Hair Straightening Chemicals Linked to Higher Uterine Cancer Risk

WASHINGTON — Women who use chemical hair straightening products are at a higher risk for uterine cancer compared to women who do not report using these products, according to a new study from the National Institutes of Health.

The researchers found no associations with uterine cancer for other hair products that the women reported using, including hair dyes, bleach, highlights or perms.

However, the same team previously found that permanent hair dye and straighteners may increase breast and ovarian cancer risk.

Their latest findings were published in the Journal of the National Cancer Institute.

The study data includes 33,497 U.S. women ages 35-74 participating in the Sister Study, a study led by the National Institute of Environmental Health Sciences, part of NIH, that seeks to identify risk factors for breast cancer and other health conditions.

The women were followed for almost 11 years and during that time 378 uterine cancer cases were diagnosed.

The researchers found that women who reported frequent use of hair straightening products, defined as more than four times in the previous year, were more than twice as likely to go on to develop uterine cancer compared to those who did not use the products.

“We estimated that 1.64% of women who never used hair straighteners would go on to develop uterine cancer by the age of 70; but for frequent users, that risk goes up to 4.05%,” said Alexandra White, Ph.D., head of the NIEHS Environment and Cancer Epidemiology group and lead author on the new study, in a written statement.

“This doubling rate is concerning. However, it is important to put this information into context — uterine cancer is a relatively rare type of cancer,” White said.

Approximately 60% of the participants who reported using straighteners in the previous year were self-identified Black women.

While the study did not find that the relationship between straightener use and uterine cancer incidence was different by race, the adverse health effects may be greater for Black women due to higher prevalence of use.

Uterine cancer accounts for about 3% of all new cancer cases but is the most common cancer of the female reproductive system, with 65,950 estimated new cases in 2022.

Studies show that incidence rates of uterine cancer have been rising in the United States, particularly among Black women.

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