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.