Straightening products used to straighten hair, especially by black women, pose an increased risk of uterine cancer, according to a major new study from the US Institute of Health.
Women who use these products frequently — more than four times a year — see their risk of developing uterine cancer more than double, according to this work.
Independent experts have praised the usefulness of this research on a subject that has so far been little studied, and published on Monday in the Journal of the National Cancer Institute. They invoked one “precautionary principle” to call for more regulations, although further studies are needed to further investigate these findings.
Uterine cancer (not to be confused with cervical cancer) is a relatively rare form of cancer. It accounts for about 3% of new cancer cases in the United States, with about 66,000 cases and 12,500 deaths in 2022.
But the incidence of this cancer is increasing in the United States, especially among black women.
The study is based on data from nearly 33,500 American women, recruited between 2003 and 2009 and followed for nearly eleven years. A total of 378 women developed uterine cancer.
For women who have never used hair straightening products, the risk of developing uterine cancer in their 70s is 1.64% compared to 4.05% for frequent users, described in a press release Alexandra White, lead author of the study.
“Because black women use hair straightening or straightening products more frequently and tend to start younger… these findings could be of particular interest to them.”, emphasized Che-Jung Chang, co-author of this work.
As part of this study, about 60% of women who said they used hair straightening products during the year declared that they were black.
Hormone disrupting drugs
The researchers did not collect information about the specific products and brands used.
But they note that several frequently used chemicals can contribute to increasing the risk of cancer: parabens, bisphenol A, metals or even formaldehyde.
Formaldehyde, commonly known as formaldehyde, can be used in particular for so-called Brazilian leveling – at limited prices in certain countries, including France. It is classified as carcinogenic.
Another potential mode of action could be disruption of hormonal mechanisms.
“We know that these smoothing products contain many chemicals, including endocrine disruptors, and they can be expected to have an impact on hormone-dependent cancers.”explained to AFP Alexandra White. “The concern is that these items contain chemicals that can act like estrogen in the body.“, she added.
Previous work by the researcher had already raised a link between relaxing products and an increased risk of breast and ovarian cancer.
During the study, no similar association was observed between uterine cancer and other techniques such as dyes, bleaches or perms.
Hair straightening products can promote the absorption of chemicals via lesions or burns caused by the scalp or by joint use of straighteners, the heat of which breaks down the chemicals.
In a commentary published simultaneously, experts judged that it was “time to intervene”.
Changes “in terms of personal care, there is probably a need for products on many levels”they wrote, especially to “challenging race-based beauty standards”and at “lack of transparency about chemicals” Used.