According to the International Agency for Research on
Cancer (IARC), some
hair dyes are considered mutagenic and carcinogenic in in vitro assays and exposed human populations. Epidemiological studies indicate that hairdressers occupationally exposed to
hair dyes have a higher risk of developing
bladder cancer. In Brazil, 26% of the adults use
hair dye. In this study, we investigated the toxic effects of two
hair dyes,
Basic Red 51 (BR51) and
Basic Brown 17 (BB17), which are temporary
dyes of the azo group (R-N=N-R'), used in the composition of the black
hair dye. To this end, MTT and
trypan blue assays (cytotoxicity), comet and micronucleus assay (genotoxicity) were applied, with HepG2 cells. For cytotoxic assessment,
dyes were tested in serial dilutions, being the highest concentrations those used in the commercial formula for
hair dyes. For genotoxic assessment concentrations were selected according to cell viability. Results showed that both
dyes induced significant cytotoxic and genotoxic effects in the cells, in concentrations much lower than those used in the commercial formula. Genotoxic effects could be related to the azo structure present in the composition of the
dyes, which is known as mutagenic and carcinogenic. These results point to the hazard of the
hair dye exposure to human health.