Developing Ecological Soil Screening Level (Eco-SSL) Benchmarks for Ba, Be, Mn, and Sb Toxicities to Soil Invertebrates. R. T. Checkai, R. G. Kuperman, M. Simini, C. T. Phillips, J. A. Speicher, and D. G. Barclift; US Army Edgewood Chemical Biological Center, Aberdeen Proving Ground, MD, Geo-Centers, Inc., US Navy Engineering Field Activity Northeast
The U.S. Environmental Protection Agency (USEPA) is developing Ecological Soil Screening Level (Eco-SSL) benchmarks for ecological risk assessment (ERA) of contaminants at Superfund sites. The Eco-SSL derivation process represents the collaborative effort of a multi-stakeholder workgroup consisting of USEPA, DoD, DOE, State, private industry, and academic participants. Eco-SSLs are ecotoxicity values that can be used routinely in screening ERAs to identify those contaminants in soil that warrant additional evaluation in a baseline ERA, and to eliminate those that do not. Eco-SSLs are developed from literature values whenever sufficient quantity and quality of data exist. Insufficient data were available on the toxicity of Ba, Be, Mn, and Sb to soil invertebrates, necessitating toxicity testing. Tests were conducted under conditions preferred for Eco-SSL derivation, using a Sassafras sandy loam soil that supports relatively high bioavailability of Ba, Be, Mn, and Sb. Metals in soil were aged/weathered to better reflect contaminant exposure at Superfund sites. Bioassays used include enchytraeid reproduction (ISO/16387:2001) measuring juvenile production by the potworm Enchytraeus crypticus, earthworm cocoon production (ISO/11268-2:1998) by Eisenia fetida, and collembola reproduction (ISO/11267:1998) measuring juvenile production by Folsomia candida. These tests measured the toxicity of soil contaminants to ecologically relevant test species during chronic assay of reproductive measurement endpoints. EC20 values (mg kg-1, for potworm/earthworm/collembola) were Ba (630/390/15), Be (41/51/22), Mn (50/358/399), Sb (194/30/81). Draft-benchmarks (mg kg-1) based on these data are Ba (154), Be (36), Mn (193), and Sb (78). Results will undergo quality assurance by Eco-SSL task group before inclusion in the Eco-SSL database.
Research sponsored by U.S. Navy Engineering Field Activity Northeast, and U.S. Environmental Protection Agency.
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