Hair straightening chemicals linked to higher risk of uterine cancer

News release

Monday, October 17, 2022

An NIH study found that black women may be more affected due to higher use.

Women who used chemical hair straightening products were at higher risk of uterine cancer than women who did not report using these products, according to a new National Institutes of Health study. The researchers found no association with uterine cancer for other hair products the women reported using, including hair dyes, bleach, highlights or perms.

The study data included 33,497 US women aged 35-74 who participated in the Sister Study, a study led by the National Institute of Environmental Health Sciences (NIEHS), part of the NIH, that sought to identify cancer risk factors of the breast and other health conditions. The women were followed for almost 11 years and during that time 378 cases of uterine cancer were diagnosed.

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 develop uterine cancer as those who did not. have used the products.

“We estimated that 1.64% of women who never used a hair straightener would develop uterine cancer by age 70; but for frequent users, that risk is as high as 4.05%,” said Dr. Alexandra White, head of the NIEHS Cancer Environment and Epidemiology Group and lead author of the new study. “This rate of doubling is disturbing. However, it is important to put this information into context – uterine cancer is a relatively rare type of cancer.

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 new cases projected in 2022. Studies show that the incidence of uterine cancer is increasing in the United States, especially among Black women.

Approximately 60 percent of participants who reported using a hair straightener in the previous year were self-identified black women, according to a study published in the Journal of the National Cancer Institute. Although the study did not find that the association between sit-up press use and uterine cancer incidence differed by race, adverse health effects may be greater in black women due to more frequent use.

“Because black women use hair straighteners or relaxers more often and tend to start using them at an earlier age than other races and ethnicities, these findings may be even more relevant to them.” , said Che-Jung Chang, Ph.D., an author on the new study and a research associate in the NIEHS Epidemiology Branch.

The findings are consistent with previous studies showing that sit-ups may increase the risk of hormone-related cancers in women.

The researchers did not collect information about brands or ingredients in the hair products the women used. However, in the paper they note that several chemicals found in hair straighteners (such as parabens, bisphenol A, metals and formaldehyde) may contribute to the observed increased risk of uterine cancer. Chemical exposure from the use of hair products, especially curling irons, may be of greater concern than other personal care products due to increased absorption through the scalp, which may be exacerbated by burns and lesions caused by curling irons.

“To our knowledge, this is the first epidemiologic study to examine the relationship between press use and uterine cancer,” White said. “More research is needed to confirm these findings in different populations, to determine whether hair products contribute to health disparities in uterine cancer, and to identify the specific chemicals that may increase women’s cancer risk.” “

This team previously found that permanent hair dye and press can increase the risk of breast and ovarian cancer.

Grant numbers: Z01-ES044005, Z1AES103332-01

About the National Institute of Environmental Health Sciences (NIEHS): NIEHS supports research to understand the effects of the environment on human health and is part of the National Institutes of Health. For more information about NIEHS or environmental health topics, visit or subscribe to a news list.

For the National Institutes of Health (NIH):NIH, the national agency for medical research, includes 27 institutes and centers and is part of the US Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research and investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit

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Che-Jung Chang, Katie M. O’Brien, Alexander P. Keil, Symielle A. Gaston, Chandra L. Jackson, Dale P. Sandler, Alexandra J. White. Use of straightening irons and other hair products and incidence of uterine cancer. Journal of the National Cancer Institute DOI: (2022).


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