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Protectiveness of Species Sensitivity Distribution Hazard Concentrations for Acute Toxicity Used in Endangered Species Risk Assessment
Citation:
RAIMONDO, S., D. VIVIAN, C. DELOS, AND M. G. BARRON. Protectiveness of Species Sensitivity Distribution Hazard Concentrations for Acute Toxicity Used in Endangered Species Risk Assessment. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 27(12):2599-2607, (2008).
Impact/Purpose:
Research demonstrates the protectiveness of Species Sensitivity Distributions (SSDs) in endangered species risk assessment using an extensive dataset of acute toxicity and proposes two potential methods that may reduce uncertainty in SSDs used for protection of species of concern.
Description:
A primary objective of threatened and endangered species conservation is to ensure that chemical contaminants and other stressors do not adversely affect listed species. Assessments of the ecological risks of chemical exposures to listed species often rely on the use of surrogate species, safety factors, and Species Sensitivity Distributions (SSDs) of chemical toxicity; however, the protectiveness of these approaches is uncertain. We comprehensively evaluated the protectiveness of SSD 1st and 5th percentile hazard concentrations (HC1, HC5) relative to the application of safety factors using 68 SSDs generated from 1479 acute (LC50) toxicity records for 291 species, including 24 endangered species (20 fish, 4 mussels). SSD HC5s and HC1s were less than 98 and 100% of all endangered species mean acute LC50s, respectively. HC5s were significantly lower than the concentrations derived from applying safety factors of 5 and 10 to rainbow trout (Oncorhynchus mykiss) toxicity data and HC1s were generally less than the concentrations derived from a safety factor of 100 applied to rainbow trout toxicity values. Comparison of relative sensitivity (SSD percentiles) of broad taxonomic groups found that crustaceans were generally the most sensitive taxa and taxa sensitivity was related to chemical mechanism of action. Comparison of relative sensitivity of narrow fish taxonomic groups showed standard test fish species were generally less sensitive than salmonids and listed fish. We recommend the use of SSDs as a community-level risk assessment approach that is generally protective of listed species.