Survival and reproduction of Enchytraeus crypticus (Oligochaeta, Enchytraeidae) in a natural sandy loam soil amended with the nitro-heterocyclic explosives RDX and HMX

Munition manufacturing, disposal, testing, training and other operations at military sites produced elevated levels of explosives and related materials in soil. The effects of these persistent and highly mobile in the environment energetic materials on soil biota have not been sufficiently investigated. The U.S. Environmental Protection Agency (USEPA) in conjunction with stakeholders, is developing Ecological Soil Screening Level (Eco-SSL) benchmarks for ecological risk assessment (ERA) of contaminants at Superfund sites 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 energetic compounds, RDX and HMX, to soil invertebrates, necessitating toxicity testing. Tests were conducted under conditions preferred for Eco-SSL benchmarks, using a Sassafras sandy loam soil that supports relatively high bioavailability of test compounds. Toxicity testing was performed using enchytraeid reproduction test (ISO/16387 2001) measuring adult survival and juvenile production by the potworm Enchytraeus crypticus in freshly amended soil and weathered/aged amended soil. RDX or HMX had no effect on adult survival in the definitive tests in all treatment concentrations. Juvenile production EC20 values were 3,715 and 8,797 mg kg-1 RDX in freshly amended and weathered/aged amended soils, respectively. Juvenile E. crypticus production was not adversely affected by exposure to HMX in freshly amended and weathered/aged amended soils. Juvenile production was stimulated in freshly amended soil up to 21,750 mg kg-1 HMX. Results of these toxicity studies will be submitted to the Eco-SSL Task Group for quality control review, and pending approval will be included in the Eco-SSL database for Eco-SSL derivation.NRC publication: Ye