PT02 Soil Toxicology and Risk Assessment
Exhibit Hall
8:00 AM - Tuesday, 11 November 2003
(PT027) Toxicity of a new energetic material CL-20 to Folsomia candida in a natural soil.
Phillips, C, Checkai, R, Kuperman, R, Simini, M, Anthony, J, Kolakowski, J, Kurnas, C,
ABSTRACT- Hexanitrohexaazaisowurtzitane (CL-20) is a new energetic material, a polycyclic nitramine compound similar to the explosives HMX and RDX, but with a larger caged structure and greater energetic efficiency. We are investigating the effects of CL-20 on the soil invertebrate Folsomia candida (Collembola) using a Folsomia Reproduction Test (ISO 11267:1998) to determine adult survival and juvenile production. We selected this test based on its ability to measure chemical toxicity to an ecologically relevant test species, and its inclusion of reproduction as a measurement endpoint. Bioassays were conducted using Sassafras sandy loam soil that supports relatively high bioavailability of CL-20. Bioassays were done using soil freshly amended with CL-20. Measurement endpoints were assessed using 7-9 treatment concentrations including negative, carrier (acetone), and positive controls, with five replicates per treatment. Data for juvenile production were analyzed using nonlinear regression models, including ECp parameters to determine the CL-20 concentration producing a specified percentage effect. These parameters included EC50 and EC20 levels. Results gave bounded NOEC and LOEC values for adult survival of 0.9 and 1.1 mg/kg, respectively; and EC50 and EC20 values of 0.7 and 0.2 mg/kg for the reproduction endpoint, respectively, based on measured concentrations of CL-20 in soil. These results for reproduction indicate that CL-20 is more toxic than either HMX or RDX to F. candida. Ongoing testing of weathered/aged CL-20 amended soil will provide information on the potential alterations in CL-20 ecotoxicity in contaminated field sites.
Key words: Folsomia candida, explosive CL20, ecotoxicity, juvenile production