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SOIL REDUCES 2,4,6-TRINITROTOLUENE BIOAVAILABILITY AND GENOTOXICITY IN VIVO
Citation:
Kohan, M. J., N. Bordelon, L R. Brooks, G. HugginsClark, K. C. Donnelly, AND S E. George. SOIL REDUCES 2,4,6-TRINITROTOLUENE BIOAVAILABILITY AND GENOTOXICITY IN VIVO. Presented at Environmental Mutagen Sociedty Meeting, San Diego, CA, March 16-21, 2001.
Description:
Soil Reduces 2,4,6- Trinitrotoluene Bioavailability and Genotoxicity In Vivo
As chemicals age in soil, irreversible binding of chemical contaminants to organic components in the soil may occur, impacting the amount of chemical that is biologically available upon exposure. In this study, 10 week old Fischer 344 female rats were fed diets prepared with 2,4,6-trinitrotoluene (TNT) contaminated soil obtained from a historical munitions site, to determine if the bioavailablity of TNT is reduced when bound to soil as measured by excretion of mutagenic urine metabolites. Rats were provided food ad libitum prepared with TNT-contaminated soil (3% w/w soil, 1.6 mg TNT/g food), TNT (1.6 mg/g food), clean soil (3% w/w), or no additives for 14 days. On day 14, the rats were placed into metabolism cages, fed the same diets, and urine collected for 24 hours. Urine metabolites were deconjugated by enzymatic treatment (P-glucuronidase and sulfatase) or acid hydrolysis and concentrated. Mutagenic activity was determined in Salmonella typhimurium strains TA98 and TA104l. Even though all groups ingested the same quantity of food, rats that received TNT (with and without soil) in their diets lost weight initially, but by day 14 there was no significant difference between control and treated animals. Animals received an average of 108.8 and 91.3 mg/kg/day of TNT in the presence and absence of soil. In general, after acid hydrolysis, the urine yielded more Salmonella histidine revertants than enzymatic deconjugation. The presence of soil in the TNT diet reduced urine mutagenicity. Acid hydrolyzed urine from TNT- and TNT+soil-treated rats produced 120.0 and 36.0 TA98 revertants/ul urine equivalent and 505.5 and 124.0 TA1041 revertants/ul urine equivalent. Enzymatic deconjugated urine from TNT- and TNT+soil-treated rats generated 58.8 and 34.8 TA98 revertants/ul urine equivalent and 238.7 and 152.2 TA1041 revertants/ul urine equivalent. Reduction in urine mutagenicity suggests that the presence of soil renders TNT less available for metabolism and bioactivation in vivo resulting in reduced genotoxicity.
Abstract does not necessarily reflect EPA policy.