Abstract
HC Red #3, also known as N1(2-hydroxyethyl)-2-nitro-p-phenylenediamine, is a colorant used in semipermanent hair dyes. Unidentified nitrosamines were found in two lots of HC Red #3, at concentrations of 20 ± 5 ppm and 11 ± 8 ppm. The LD50 for HC Red #3 was >500 mg/kg in mice and >1000 mg/kg in rats. In a subchronic feeding study, the mean body weights of male mice and rats were reduced. Other than a pigmentation of the urine and some organs of these animals, no gross or microscopic changes due to HC Red #3 were noted. HC Red #3 was mutagenic in the Ames assay; the mutagenicity was greatly increased by metabolic activation. In a two-year feeding study, there was no evidence of carcinogenicity produced in either male or female rats. There was equivocal evidence for the carcinogenicity of HC Red #3 in male mice and inadequate evidence to make a judgement of carcinogenicity in female mice. On the basis of the available data presented in this report, it is concluded that HC Red #3, which does not contain nitrosamines and used in products not containing N-nitrosating agents, is safe as a “coal tar” hair dye ingredient at the current concentrations of use.