Abstract
4-Chlororesorcinol is a halogenated phenol that is used as a hair colorant in over 30 hair dye and color products, generally at concentrations <1% Hair dye and color products containing 4-Chlororesorcinol will generally have a warning statement and patch test instructions for determining if each individual user is sensitive to the product before use. The available data do not suggest that 4-Chlororesorcinol is particularly toxic. The oral median lethal dose in rats was 369 mg/kg. Subchronic dermal exposure of rats to a hair dye product containing 2% 4-Chlororesorcinol produced no evidence of compound-induced toxicity. At that same dermal exposure, no embryotoxic or teratogenic effects, no evidence of reproductive toxicity, and no carcinogenic effects were seen. Likewise, 4-Chlororesorcinol was not mutagenic in either a micronucleus or Ames test, not did it induce aneuploidy in neurospora. A 2.5% solution was not a dermal irritant or an ocular irritant in rabbits. While there was some concern that impurity data were not available, the use of actual formulations in the reproductive toxicity and carcinogenicity studies failed to produce any evidence of toxicity. On the basis of the information in the report, it was concluded that 4-Chlororesorcinol is safe as currently used in hair dye formulations.