Genotoxicity of textile dyes evaluated with Ames test and rec-assay.

We evaluated for mutagenicity 14 commercial textile dyes used extensively in the northern part of India using both the Ames Salmonella typhimurium microsome reversion test as well as the recombination-repair (rec)-assay. The Ames test revealed that 57.14% of dyes were mutagenic and acting directly. The rec-assay detected 50% of dyes to be mutagenic; of these, 71.43% were direct acting, whereas 28.57% required Aroclor-induced exogenous metabolic activation. Used together, the two tests detected 78.57% of the dyes to be mutagenic, and a 50% correlation was found between these two tests. Groupwise, three out of four azo dyes and all five anthraquinone dyes were found to be mutagenic by the Ames assay; the rec-assay detected methine/polymethine (1 out of 3), an oxazine, and a triphenylmethane dye to be mutagenic, besides the azo (1 out of 4) and the anthraquinone (3 out of 5) dyes. The structure-activity analysis attributed the mutagenicity of dyes to the structural alerts such as phenylenediamine, amino and nitro-groups, methylation, CH=CH, and chloro groups; whereas deamination, bulkier groups, and sulfonation may be responsible for diminishing mutagenicity.