P-Toluenediamine hair dyes induce cellular proliferation and genotoxicity

Abstract

The p-toluenediamine (TDA) is a precursor agent, which is widely used in oxidative hair dye formulations. Its oxidant form reacts with one or more couplers in an alkaline medium to produce a certain color. During application, topical products can be absorbed, leading to systemic effects in the organism exposed to them. To assess the toxicity of the penetrated part, five oxidative hair dyes containing p-toluenediamine sulfate as the precursor were analyzed in vitro. The selected dyes were the most widely used brands in the markets. The solutions of the dyes which represented the absorbed part of the hair dye were prepared by Franz cell. Varied concentrations of solutions dyes were added to the human kidney cell line ( HEK293T) to evaluate the cytotoxicity and genotoxicity. The cytotoxic effect was measured by Thiazolyl Blue Tetrazolium Bromide assay (MTT assay), whereas the genotoxicity was detected by Micronucleus test. The MTT assay showed inducing cell proliferation exposed to different hair dye solutions after incubation for 24 hours. The induction was significant with formulations 1,3,4, and 5. The maximal growth reached 180% with hair dye 1, while the decrease in growth rate appeared with hair dye 2 . Micronucleus test on HEK293T cell line showed a significant increase in the number of micronuclei in all treatments with different potencies according to the formula. The micronucleated cells ranged between 2.5-4.2-fold compared to the control. The highest value appeared with hair dye 3, with micronucleated cells approximately 4.2-fold; in contrast, the increase was the lowest with hair dye 2. Therefore, hair dye - 2 did not show ability to induce proliferation and micronucleated cells significantly, so it was considered the least genotoxic among the studied hair dyes. In conclusion, the absorbed amount of hair dye containing TDA could induce the growth rate of cells and cause a genotoxic effect.