If you're looking for a reason to join the natural hair movement, this could be it: Using chemical hair straighteners may come with an increased risk of uterine cancer, according to a new study by the National Institutes of Health. The study of 33,500 women in the US found those who never used chemical hair straighteners had a 1.64% risk of developing uterine cancer before the age of 70. But the risk was doubled—4.05%—for women who used the products frequently, or more than four times in the last year. There was also an increased risk identified for women who used the products infrequently, though it was "not statistically significant and could have been a chance finding," reports the New York Times.
"This doubling rate is concerning," says Alexandra White of the National Institute of Environmental Health Sciences, lead author of the study published Monday in the Journal of the National Cancer Institute, per the Washington Post. "However, it is important to put this information into context—uterine cancer is a relatively rare type of cancer," accounting for 3.4% of all new cancer cases in the US. Just 378 cases of uterine cancer were identified over the study period, running more than a decade. White adds that more research is needed "to determine if hair products contribute to health disparities in uterine cancer, and to identify the specific chemicals that may be increasing the risk of cancers in women."
Researchers, who didn't ask about specific brands or ingredients, note chemical straighteners can contain parabens, bisphenol A, metals, and formaldehyde, which may interfere with the body's hormones. White notes previous research has linked chemical straighteners with other "hormonally driven female reproductive cancers," including of the breast and ovaries, per the Times. The findings are especially important for Black women, who've been discriminated against for having natural hair. They "use hair straightening or relaxer products more frequently and tend to initiate use at earlier ages than other races and ethnicities," says study author Che-Jung Chang. They also "die of uterine cancer at twice the rate that white women do," per the Times. (Read more cancer stories.)