Effects of repeated applications of two semi-permanent hair dyes to the skin of A and DBAf mice.

Two proprietary semi-permanent hair dyes were tested for carcinogenicity in A and DBAf mice by repeated topical applications in aqueous acetone. Mice of both strains developed lymphoid tumours but experimental differences were marked only in DBAf mice. A number of tumours of the ovary and uterus, and some skin papillomas near the penis, occured in dye-treated but not in control DBAf mice. As many hair-dye constituents are known mutagens, adequate carcinogenicity testing of these substances, and epidemiological study of exposed human populations, are needed for evaluating possible health hazard from hair dyeing.