Study links hair-straightening chemicals to uterine cancer, putting Black women more at risk

Using hair-straightening products with chemicals could raise the risk of developing uterine cancer – the most common cancer affecting the female reproductive system in the U.S. – and Black women may be most at risk, according to a recent study.

The National Institutes of Health research was part of the 50,000-population Sister Study, which examines risk factors for breast cancer and other health issues. More than 34,000 women ages 35-74 participated in the research for nearly 11 years, during which time there were 378 uterine cancer diagnoses, according to the NIH.

The research previously found using permanent hair dyes and chemical straighteners could heighten risks for ovarian and breast cancers.

“Hair products are a potential source of exposure to chemicals, including both endocrine disruptors that impact our normal hormonal system as well as potential carcinogens,” lead researcher Alexandra White told USA TODAY. White works with the NIH Environment and Cancer Epidemiology group.

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Women who reported using hair-straightening products – permanent processes like chemical relaxers, for example – more than four times in a year were more likely to get uterine cancer at some point than a person who didn’t use those products, according to the study.

Researchers estimated 1.64% of women who never used hair-straightening products would develop uterine cancer by age 70, but the risk is greater, at 4.05%, for frequent users.

Black women more likely to be affected

Black women have been particularly impacted by the recent rise in U.S. uterine cancer cases overall, according to a May study from the NIH.

The study did not show that straightener use and uterine cancer rates differed by race, White said, nor did it find that Black women more susceptible to these chemicals.

"It's not that the chemicals are necessarily conferring a higher risk in Black women, it's just that we know Black women are much more likely to be using these products, using them more frequently and to start at an earlier age," White said. About 60% of the people in the study who reported using straightening products in the past year were Black women.

"It's really that the burden of this exposure falls more heavily on this population," White said, pointing toward societal pressure to conform to beauty standards as a reason Black women use straighteners more frequently.

"I recognize that for some women, just quitting using these hair-straightening products is really not an option."

Black women also face increased risks from breast cancer, uterine fibroids, diabetes and other illnesses, said Dr. Jessica Shepherd, chief medical officer at Verywell Health

"Unfortunately, this isn’t all too surprising," Shepherd, a board-certified OB-GYN, told USA TODAY of the study's findings.

"While things like product use and lifestyle are a big factor, a lot of this is also due to lack of health insurance and bias in health care," she said. "Black women can opt not to use certain hair straighteners, but these systemic issues still largely exist and play a role."

How chemicals may contribute to higher cancer risk

Nearly 66,000 uterine cancer cases have been reported this year in the U.S., and the cancer makes up about 3% of all new cancer cases, according to the NIH.

Breast, uterine and ovarian cancers are known to have a strong hormonal cause, White said.

“They are all influenced by our endocrine system, so it made sense that (if) we see these associations with breast and ovarian that we might also see it with uterine,” White said.

While the study didn't collect details on specific products or ingredients women are using, researchers pointed out chemicals like formaldehyde and parabens that could be contributing to the higher uterine cancer risk.

Other than color additives, the chemicals used in cosmetic products don't need approval from the U.S. Food and Drug Administration before hitting the market, according to the FDA.

The findings did not show a heightened uterine cancer risk for other hair products, such as bleach or dye, White said.

"That's reassuring in some ways," she said, adding that reducing the frequency of these products could reduce a person's chemical burden.

"Ideally, we'd like to make sure that the chemicals in these products are safe for people, and that could mean more testing of chemicals in the products, and California has passed legislation that requires labels on products that identify them as containing potentially hazardous chemicals."

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This article originally appeared on USA TODAY: Hair straightening product chemicals linked to uterine cancer: Study