Abstract
HC Yellow No. 2 is used in oxidative or semipermanent hair dye formulations in concentrations up to 1%. The LD50 for HC Yellow No. 2 administered via gavage was between 1.2 and 2.5 g/kg in male rats and between 0.6 and 1.2 g/kg in female rats. In the subchronic and chronic feeding studies, 1.25% HC Yellow No. 2 reduced body weight gain and induced changes in various organ sizes and clinical chemistry values. The only histologic change attributed to this hair dye was a small increase in the pigment of the spleen. The compound was only a minor ocular irritant when tested at a concentration of 10%. It was neither a sensitizer nor photosensitizing agent in guinea pigs at 10%. It was not a teratogenic compound in rats. HC Yellow No. 2 was negative in a dominant lethal assay and it was not mutagenic in the four S. typhimurium strains tested, both with or without S9 metabolic activation. In a repeated insult patch test (RIPT) using 3% HC Yellow No. 2, two volunteers of 98 had a positive reaction to the test substance. In another RIPT study, 1 of 104 volunteers had a sensitization reaction to 3% HC Yellow No. 2. It is concluded that HC Yellow No. 2 is safe for use in hair dyes at concentrations up to 3%.