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Hair relaxer and other chemical hair straightening products may be linked to an increased risk of developing uterine cancer among those who use them frequently, suggests a new study published in the Journal of the National Cancer Institute on Oct. 17, 2022.

Study leader Alexandra White of the U.S. National Institute of Environmental Health Safety (NIEHS) said in a statement, obtained by Reuters, that researchers "estimated that 1.64 percent 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 percent."

White said in the statement that adding context to this information is important because uterine cancer is a relatively rare disease. However, the U.S. Centers for Disease Control and Prevention (CDC) reports that uterine cancer is the most common gynecologic cancer in the United States, and rates are rising particularly among Black women. Of the 33,947 racially diverse women, ages 35 to 74, 378 developed uterine cancer during the nearly 11 years the researchers tracked them. 

After the study researchers accounted for other risk factors for the disease among the participants, they found that women who used hair straightening products more than four times in the previous year were at a greater risk of developing uterine cancer. Those who used the products less frequently in the past year had an elevated uterine cancer risk that could be attributed to chance, since the difference was statistically insignificant, report Reuters.

The study didn't find a link between straightener use and uterine cancer along racial lines, but since Black women use hair relaxers and other chemical straightening 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 Che-Jung Chang of NIEHS in a statement.

Past research has found a connection between hair straightening products, which contain so-called endocrine disrupting chemicals, and the development of breast and ovarian cancers. However, White and colleagues wrote in the Journal of the National Cancer Institute that their "findings are the first epidemiologic evidence of association between use of straightening products and uterine cancer. More research is warranted to ... identify specific chemicals driving this observed association."