Hair dye does not increase risk of cancer

CANCER DIGEST – Sept. 5, 2020 – A lot of women whose hair color comes from a box can breathe a sigh of relief. After years of suspicion that the chemicals in such permanent hair dye carried health risks, including increased risk of cancer, a new study has found no increased risk linked to most cancers or to cancer deaths in women using the products.

The study involved 117,200 women from the long-running Nurses’ Health Study based at the Brigham and Women’s Hospital in Boston. Those women have been followed for 36 years with a variety of analyses coming from the data gathered over those years. The new analysis was published in the Sept. 2 British Medical Journal (BMJ)
To understand the risk of cancer from personal hair dye the researchers analyzed cancer cases and deaths among the women and compared the results among women who reported ever having used hair dyes and those who had never used such dyes.

They found there was no increased risk of cancers of the bladder, brain, colon, kidney, lung, blood and immune system, or most cancers of the skin, or hormone positive breast cancer. There was an increased risk of three types of breast cancer, those that were estrogen receptor negative, progesterone receptor negative, and hormone receptor negative. There was also a slightly increased risk of ovarian cancer. An increased risk of Hodgkin lymphoma was seen only among women with naturally dark hair.

The researcher caution this is only an observational study, meaning it is based on observed data, not on data from a study designed to compare two groups in a head-to-head comparison. As such this new analysis cannot establish that hair dye does or does not cause cancer. It only says that it doesn’t appear to pose a significantly higher risk.

It also does not address the question of risk posed to hairdressers who are exposed to these chemicals in much higher amounts over much longer period of time. The World Health Organization has classified occupational exposure to hair dye as a probable carcinogen.

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Source: BMJ press release