Chemicals in Hair Straighteners May Increase Uterine Cancer Risk

Many of us use hair products regularly to help with unruly strands or to give us a different look than our default. A new study, though, finds that one product in particular may increase the risk of uterine cancer.

Recent research from the National Institute of Environmental Health Sciences (NIEHS) examined the link between several common hair products and uterine cancer incidence, finding that those who used chemical hair straighteners had more than double the risk of developing the disease than those who did not. The findings, published in the Journal of the National Cancer Institute, did not establish such a link for other types of products, like bleach, dye, or perms.


Dr. Alexandra White, lead author and head of the NIEHS Environment and Cancer Epidemiology group, says, “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%. This doubling rate is concerning. However, it is important to put this information into context – uterine cancer is a relatively rare type of cancer.”

To conduct their study, the team used data from nearly 33,500 women between the ages of 35 and 74 who have participated in the Sister Study, an NIEHS effort to determine risk factors for breast cancer and other diseases. Within 11 years, 378 of these women had developed uterine cancer. The team discovered that the risk of this happening was more than double among women who reported using hair straighteners more than four times per year, compared to those who did not use them.

Researchers say this could be due to a variety of chemicals within these products, including parabens, bisphenol A, metals, and formaldehyde. The risk may be especially strong because of these chemicals being absorbed into the scalp, particularly within burns and other injuries caused by the straighteners.


The team also notes that the issue could be more significant to Black women, as 60% of participants who used straighteners self-identified as Black.

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

It is important to note, however, that the study did not find different uterine cancer incidence by race among those who reported using straighteners.

The team says going forward, more research needs to be done to confirm the link between uterine cancer and hair straighteners among different populations and to determine which chemicals may be behind this increased prevalence. The study does, however, build on previous research finding a link between hormone-based cancers and hair straightener use.


In past research, the team had also found a link between permanent hair dye and straighteners and breast and ovarian cancer risk.

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