Hair straighteners were associated with an 18% increase in breast cancer risk.
Among 46,709 participants, the researchers from the National Institute of Health reported that women who permanently dyed their hair before participating in the study were 9% more likely to develop breast cancer than those who didn't color their hair. Even so, it might be wise to avoid chemical straighteners and permanent hair dyes, she said.
Researchers have found that women who use permanent hair dye and chemical hair straighteners have a higher risk of developing breast cancer than women who don't use these products.
Black women face higher risks of breast cancer. The findings suggest that hair dyes and chemical straighteners may increase Black women's risk of developing breast cancer.
"Researchers have been studying the possible link between hair dye and cancer for a long time, but results have been inconsistent", Alexandra White, Ph.D., a study author and head of the National Institute of Environmental Health Sciences (NIEHS) Environment and Cancer Epidemiology Group, said in a press release. The risks were the same for Black and white women but "straightener use was much more common among African American women".
Well, breast cancer is rarely caused by one thing only.
When asked if women should stop using such hair treatments, the study investigators replied that it is too early to make any firm recommendations.
The U.S. Federal Drug Administration (FDA), the agency that oversees the regulation of hair dyes, says on its website it does not "have reliable evidence showing a link between cancer and coal-tar hair dyes on the market today".
"There are many points that I take issue with in this study", said Dr. Lauren Cassell, chief of breast surgery at Lenox Hill Hospital in New York City.
Age is also a factor: breast cancer incidence rates were higher among African-American women younger than 60 years old but lower among those who are 60 or older. Many women interviewed in the study might also not accurately recall frequency of use, or whether they used permanent or semi-permanent dyes, Cassell reasoned. The study published online December 4 in the International Journal of Cancer and suggests that breast cancer risk increased with more frequent use of these chemical hair products.
The study was published online December 4 in the International Journal of Cancer.
Scientists also found that the risk increased among women who treated their hair with the products on a more regular basis.