MEMPHIS, Tenn. — A new study from the National Institutes of Health shows women who use hair straightening or relaxing products are at greater risk for developing uterine cancer.

The NIH also found more black women may be affected due to higher use.

The Sister Study looked at 33,497 women in the U.S. ages 35-74. The women were followed for almost 11 years, and 378 uterine cancers were diagnosed during that time.

The researchers discovered women who frequently used straightening products were twice as likely to develop uterine cancer compared to women who did not use the products.

Dr. Alexandra White, head of the National Institute of Environmental Health Sciences and Cancer Epidemiology and lead author of the study, said the doubling rate is concerning. However, it is important to note that uterine cancer is a relatively rare type of cancer.

The study estimated that 1.64% of women who never use hair straighteners would go on to develop uterine cancer by the age of 70, and for frequent users, the risk went up to 4.05%.

Eumecca Long with A Natural Affair Beauty Lounge in Memphis said she was not shocked by the findings but would like to know more about what exactly is causing the cancer.

“The study was dealing with if it had formaldehyde in it. It did not specify the brands,” said Long.

Long said their salon does not use straightening products or relaxers, which are also harsh on hair, and said today there are a lot more choices for black women who want to go the natural route.

“We even use natural hair color,” said Long. “Our owner has developed a line of products that are great for natural hair styling.”

The researchers didn’t collect information on brands or ingredients in the hair products the women used. However, in the paper, they noted that several chemicals found in straighteners, like parabens, bisphenol A, metals, and formaldehyde, could be contributing to the increased uterine cancer risk.

The said chemical exposure from hair products used is more concerning than other personal care products due to increased absorption through the scalp, which burns and lesions caused by straighteners may exacerbate.

The same researchers found that permanent hair dyes and straighteners may increase your risk of breast and ovarian cancer.