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Energetic materials are employed in a wide range of commercial and military activities and often are released into the environment. Scientifically based ecological soil-screening levels (Eco-SSLs) are needed to identify contaminant explosive levels in soil that present an acceptable ecological risk. Insufficient information for 2,4,6-trinitrotoluene (TNT) to generate Eco-SSLs for soil invertebrates necessitated toxicity testing. We adapted the standardized Enchytraeid Reproduction Test and selected Enchytraeus crypticus for these studies. Tests were conducted in Sassafras sandy loam soil, which supports relatively high bioavailability of TNT. Weathering and aging procedures for TNT amended to test soil were incorporated into the study design to produce toxicity data that better reflect the soil exposure conditions in the field compared with toxicity in freshly amended soils. This included exposing hydrated TNT-amended soils in open glass containers in the greenhouse to alternating wetting and drying cycles. Definitive tests showed that toxicity for E. crypticus adult survival and juvenile production was increased significantly in weathered and aged soil treatments compared with toxicity in freshly amended soil based on 95% confidence intervals. The median effect concentration and 20% effective concentration for reproduction were 98 and 77 mg/kg, respectively, for TNT freshly amended into soil and 48 and 37 mg/kg, respectively, for weathered and aged TNT soil treatments. These findings of increased toxicity to E. crypticus in weathered and aged TNT soil treatments compared with exposures in freshly amended soils show that future investigations should include a weathering and aging component to generate toxicity data that provide more complete information on ecotoxicological effects of energetic contaminants in soil.

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The U.S. Environmental Protection Agency is developing ecological soil screening levels (Eco-SSLs) for the ecological risk assessment of contaminants at Superfund sites. The Eco-SSLs for several soil contaminants have been developed from toxicity benchmarks for soil invertebrates in the existing literature. Insufficient information to generate Eco-SSLs for Sb, Ba, and Be necessitated toxicity testing to fill the data gaps. We used standardized toxicity tests with the earthworm Eiseniafetida, enchytraeid Enchytraeus crypticus, and collembolan Folsomia candida in the present study. These tests were selected on the basis of their ability to measure chemical toxicity to ecologically relevant test species during chronic assays and their inclusion of at least one reproduction component among the measurement endpoints. Tests were conducted in Sassafras Sandy Loam soil, which supports relatively high bioavailability of metals. Weathering and aging procedures for metals in amended soil were incorporated into these studies to better reflect exposure conditions in the field. The relative toxicity of metals to the soil invertebrates tested was Be > Sb > Ba based on the median effective concentration values for reproduction. These studies produced toxicological data that can contribute to the development of Eco-SSLs for Sb, Ba, and Be for soil invertebrates.