Genotoxic activity of five haloacetonitriles: Comparative investigations in the single cell gel electrophoresis (Comet) assay and the Ames-fluctuation test

Halogenated acetonitriles (HANs) are known to be water disinfectant by-prod ucts. Their mutagenicity and carcinogenicity have been shown in different t est systems in vivo and in vitro. They also have clastogenic properties. In this study, the ability of HAN to induce single-strand breaks on the DNA o f Hela S3 cells was investigated using the single-cell gel electrophoresis (SCGE) assay, which could be a good tool with which to evaluate the genotox icity of chlorinated water. The results were compared to those obtained in the Ames fluctuation test using the Salmonella typhimurium TA 100 strain wi thout activation. With the Ames fluctuation test, a mutagenic effect was ob served for chloroacetonitrile (MCAN), dichloroacetonitrile (DCAN), and tric hloroacetonitrile (TCAN). No mutagenic effect was Found with bromoacetonitr ile (MBAN) or dibromoacetonitrile (DBAN). In the SCGE assay, all five HANs induced DNA damage in Hela S3 cells, increasing the mean toil moment signif icantly. For each compound, a dose-effect relation was observed. This study shows that the SCGE assay has greater sensitivity For assessing the genoto xicity of HAN than does the Ames-fluctuation test. Brominated acetonitriles were more genotoxic than chlorinated acetonitriles in the SCGE assay, and the genotoxicity increased with the number of halogenated atoms of the comp ound. This behavior had already been Found with other genotoxicity tests. E nviron. (C) 2000 Wiley-Liss, Inc.