CYTOTOXICITY AND MUTAGENICITY OF 2,4,6-TRINITROTOLUENE AND ITS METABOLITES

Composting has been advocated and is being used as an economical metho d for remediating 2,4,6-trinitrotoluene (TNT)-contaminated soils. Howe ver, evidence suggests that TNT is transformed into products of unknow n toxicity during the process. This study was undertaken to examine th e in vitro cytotoxicity and mutagenicity of TNT and several of its deg radation products/metabolites. TNT was equally cytotoxic to H4IIE cell s and Chinese hamster ovary-gl (CHO) cells (LC(50) of 4 g/ml vs 24 mu g/ml, with overlapping 95% prediction intervals), indicating that TNT does not need to be metabolized to exhibit cytotoxicity. Four metaboli tes studied, 4-hydroxylamino-2,6-dinitrotoluene; 2-amino-4,6-dinitroto luene; 4,4',6,6'-tetranitro-2,2'-azoxytoluene; and 2,2',6,6'-tetranitr o-4,4'-azoxytoluene, were equally cytotoxic to both H4IIE and CHO cell s. The LC(50)s were in the 3- to 18-mu g/ml range and were not signifi cantly different from TNT cytotoxicity in both cell lines. 4-Amino-2,6 -dinitrotoluene (4-A) was moderately less cytotoxic than TNT to H4IIE cells, but was noncytotoxic to CHO cells. This result indicates that i i-A is metabolized to a cytotoxic compound. Both TNT and its metabolit es exhibited only slight mutagenicity at high doses in one or both of the mutagenicity assays. While composting may reduce the levels of TNT in composted material, the hazard associated with TNT-contaminated so ils is probably lower, but still uncertain. (C) 1996 Academic Press.