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Development of oil product toxicity benchmarks using SSDs
Citation:
Barron, M., CrystalR Jackson, AND M. Hemmer. Development of oil product toxicity benchmarks using SSDs. Presented at SETAC North America 33rd Annual Meeting, November 11 - 15, 2012.
Impact/Purpose:
Abstract for presentation at the November 2012 SETAC annual meeting in Longbeach, CA.
Description:
Determining the sensitivity of a diversity of species to spilled oil and chemically dispersed oil continues to be a significant challenge in spill response and impact assessment. We developed species sensitivity distributions (SSDs) of acute toxicity values using standardized tests from the literature for several petroleum products and two Corexit oil dispersants that had data for ten or more aquatic species. Fifth percentile hazard concentrations (HC5s) were computed from the SSDs and used to assess relative oil product toxicity and to determine the feasibility of establishing toxicity benchmarks for a community of species. The sensitivity of mysids (Americamysis bahia) and silversides (Menidia beryllina) were evaluated within the SSDs to determine if these common test species were good surrogates for a broader range of species. In general, SSD development was limited by the availability of acute toxicity values that met standardization criteria for a diversity of species. Because there was only small variability in the HC5s for the compiled oils, pooled SSDs were also developed by oil type (e.g., crude, middle distillate). There was only limited variability in HC5 values determined from dispersant-only testing for the two Corexit products. The relative sensitivity of mysids and silversides varied across the oil products, with the toxicity values always greater than the HC5. Application of SSDs appears to be a reasonable approach to developing oil product toxicity benchmarks, but additional toxicity data are needed for a larger range of species conducted under standardized test conditions.