Hair dyes

General information

Hair dyes (for example henna, paraphenylenediamine, and paratoluenediamine) have been reviewed [ ]. They have moderate to low acute toxicity. Poisoning is rare and occurs only after oral ingestion. Contact sensitization usually occurs from unprotected professional exposure, but the prevalence has stabilized or fallen over the years. In vitro genotoxicity tests of hair dye ingredients have often been positive, but the relation to in vivo carcinogenicity is not clear and there is no in vivo evidence of genotoxicity. Despite the results of various studies that have suggested an association between the use of hair dyes and bladder cancer, a number of studies, including prospective investigations in large populations and systematic reviews, have shown no convincing associations with bladder cancer and other cancers. The results of direct toxicity studies and epidemiological studies suggest that hair dyes and their ingredients do not cause adverse reproductive effects.

Organs and systems