Cancer Myth:Hair dyes and cancer
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Origin of the myth
Many hair dyes used before 1980 contained tar-like compounds to darken hair. Women
who used these dyes were found to have an increased risk of bladder cancer. These
chemicals were also found to cause cancer in mice. As a result of these findings many
women refused to colour their hair, forcing cosmetics companies to find new
ingredients to darken hair. The carcinogenic (cancer causing) chemicals are now banned
in several countries.
Current evidence
Hair dyes come in two forms – oxidative (permanent) and non-oxidative (semi-permanent
and rinses). Most studies have focused on the permanent or oxidative hair
dyes.
The International Agency for Research on Cancer (IARC) evaluated hair dyes in 1993
and concluded that they were possibly carcinogenic to humans. This judgement was
based on studies which had found an increased risk of bladder cancer amongst
hairdressers and barbers who are highly exposed to the chemicals in hair dyes. The
evaluation also found mixed evidence for increases in lung cancer and non-Hodgkin
lymphoma as a result of hair dye exposure.[1]
Since this evaluation, more studies have been conducted assessing the link between
hair dyes and cancer.
In 2002, the Yale school of Public Health studied 1200 women, half of which had been
diagnosed with breast cancer and half of who were unaffected by the disease. There
women were interviewed as to whether they had used hair dye, which colours and
products they had used, and for how long and how often they had done so. The study
found no connection between use of hair colour and development of breast cancer.[2]
A study conducted in Sweden of more than 45,000 hairdressers found no increase in
the incidence of bladder cancers for hairdressers in recent decades. Researchers
concluded that modern dyes were not linked with bladder cancer. The incidence of
other cancers linked to hair dye also dropped consistently until, in the 1990-1998
period, it was no longer statistically significant.[3]
Summary
These studies should give reassurance that the link between using modern hair dyes
and cancer are, at most, very minimal.[4] People who colour their hair are unlikely to have
an increased risk of cancer, even if they have been colouring their hair regularly for
many years. If you are still concerned, ensure that you colour your hair in a well
ventilated room or salon, so as to minimise exposure to the fumes from hair dyes.
Otherwise, embrace your natural colour.
References
1. IARC Working Group., IARC working group on the evaluation of carcinogenic risks to humans:Occupational exposures of hairdressers and barbers and personal use of hair colourants; some hair dyes, cosmetic colourants, industrial dyestuffs and aromatic amines., in IARC Monogr. Eval. Carcinogen. Risks Hum 1993: Lyon, France. p. 7-398.
2. Zheng, T., et al., Use of hair colouring products and breast cancer risk: a case-control study in Connecticut. Eur J Cancer, 2002. 38(12): p. 1647-52.
3. Czene, K., S. Tiikkaja, and K. Hemminki, Cancer risks in hairdressers: assessment of
carcinogenicity of hair dyes and gels. Int J Cancer, 2003. 105(1): p. 108-12.
4. Takkouche, B., M. Etminan, and A. Montes-Martinez, Personal use of hair dyes and risk of cancer: a meta-analysis. JAMA, 2005. 293(20): p. 2516-25.
