BIOAVAILABILITY OF TNT RESIDUES IN COMPOSTS OF TNT-CONTAMINATED SOIL

Composting is being explored as a means to remediate 2,4,6-trinitrotol uene (TNT) contaminated soils. This process appears to modify TNT and to bind it to organic matter. The health hazards associated with dusts generated from such materials cannot be predicted without knowing if the association between TNT residues and compost particulate is stable in biological systems. To address this question, single doses of [C-1 4]-TNT, soil spiked with [C-14]-TNT, or compost generated with [C-14]- TNT-spiked soils were administered to rats by intratracheal instillati on. The appearance of C-14 in urine and tissues was taken as an indica tion of the bioavailability of TNT residues from compost particles. In rats instilled with neat [C-14]-TNT, about 35% of the C-14 dose appea red in urine within 3 d. The C-14 excreted in urine by these rats decr eased rapidly thereafter, and was undetectable by 4 wk after treatment . Similar results were obtained with soil-treated rats. In contrast, a fter treatment with [C-14]-TNT-labeled compost, only 2.3% of the total C-14 dose appeared in urine during the first 3 d Low levels of C-14 c ontinued to be excreted in urine from compost-treated rats for more th an 6 mo, and the total amount of C-14 in urine was comparable to that in TNT-treated animals. Determination of the radiolabel in tissues sho wed that C-14 accumulated in the kidneys of rats treated with labeled compost but not in rats treated with [C-14]-TNT or [C-14]-TNT-spiked s oil. These results indicate that the association between TNT and parti culate matter in compost is not stable when introduced into the lungs. Accumulation of C-14 in kidneys suggests the presence of a unique TNT residue in compost-treated rats. The rate of excretion and tissue dis position of C-14 in rats treated with TNT-spiked soil indicate that TN T in soil is freely available in the lungs.