Sensitivity of ecological soil-screening levels for metals to exposure model parameterization and toxicity reference values.
Bottom Line: Soil ingestion ranked 2nd for carnivores and herbivores, but was 4th for invertivores.The approach for TRV selection was also examined in detail, with Cu as the representative analyte.The underlying assumption that generic body-weight-normalized TRVs can be used to derive protective levels for any species is not supported by the data.
Affiliation: Ecological Risk, Rancho Murieta, California, USA.Show MeSH
Related in: MedlinePlus
Mentions: To better understand the basis for the interactions observed for the bioaccumulation parameter, earthworm, plant, and small mammal Eco-SSL bioaccumulation models (presented in Supplemental Data Tables, S4–S6) were implemented for all analytes over the range of Eco-SSL soil concentrations for the 6 receptor species (Figure 2). These figures display how estimated tissue concentrations vary with soil concentration under each model. Patterns of mean ranks of estimated soil concentrations for trophic groups (Figure 1) generally correspond to the relative rates of bioaccumulation for their respective food types (Figure 2). Low bioaccumulation rates corresponded with lower importance of the FIR and bioaccumulation, and greater importance of Ps. In contrast, Ps was less important, and FIR and bioaccumulation were more important, when bioaccumulation rates were high. For example, the amount of bioaccumulation of Co into earthworms and small mammals greatly exceeds that observed for plant tissues. Similarly, the bioaccumulation into earthworms of Cu, Pb, and V to a lesser degree greatly exceeds that for plants and small mammals, indicating that bioaccumulation for these metals is of greater importance for invertivores than for either herbivores or carnivores. In contrast, Zn bioaccumulation into small mammal tissue as a function of soil concentration is essentially flat and much less than that for either earthworms or plants. The extreme soil concentration estimates for Zn in carnivores when soil ingestion is zero are a consequence of this shallow slope. Elevated (but not statistically significant) importance of the soil ingestion parameter associated with low bioaccumulation rates into small mammals (Figure 2) is also evident for As, Ba, Be, and Cd (Supplemental Data, Figures S2–S5).
Affiliation: Ecological Risk, Rancho Murieta, California, USA.