Products used to straighten hair increase the risk of uterine cancer, according to a new study published on Monday.
Women who use these products frequently, more than four times a year, are twice as likely to develop cancer of the uterus, especially endometrial cancer. This disease should not be confused with cervical cancer.
“We estimate that 1.64% of women who have never used a hair straightening product will have developed uterine cancer by age 70. But for frequent users, this risk increases to 4.05%”, estimates in a statement Alexandra White, lead author of this study published in Journal of the National Cancer Institute.
“The doubling of this rate is worrying,” he added. Still, uterine cancer is relatively rare, accounting for about 3% of new cancer cases in the United States.
The study is based on data from 33,500 American women, followed for nearly 11 years.
Because black women use these products more often and tend to start out younger, “these results may be particularly interesting for them,” said Che-Jung Chang, co-author of the research.
Approximately 60% of women who said they used hair straightening products in the past year identified as black.
The researchers did not collect information about specific products and brands, but they point out that several chemicals present in these types of products can contribute to an increased risk of cancer: parabens, bisphenol A, metals or even formaldehyde.
The latter, popularly known as formaldehyde, is used for the so-called Brazilian straightening.
Compared to other categories, hair straightening products can promote the absorption of chemicals through injuries or burns to the scalp, or through the use of flat irons, whose heat breaks down the substances, the study points out.
Other studies have already established a link between straighteners and an increased risk of breast cancer.