Chemical straighteners and permanent hair dyes are two of the most common beauty products for women, but a new study published in the International Journal of Cancer stated that these may be linked to an elevated risk for breast cancer.
Hair dyes have been associated to other cancers before, though the research is inconclusive. Blood and bladder cancers have been examined closely, according to the American Cancer Society, with the most consistent results pointing to a small increase in bladder cancer risk for salon employees. Most studies in the past that are looking at dye and breast cancer have not found a connection.
The same thing is unclear for hair straighteners. While most studies that used data from the mid-1990s did not find a connection between straighteners and breast cancer, the more recent studies have, and the researchers behind the new paper note that some straightening formulas that were popularized since the 1990s, like keratin treatments, have been found to either contain the carcinogen formaldehyde or release it during the application process.
Dangers of hair dyes and straighteners
The new study funded by the NIH or the National Institutes of Health and the National Institute of Environmental Health Sciences studied 46,700 American women who were enrolled in the Sister Study, which included women who do not have breast cancer but whose sisters had been diagnosed with the disease.
During enrollment, the women ranged in age from 35 to 74. They all answered questions about their lifestyle, health, and demographics at the beginning of the study, and they provided researchers with updates over a follow-up period of eight years.
More than half of the women reported using permanent hair dyes in the year before they joined the study, and 10% said that they had used chemical straighteners. These women had a greater chance of being among the 2,800 study participants who ended up developing breast cancer, especially if they identified as black.
Using permanent dye was linked with a 9% higher risk of developing breast cancer, compared to those who don't use them. But black women who were reported to use permanent dye had a 45% higher risk of breast cancer, compared to non-users, and those who used these products every eight weeks or more usually had a 60% higher risk.
The study also found out that black women were far more likely to report using chemical straighteners, around 74% of them had, compared to 3% of white women, which were linked with an 18% higher risk of breast cancer in the study population as a whole.
Breast cancer risk
An epidemiologist from the National Institute of Environmental Health Sciences and author of the study, Alexandra White, said that the level of cancer risk among black women may be due to the differences in the formulations of the hair dyes and straighteners used by black women compared to those used by white women.
Dale Sandler, White's co-author, stated that coarser, thicker hair may also absorb more dye. More research is needed to confirm those hypotheses, but Sandler says that it is important for doctors to know about the differences, especially since black women are more likely to die from breast cancer than white women, and since previous researches on the health effects of hair dye have been on white women.
Unfortunately, there is no quick fix or any specific ingredient to avoid at this point. White says that hair dye contains more than 5,000 different compounds and formulas are changing constantly. Some compounds have had more evidence to support their possible carcinogenicity than others.
White says that for breast cancer, some of the strongest evidence points to aromatic amines, colorless chemicals in hair dye that has been shown to bind to DNA in breast tissue, and lead to DNA damage linked to cancer. Temporary and semi-permanent dyes contain fewer aromatic amines, making them safer than permanent dyes.
The study is a reminder that self-care and beauty products in America are not well-regulated. The vast majority of cosmetic products and ingredients do not need Food and Drug Administration approval or safety testing before they are released in the market, and the agency does not have the authority to recall tainted products.
Although it is worth being conscious of the risks linked with cosmetics, White says that it is too soon to swear off hair dye. The study tracked a small group of women who developed cancer, and the disease is almost never caused by one thing alone. There are a lot of different factors that can influence breast cancer risk.
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