Are Chemical Hair Straighteners Increasing Your Risk of Uterine Cancer?

Chemical hair straighteners

Fast Facts

Study Origin: Conducted by the National Institutes of Health (NIH)

Duration: Over a decade-long study

Participants: 33,947 women, aged 35-74

Key Finding: Frequent use of chemical hair straighteners doubles the risk of uterine cancer

Disproportionate Impact: Black women are more likely to be affected

Women who frequently use chemical hair straighteners may face a higher risk of uterine cancer, according to new research. The study, conducted by the National Institutes of Health (NIH) and published in the Journal of the National Cancer Institute, highlights that Black women, who predominantly use these products, could be disproportionately affected.

Study Findings

The study followed thousands of women for over a decade to examine their use of hair products. The results revealed that frequent use of chemical hair straighteners more than doubled the risk of developing uterine cancer compared to those who did not use these products.

Lead author Alexandra White, PhD, head of the National Institute of Environmental Health Sciences’ (NIEHS) Environment and Cancer Epidemiology group, noted, “To our knowledge, this is the first epidemiologic study that examined the relationship between straightener use and uterine cancer.”

Disproportionate Impact on Black Women

The study underscores that Black women may be particularly at risk due to their higher and earlier use of hair straighteners. Among the study participants who reported using chemical hair straighteners in the past year, 60% identified as Black women. Che-Jung Chang, PhD, an author of the study, emphasized that these findings are especially relevant for Black women who use these products more frequently and start at younger ages.

Research Methodology

Researchers collected data from 33,947 participants in the US, aged 35 to 74, all of whom had a uterus at the start of the study. These participants were part of the Sister Study, aimed at identifying risk factors for breast cancer and other health conditions.

Participants filled out a questionnaire about their use of various hair products, including dyes, straighteners, relaxers, and pressing products, within the past 12 months. Over the next 11 years, researchers monitored their health, recording any new cancer diagnoses. During the study, 378 women (about 1% of participants) were diagnosed with uterine cancer, including endometrial cancer, uterine sarcoma, and other uterine cancers.

Increased Risk with Frequent Use

Women who used chemical hair straighteners more than four times per year had a two-fold greater risk of uterine cancer compared to non-users. Notably, other hair products like permanent and semi-permanent hair dyes, bleach, and highlights were not associated with an increased cancer risk.

Despite the significant increase in risk, White pointed out that uterine cancer remains relatively rare. However, the rates of this cancer have been increasing in the US, especially among women of color. Oliver Dorigo, MD, PhD, a gynecologic oncologist at Stanford University, noted that uterine cancer is one of the fastest-growing cancers in the US, particularly among Black, Asian, and Hispanic women.

Previous Links to Hormone-Related Cancers

These findings align with previous research suggesting that chemical hair straighteners may be linked to hormonally-mediated health outcomes. Earlier studies by the NIEHS team found that permanent hair dyes and chemical straighteners can increase breast cancer risk. Regular use of permanent hair dyes increased breast cancer risk by 9%, while frequent use of hair straighteners increased the risk by 30%.

Black women faced higher risks with these hair products. Frequent use of permanent hair dye was associated with a 60% increased risk of breast cancer among Black women, compared to an 8% risk among white women.

Potential Harmful Chemicals

Chemical hair straighteners

Hair products often contain chemicals like parabens, bisphenol A, metals, and formaldehyde, which may act as carcinogens or endocrine disruptors. The scalp’s high absorption rate and potential for burns or lesions during application might amplify exposure to these harmful substances.

Need for Further Research

The research is still in early stages, and more studies are needed to understand the link between hair products and cancer. Identifying specific ingredients responsible for the increased cancer risk is crucial.

Recommendations for Hair Product Use

Health experts aren’t yet making specific recommendations on hair straightener use. While the overall risk of uterine cancer is low, those who frequently use chemical hair straighteners might consider reducing their use. Regular physical activity, which reduces chronic inflammation, may help offset cancer risk for frequent users, although more research is needed to confirm this.

Proceed with Caution

Although no specific brands or ingredients were studied, the NIEHS findings suggest caution when using chemical hair straighteners. More research is necessary to confirm these results and to understand the disproportionate impact on ethnically diverse populations.

Troy Gatcliffe, MD, a gynecologic oncologist, advises, “This epidemiological evidence shouldn’t necessarily scare women to stop using straighteners altogether but provides evidence that they should be used with caution and under advisement.”


While the findings are significant, uterine cancer remains rare. It’s essential for users of chemical hair straighteners to be aware of the potential risks and consider moderation in their use until further research provides clearer guidance


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