Lawsuits Filed Regarding the Use of Hair Straightening Products and an Increased Risk of Uterine Cancer. In 2022, a National Institutes of Health study found that women who reported frequent use of chemical hair straightening or relaxing products were more than twice as likely to develop uterine cancer as compared to those who did not use the products. Frequent use was defined as use of the hair straightening or relaxing products four or more times in the previous year. The researchers found no associations for other hair products—such has hair dyes, bleach, highlights or perms—and uterine cancer in women. The study looked at approximately 33,500 women ages 35 to 74 years old. These women were followed for nearly 11 years, and 378 uterine cancer cases were diagnosed. Studies have also shown that use of chemical hair straightening products may lead to an increased risk of breast and ovarian cancer.

Approximately 60% of the women who reported use of chemical hair straightening or relaxing products self-identified as Black women. It is important to note that given the higher prevalence of use of these products among Black women, the adverse health effects may be more consequential for African American and/or Black women.

Chemical hair straightening and relaxing product formulations typically contain hazardous chemicals, including phthalates, parabens, bisphenol A, metals and formaldehyde. The endocrine-disrupting chemicals found in chemical hair straightener and relaxing products may have contributed to cancer risk. Endocrine disruptors, such as formaldehyde and phthalates, interfere with hormone functions, such as the natural production of developmental, reproductive, immunity and neurological hormones.