The link between certain chemical hair straighteners, such as relaxers and pressing treatments, and uterine cancer has long been debated, but recent studies have helped to further support the claims. In the past, research has suggested that certain hair products may contain hazardous chemicals with carcinogenic properties, such as formaldehyde and other endocrine-disrupting chemicals, linking them to hormone-related cancers, such as breast and ovarian cancer. These new studies, however, look into a link between chemical hair straighteners containing these specific chemicals and an increased risk of uterine cancer specifically.
On Oct. 10, 2023, researchers at Boston University’s Black Women’s Health Study (BWHS) published their latest findings, which looked at 44,798 participants, following them from 1997 to 2019. They defined “heavy use” as using hair relaxers at least five times a year for longer than 15 years and “infrequent use” as less than one to two times a year for fewer than four years. “Compared to women who never or rarely used hair relaxers, those who reported using hair relaxers more than twice a year or for more than five years had a greater than 50 percent increased risk of uterine cancer,” writes the Boston University Chobanian & Avedisian School of Medicine.
The study concludes that “long-term use of chemical hair relaxers was associated with increased risk of uterine cancer among postmenopausal women, but not among premenopausal women.”
Prior to this, the first study to ever explore this topic was by the Journal of the National Cancer Institution, published on Oct. 17, 2022. The research was conducted on 33,947 participants with a uterus between the ages of 35 and 74. During the study, they self-reported the hair products they used over the last 12 months, including “hair dyes; straighteners, relaxers, or pressing products; and permanents or body waves.”
At the time of the follow-up, which came at an average of 10.9 years later, it was reported that 378 uterine cancer cases were identified. Only 1.6 percent of those who did not report using hair straightening products in the past 12 months developed uterine cancer by 70, while 4 percent of those who frequently (defined as more than four times in a year) used them did. “Use of other hair products, including dyes and permanents or body waves, was not associated with incident uterine cancer,” the research states.
“In this study, women with frequent use in the past year had an over two-fold higher risk of uterine cancer,” Chandra Jackson, an author of the study and researcher at the National Institute of Environmental Health Sciences, told CNN.
While Boston University’s Black Women’s Health Study only looked at women who self-identify as Black, the Journal of the National Cancer Institution study included a range of participants. Despite making up only 7.4 percent of the study participants, Black women accounted for up 59.9 percent of subjects who had reported ever using straighteners. “The bottom line is that the exposure burden appears higher among Black women,” Jackson said.
Both of these studies hope to raise awareness of the risks associated with the use of hair relaxers. Kimberly Bertrand, ScD, associate professor of medicine at Boston University Chobanian & Avedisian School of Medicine, says in the release, “Identification of safer alternatives to straightening hair, stricter regulation of cosmetic products, and policies to prohibit discrimination against natural hair such as the CROWN Act could represent important steps toward reducing racial disparities in uterine cancer.”
