Can harsh chemical ingredients in hair relaxers that break down hair bonds and damage fragile tresses also increase women’s risk of breast cancer?

Over the past few years, there’s been much research about possible associations between chemical straighteners and African-American women’s health. Now recent findings published in the journal Carcinogenesis have found no clear link between most of these hair products and breast cancer risk, BreastCancer.org reports.

For the study, researchers reviewed information about lifestyle factors from more than 50,000 participants in the U.S. Black Women’s health study—a large-scale investigation begun in 1995 to learn why this population group experiences higher rates of certain illnesses, such as breast cancer, high blood pressure, diabetes and stroke, compared with women of other races.

Scientists assessed how often participants used hair relaxers between 1997 and 2017 and the type of hair relaxer they used. Next, researchers compared this data to women’s medical records to look for links between these hair straighteners and breast cancer risk.

Results showed that 70% of Black women in the study were moderate users of chemical relaxers (usage of more than three times a year, four or more years with any frequency or 15-plus years fewer than seven times a year); 20% were heavy users (usage of 15-plus years, seven or more times a year); 5% were light users (hair relaxed fewer than three times a year); and 5% never used these products.

In addition, scientists noted that 71% of these participants used no-lye relaxers, 16% used lye-containing products and 13% of the women were unsure which type of relaxer they used.

Of these women, 2,311 were diagnosed with breast cancer of the following types during the study period: 1,420 estrogen-receptor-positive, 601 estrogen-receptor-negative and 286 triple-negative cancers.

What’s the takeaway? “Our results are generally reassuring,” said Kimberly Bertrand, ScD, an assistant professor of medicine at Boston University School of Medicine and the study’s lead author. “We found no clear evidence that hair relaxer use is associated with breast cancer risk for most women.” 

That said, researchers did note a slightly increased risk for estrogen-receptor-positive breast cancer among heavy users of hair relaxers with lye.

However, before researchers can say definitively that these products are connected to the development of breast cancer, scientists must produce similar results from a number of studies.

In the meantime, scientists suggest that Black women who frequently use lye-containing relaxers should discuss these findings with their doctor, opt for no-lye straighteners or relax their hair less often.

To learn more about safer ways to straighten Black hair, read “A Relaxing Chat: Tips for At-Home Hair Straightening.”