PARENT SESSION

WA6 Fate and Effects of Energetic Compounds
202 Oregon Ballroom
8:00 AM - 12:00 PM, Wednesday

() Toxicity of the new nitramine energetic material CL-20 to soil and aquatic ecological receptors.

Kuperman, R.¹, Checkai, R.¹, Simini, M.¹, Phillips, C.¹, Haley, M.¹, Anthony, J.¹, Kolakowski, J.¹, Kurnas, C.¹, Davis, E.¹, ¹ U.S. Army Edgewood Chemical Biological Center, Aberdeen Proving Ground, MD, USA

ABSTRACT- We investigated the toxicity of the new energetic material CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, -polymorph) to both soil and aquatic ecological receptors. We adapted standardized soil and aquatic bioassays to investigate CL-20 toxicity. We determined toxicological benchmarks based on concentration-response relationships for the soil invertebrates earthworm Eisenia fetida (ISO 11268-2:1998), potworm Enchytraeus crypticus (ISO/16387:2001), and collembolan Folsomia candida (ISO 11267:1998); terrestrial plants alfalfa Medicago sativa, Japanese millet Echinochloa crusgalli, and perennial ryegrass Lolium perenne (USEPA and ASTM); and the aquatic species water flea Ceriodaphnia dubia, fathead minnow Pimephales promelas, and green algae Selenastrum capricornutum (USEPA). Measurement endpoints were assessed using multiple treatment concentrations and appropriate controls. We measured CL-20 in soil by extracting with acetonitrile, and in aqueous media by adding acetonitrile, then determining the respective CL-20 concentrations using a modified USEPA Method 8330. We then correlated CL-20 concentrations in the resepctive media with reproduction or growth endpoints using nonlinear regression models to determine the corresponding EC₂₀ and EC₅₀ values. Soil invertebrate and plant bioassays were conducted under experimental conditions preferred for establishing toxicological benchmarks for deriving an Ecological Soil Screening Level (Eco-SSL; USEPA 2003), using a Sassafras sandy loam (SSL) soil that supports relatively high bioavailability of CL-20. Toxicity in soil was individually assessed for CL-20 freshly amended in SSL folowing a 24-h equilibration period of hydrated soil, and for CL-20 weathered and aged in SSL for 20 weeks. Aquatic toxicity bioassays were performed using test media directly amended with CL-20 to simulate direct release into surface waters, and elutriates from SSL amended with CL-20 in order to simulate contamination of surface waters from soil surface runoff. Toxicity benchmarks developed in these studies will be made available for use in Ecological Risk Assessment should terrestrial or aquatic habitats become contaminated with CL-20 through its introduction into the environment and concomitant ecosystem exposure.

Key words: toxicity, CL-20, terrestrial receptors , aquatic organisms