T8 AM Ecological Fate and Effects of Explosives and Related Compounds
Tuesday, 15 November 2005: 8:00 AM - 11:40 AM in 337-338

(ROB-1117-656835) Bioaccumulation and transformation of RDX in the earthworm Eisenia andrei.

Robidoux, PY¹, Sarrazin, M¹, Hawari, J¹, Sunahara, GI¹, ¹ National Research Council Canada, Montreal, Quebec, Canada

ABSTRACT- Energetic compounds can be released into the environment at munitions production and processing facilities, military firing ranges as well as through field use and disposal practices. Based on laboratory studies, 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) has sublethal effects on earthworms at environmentally relevant concentrations in soil. Little information is available describing the bioccumulation and transformation of RDX in soil organisms. In preliminary experiments, the potential bioaccumulation of RDX was assessed using acetonitrile extraction (USEPA Method 8330A) of earthworms exposed to RDX in different substrates. After 72 h exposure on RDX on filter paper, maximum uptake of RDX in earthworms was 506 g/g dry tissue. Exposure to RDX-amended artificial soil for 28 d gave a similar maximum uptake (538 g RDX/g dry tissue). Time-course studies using two different RDX amended natural soils (Sassafras sandy loam, or a Canadian sandy soil) showed that maximum uptake can be attained after 2 d exposure. In addition, earthworm exposure to RDX amended soil led to a time-dependent increase in levels of the RDX metabolite hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), reaching up to 13.7 g/g dry tissue. Acid combustion of [¹⁴C]-RDX exposed earthworms gave similar tissue RDX uptake levels as those using acetonitrile-extracted worms exposed to non-radiolabelled RDX. This information can be used to develop bioaccumulation models that relate soil exposure concentrations to potential bioaccumulation of RDX in the earthworm.

Key words: bioaccumulation, energetic compound, earthworm, metabolites