Hair-straightening chemical products linked to increased uterine cancer risk

Women who use hair-straightening chemicals are at higher risk for uterine cancer compared to those who don’t, a new study by the National Institutes of Health has found.

The study, published this week, found that of the 33,497 participants, those who used chemical products designed to straighten their hair more than four times a year were more than twice as likely to develop uterine cancer.

The researchers followed the large group of women, who were between the ages of 35 and 74, for 11 years. In that time, 378 cases of uterine cancer were diagnosed.

The study estimates that among women who did not use hair-straightening chemical products in the past 12 months, 1.6 per cent were diagnosed with uterine cancer by age 70. However, around four per cent of women who frequently used the products developed the cancer by age 70.

Chandra Jackson, an author of the study and researcher at the National Institute of Environmental Health Sciences (NIEHS), noted that while uterine cancer is rare, the “doubling of risk does lead to some concern.”

“In this study, women with frequent use in the past year had an over two-fold higher risk of uterine cancer,” she told CNN.

Previous and ongoing research has suggested that the use of certain hair products, including hair-straightening chemicals, can be linked to some hormone-driven cancers, like breast cancer and ovarian cancer. This is the first time a study has linked the product to uterine cancer, specifically.

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The chemicals contained in many hair-straightening products that are linked to cancer are known as endocrine disrupting chemicals.

“These products can contain a lot of different chemicals of concern,” Alexandra White, head of the NIEHS Environment and Cancer Epidemiology group and lead author on the study, said in a release.

Researchers, however, did not find a strong relationship between other hair treatments – such as dyes and perms – and uterine cancer.

Black women may be more affected due to higher use of hair-straightening products than their counterparts, health experts warn. Approximately 60 per cent of the study’s participants who reported using straighteners in the previous year self-identified as Black.

“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 Dr. Che-Jung Chang, author of the study and research fellow in the NIEHS Epidemiology Branch.

Uterine cancer is the most common cancer of the female reproductive system, and according to the Canadian Cancer Society, rates of uterine cancer in Canada have been rising steadily for the past 30 years.

It is most often seen in women over the age of 50 and is more common in white women. However, anyone with a uterus is at risk of developing uterine cancer.