The U.S. Food and Drug Administration (FDA) announced its plan to propose a new rule that would ban hair-straightening products (also known as chemical relaxers) because their use has been linked to health risks, including certain hormone-related cancers such as breast cancer and uterine cancer.
The proposed rule would prohibit hair-smoothing products with formaldehyde (FA) and other FA-releasing chemicals (such as methylene glycol) as an ingredient. If the proposed rule is issued, the FDA will invite public comments, and after a review, the agency will decide on further action, according to the FDA guidelines.
How Is Formaldehyde Released in Hair Straightening?
First, the smoothing solution is applied to the hair, followed by a heat processing step, typically with a flat-iron device that seals the solution into pieces of the hair. When the solution is heated, the formaldehyde gas, classified by the International Agency for Research on Cancer as a human carcinogen, is released.
Risk of Uterine Cancer Doubled for Women Who Used Hair Straightening Products
Evidence of the increased risk of certain types of cancer includes the results of a National Institute of Environmental Health Sciences (NIEHS) study published in October 2022 in the Journal of the National Cancer Institute. Researchers found that women who used hair-straightening products frequently (more than four times in the previous year) were more than twice as likely to develop uterine cancer as women who didn’t use the products.
Although the doubling risk was concerning, the authors emphasized that uterine cancer is still relatively rare. According to the findings, an estimated 1.64 percent of women who had never used hair straighteners went on to develop uterine cancer by the age of 70, compared with 4.05 percent of frequent users.
The study also looked at other hair treatments, such as hair dye, bleach, highlights, and perms — and found no increased risk of cancer.
Formaldehyde has long been considered a human carcinogen, on the basis of evidence from occupational and animal studies, says Alexandra White, PhD, a coauthor of the study and the head of the NIEHS Environment and Cancer Epidemiology group in Research Triangle Park, North Carolina.
Research conducted by NIEHS, which is part of the National Institutes of Health, is often used by regulatory agencies such as the FDA to set standards and policies to protect public health and safety, according to Dr. White. “Scientists at the NIEHS will continue to study potential health effects of regular use of hair products.”
Black Women Are Disproportionately Impacted by Straightening Product Risks
In March, the Massachusetts congresswoman Ayanna Pressley and Ohio congresswoman Shontel Brown wrote a letter calling for an investigation by the FDA into the health risks posed by the hair straighteners. Because these products are primarily marketed to and used by Black women, they wrote, “the increased risk disproportionally impacts Black women and contributes to national racial health disparities. The FDA has a mandate to review the latest research and reevaluate the safety of these products,” the representatives wrote.
Investigators in the NIEHS study found that about three in five participants who reported using the straighteners frequently self-identified as Black women.
“Because Black women use hair-straightening or relaxer products more frequently and tend to initiate use at earlier ages than other races and ethnicities, these findings may be even more relevant for them,” said Che-Jung Chang, PhD, a coauthor of the study and a research fellow in the NIEHS Epidemiology Branch, in a press release.
“On behalf of women, especially Black women across the country, I applaud the FDA’s new proposed rule banning formaldehyde and other harmful chemicals from hair straighteners,” said Representative Brown in a press release. “We must ensure the products American consumers buy and use are safe, and I look forward to working with my colleagues and the administration to implement this proposed rule.”
Though Still Rare, Uterine Cancer Rates Are Rising in the U.S.
Uterine cancer occurs when malignant (cancer) cells form in the tissues of the endometrium, which is the lining of the uterus. It accounts for 3.4 percent of all new cancer cases, according to the National Cancer Institute, but it’s the most common cancer of the female reproductive system, with 66,200 estimated new cases in 2023.
Unlike the incidence and death rates of many cancers, uterine cancer rates are rising. New cases have risen by 0.6 percent per year from 2010 to 2019, and death rates have risen an average of 1.7 percent per year during the same time frame.
Aggressive Forms of Uterine Cancer Are Also Rising, Especially in Black Women
Cases of aggressive subtypes of uterine cancer rose rapidly among U.S. women ages 30 to 79 from 2000 to 2015, according to an earlier NIH-sponsored study. The findings also reveal racial disparities, including a higher incidence of these aggressive subtypes and poorer survival — regardless of subtype and cancer stage — among Black women than in women of other racial and ethnic groups.
Until the Proposal Is Made, Products Should Be Used With Caution, if at All
Although the rule hasn’t been proposed yet, the FDA advises women not to apply hair smoothing products at home. If you choose to get the treatments, make sure the salon is properly ventilated.
The agency also advises discussing the product, inquiring about formaldehyde content, and asking about alternative products that don’t release the hazardous gas.
Keep in mind that it can be difficult to tell which hair products contain or can release formaldehyde, according to the Occupational Safety and Health Administration (OSHA). Even products that do not list formaldehyde or methylene glycol on the label, or that claim to be “formaldehyde free” or “no formaldehyde,” can still expose you to formaldehyde.
Products of concern might contain ingredients that are synonyms for formaldehyde or methylene glycol, such as:
- Formalin
- Methanal
- Methanediol
- Formaldehyde monohydrate
Chemicals that release formaldehyde when the product is heated, such as during flat-ironing or blow-drying, include:
- Timonacic acid
- Dimethoxymethane
- Decamethyl-cyclopentasiloxane