Uterine cancer can refer to either endometrial cancer, uterine sarcoma, or other rare forms of cancer that can arise in your uterus.
33,497 women in the US took part in the study and after 11 years, 378 were diagnosed with cancer.
• The report notes that several chemicals were found in the straighteners, including parabens, bisphenol A, metals, and formaldehyde.
• Parabens are a group of chemicals that keep mold and bacteria from growing in beauty products.
The study, published Monday in the Journal of the National Cancer Institute, estimates that among women who did not use hair-straightening chemical products in the past 12 months, 1.6% developed uterine cancer by age 70, but about 4% of the women who frequently use such hair-straightening products developed uterine cancer by age 70.
Research findings published in the journal of the National Cancer Institute said black women are at a higher risk because they use straightening products at younger ages, at higher rates, and use higher concentrations.
“We 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,” lead author Alexandra White said.
He said those who used the straighteners, locally known as ‘chem’ (short for chemicals) more than four times in the previous year were more than twice as likely to develop uterine cancer compared to those who did not use the products.
“This doubling rate is concerning. However, it is important to put this information into context – uterine cancer is a relatively rare type of cancer,” White said.
The researchers said that the study did not rely on differences between racial and ethnic groups, just the frequency of use of the products.
The researchers did not also collect information on brands or ingredients in the hair products the women used.
However, in the report notes that several chemicals were found in the straighteners, including parabens, bisphenol A, metals, and formaldehyde.
Parabens are a group of chemicals that keep mold and bacteria from growing in beauty products.
But in humans, parabens can mimic the hormone estrogen, possibly fueling dangerous cell growth, according to research.
These chemicals could be contributing to the increased uterine cancer risk observed, the study warned.
Chemical exposure resulting from hair product use, especially straighteners, could be more concerning than other personal care products due to increased absorption through the scalp which may be exacerbated by burns and lesions caused by straighteners.
“To our knowledge, this is the first epidemiologic study that examined the relationship between straightener use and uterine cancer,” White said.
“More research is needed to confirm these findings in different populations to determine if hair products contribute to health disparities in uterine cancer and to identify the specific chemicals that may be increasing the risk of cancers in women,” he added.
A 2021 study by the same team of researchers also found an association between permanent hair dye and straightening chemicals with a higher risk of ovarian cancer.
Some 33,497 women in the US aged between 35-74 participated in the Sister Study, a study led by the National Institute of Environmental Health Sciences (NIEHS), part of NIH, that seeks to identify risk factors for breast cancer and other health conditions.
The women were followed for almost 11 years and during that time, 378 uterine cancer cases were diagnosed.