworms, and small mammals, were accounted for by modeling.<br />
In summary, the exposure pathways that are potentially complete at these sites and that will be<br />
quantitatively considered in this ERA are:<br />
Surface water to benthic organisms and fish<br />
Sediment to benthic organisms and fish<br />
Soil to terrestrial vegetation<br />
Soil to other terrestrial receptors<br />
Vegetation to terrestrial herbivores and omnivores<br />
Terrestrial and aquatic biota to upper trophic level consumers<br />
7.2.2.4 Sentinel, Indicator, and Surrogate Species - The Guild Approach<br />
Receptor guilds (organisms with similar life histories or niches in the environment) have been used rather<br />
than individual species for.this assessment because the general characteristics of each guild will provide risk<br />
estimates that are representative of the entire guild. As such, these can be extrapolated more broadly than<br />
single species estimates. The underlying concept is that each receptor of particular concern falls into a<br />
group of potential receptors that function in similar ecological niches ("guilds"). For example, many species<br />
of hawk feed on small mammals and require trees or cliffs for roosts. As such, each of these hawks display<br />
similar life-histories and would be anticipated to have similar exposures to PCOCs at the sites. A single<br />
surrogate, for example the red-tailed hawk, for which good life-history information, or toxicological data is<br />
available, may be used for modeling purposes and results may be extrapolated to the "mammal-eating hawk<br />
guild" as a whole. This allows the risk assessment models to directly evaluate species for which the best<br />
exposure information is available, but allows results to be extrapolated to a broader range of potential<br />
receptors, thereby maximizing data usage and applicability of results.<br />
Representatives in each identified receptor guild and trophic level are selected below. The fundamental<br />
assumption is that if the surrogate receptor is protected, the entire guild is protected. Deviations from this<br />
assumption are discussed further in the uncertainty section of this report.<br />
7.2.2.5 Selection of ROCs: Guild Representatives<br />
The broadest classifications of receptors selected for this ERA are aquatic and terrestrial plants and animals.<br />
Of the animals, fish, mammals, and birds are the three most prominent general groups at the site. Fish,<br />
using salrnonids as representative species, were selected as an ROC because they are an important valued<br />
resource and because they may provide food for certain birds and mammals, as well as recreation for<br />
humans. Benthic insects were also selected as ROCs because they are important food items for fish and<br />
some birds. Although periphyton is an important component of aquatic food chains, there are only a few<br />
reports of the effects of metals on these communities. Therefore, this trophic level will only be discussed<br />
briefly and qualitatively.<br />
Although amphibians may exist at the site, and may be at risk from metals contamination, there is very little<br />
toxicological data for these animals. The available mean toxicity data for amphibians exposed to cadmium,<br />
& MOORE<br />
c : \ ~ ~ ) ~ \ h 0 1 d r n - ~ ~ ~ 7 ~ . d o ~<br />
17693-005-019Uuly 27.<strong>1999</strong>,5:16 PM;DRAFT FlNAL RI REPORT<br />
7-44 DAMES