You are here:
PROCEDURES FOR DERIVING EQUILIBRIUM PARTITIONING SEDIMENT BENCHMARKS (ESBS) FOR THE PROTECTION OF BENTHIC ORGANISMS: DIELDRIN
Citation:
Berry, W J., R M. Burgess, D Hansen, D. M. Di Toro, L. D. De Rosa, H. E. Bell, M. C. Reiley, F E. Stancil, C S. Zarba, D. R. Mount, AND R L. Spehar. PROCEDURES FOR DERIVING EQUILIBRIUM PARTITIONING SEDIMENT BENCHMARKS (ESBS) FOR THE PROTECTION OF BENTHIC ORGANISMS: DIELDRIN. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-02/010, 2003.
Impact/Purpose:
This report will be useful for the program offices, including Superfund, and Regions in conducting contaminated sediment assessments. The document represents approximately 15 years of research by scientists in ORD working with the Office of Water, and a review of the scientific approach was conducted by EPA's Science Advisory Board. The document is being published to aid in the conduct of sediment assessments.
Description:
This equilibrium partitioning sediment benchmark (ESB) document describes procedures to derive concentrations of the insecticide dieldrin in sediment which are protective of the presence of benthic organisms. The equilibrium partitioning (EqP) approach was chosen because it accounts for the varying biological availability of chemicals in different sediments and allows for the incorporation of the appropriate biological effects concentration. This provides for the derivation of benchmarks that are causally linked to the specific chemical, applicable across sediments, and appropriately protective of benthic organisms.
EqP can be used to calculate ESBs for any toxicity endpoint for which there are water-only toxicity data; it is not limited to any single effect endpoint. For the purposes of this document, the Final Chronic Value (FCV) from the Water Quality Criterion (WQC) for dieldrin was used as the toxicity benchmark. This value is intended to be the concentration of a chemical in water that is protective of the presence of aquatic life. The ESBWQC is derived by multiplying the FCV by the chemical's KOC, yielding the concentration in sediment (normalized to organic carbon) that should provide the same level of protection in sediment that the FCV provides in water. For dieldrin, this concentration is 12 mg dieldrin/gOC for freshwater sediments and 28 mg/gOC for saltwater sediments. Confidence limits of 5.4 to 27 mg/gOC for freshwater sediments and 12 to 62 mg/gOC for saltwater sediments were calculated using the uncertainty associated with the degree to which toxicity could be predicted by multiplying the KOC and the water-only effects concentration. The ESBWQCs should be interpreted as chemical concentrations below which adverse effects are not expected. At concentrations above the ESBWQCs, effects may occur with increasing severity as the degree of exceedance increases.
The ESBs do not consider the antagonistic, additive or synergistic effects of other sediment contaminants in combination with dieldrin or the potential for bioaccumulation and trophic transfer of dieldrin to aquatic life, wildlife or humans.