Hair dye and chemical straighteners linked to increased breast cancer risk, study suggests

Women who use permanent hair dye and chemical straighteners could have a higher risk of developing breast cancer than women who don’t use these products, new research suggests.

A US study, published in the International Journal of Cancer, suggests that breast cancer risk could increase with more frequent use of these chemical hair products.

To study the health risks associated with hair products, researchers at the National Institutes of Health (NIH) and the National Institute of Environmental Health Sciences, analysed data from 46,709 women.

They ranged in age from 35 to 74 and enrolled in the Sister Study, which recruited women whose sisters had been diagnosed with breast cancer.

Researchers analysed answers to questions regarding the women's health, lifestyle and demographics and found that women who regularly used permanent hair dye in the year prior to enrolling in the study were 9% more likely to develop breast cancer than women who didn’t use hair dye.

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African American women polled, who used permanent dyes every five to eight weeks were associated with a 60% increased risk of breast cancer, while white women faced an 8% increase.

The research team found little to no increase in breast cancer risk for semi-permanent or temporary dye use.

All women who chemically straightened their hair at least every eight weeks were 30% more likely to develop breast cancer, but researchers acknowledged these results need to be replicated in other studies.

Commenting on the findings corresponding author Alexandra White, head of the NIEHS Environment and Cancer Epidemiology Group said: “Researchers have been studying the possible link between hair dye and cancer for a long time, but results have been inconsistent.

“In our study, we see a higher breast cancer risk associated with hair dye use, and the effect is stronger in African American women, particularly those who are frequent users.”

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So should women give up dying or chemically straightening their hair in a bid to reduce their breast cancer risk?

Dale Sandler, chief of the NIEHS Epidemiology Branch said that there are many factors that could contribute to an increased breast cancer risk.

“We are exposed to many things that could potentially contribute to breast cancer, and it is unlikely that any single factor explains a woman’s risk,” he said.

“While it is too early to make a firm recommendation, avoiding these chemicals might be one more thing women can do to reduce their risk of breast cancer.”

Following the publication of the study, experts offered a reaction of the study, pointing out some limitations including that “association or correlation does not mean causation.”

“The study analysed data from more than 46,000 women and nearly 2,800 cases of breast cancer. But, only just over 200 of the breast cancer patients were African American, limiting the power to draw conclusions about this group,” Dr Michael Jones, Senior Staff Scientist in Epidemiology, The Institute of Cancer Research in London explained in a statement.

“It’s also important to note that the authors weren’t able to look at the exact ingredients in the hair dyes and chemical straighteners.

“The study was US based, so it’s also not clear if the products would be similar to those used in the UK.”

Paul Pharoah, professor of cancer epidemiology at the University of Cambridge, said: “While these results are intriguing, they do not provide good evidence that hair dyes or chemical straighteners are associated with a meaningful increase in risk of breast cancer or that any increased risk association is causal.

“Women who have used such products in the past should not be concerned about their risks,” he added