PHOTOTOXICOLOGY .2. NEAR-ULTRAVIOLET LIGHT ENHANCEMENT OF MICROTOX ASSAYS OF TRINITROTOLUENE AND AMINODINITROTOLUENES

Coexposure of 2,4,6-trinitrotoluene (TNT), 2-amino-4,6-dinitrotoluene (2A), or 4-amino-2,6-dinitrotoluene (4A) to near-ultraviolet (nuv) lig ht (lambda(max)-354 nm) significantly enhanced their toxicity toward P hotobacterium phosphoreum (Microtox bioassay) during 30 min but not 15 min. Based on the slopes of the dose-response lines, the nuv coexposu re and dark toxic mechanisms of action for TNT, 2A, and 4A appeared to be similar. nuv coexposure of binary mixtures significantly enhanced (supraadditivity) the toxicity of these compounds to P. phosphoreum. U nder normal laboratory lighting, the toxicity of TNT + 2A and 2A + 4A mixtures were supraadditive but the toxicity of TNT + 4A mixtures coul d be explained by simple addition. Supporting these conclusions, the r esponse curves of alpha-terthienyl, a compound known not to require nu v for toxicity, were similar in the dark and with nuv coexposure. In c ontrast, angelicin and psoralen, compounds known to require nuv coexpo sure to damage DNA, gave response curves having different slopes in th e dark and with nuv coexposure. The nuv coexposure Microtox assay was able to detect and quantify phototoxicity in psoralen, angelicin, alph a-terthienyl, anthracene, TNT, and aminodinitrotoluenes. (C) 1994 Acad emic Press, Inc.