(NewsNation) — A study from the National Institutes of Health (NIH) finds that hair straightening chemicals are associated with a higher risk of uterine cancer.

Researchers say women who used hair straightening or relaxer products frequently, more than four times in the previous year, were twice as likely to develop uterine cancer.

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

The study data includes more than 33,000 women in the U.S. ages 35-74. The women were followed for nearly 11 years. In that time, the NIH says 378 uterine cancer cases were diagnosed.

The study warns that Black women may be impacted more due to higher use of the hair products.

“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,” said Che-Jung Chang, Ph.D., an author on the new study and a research fellow in the NIEHS Epidemiology Branch.

Criminal defense attorney April Preyar says she has spoken to about 200 women about the study in the last couple of weeks.

“The one story that stands out is a woman who got a relaxer as a young girl, which is the story I’m hearing over and over, about six or seven years old, and then later developed not only fibroids but also developed endometrial cancer. Now, she’s wondering if this product that she used for all those years was actually the culprit,” Preyar said.

For Preyar, she said it’s heartbreaking to hear one story after the other from women who have had numerous surgeries and now may have some sort of answer.

She said she had hair relaxers from the age of 11 to the age of 25 and that she would get them around every six weeks.

“They (the NIH) saw that it doubled your chances of having endometrial cancer if you had a relaxer even one year for those four times. That’s not the norm. Most people were getting it much more often than that. And then they find themselves with these horrible gynecological conditions years later,” Preyar said.

The NIH did not collect specific information on brands or ingredients in the hair products women participating in the study used. But researchers did note chemicals they say have been found in straighteners like parabens, bisphenol A, metals and formaldehyde.

“Chemical exposure 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,” the NIH said.

Preyar said people should expect to see lawsuits seeking damages against major manufacturers of hair straightening products. She also anticipates changes when it comes to regulations.

“Right now, there are no real regulations required for these products to hit the shelves,” Preyar said. “Not only that, you don’t even have to list all of the ingredients in the United States. You can list them as fragrance and that’s kind of a catch all for the bad.”

The NIH did not collect specific information on brands or ingredients in the hair products women participating in the study used. But researchers did note chemicals they say have been found in straighteners like parabens, bisphenol A, metals and formaldehyde.

“Chemical exposure 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,” the NIH said.

Researchers say, to their knowledge, this is the first epidemiologic study that looked at the relationship between the use of straighteners and uterine cancer. The NIH insists that more research is needed to confirm the findings in different populations and to determine if the hair products are contributing to health disparities.