By Claretta Bellamy NBC News

The damage chemical hair relaxers can have on Black women is coming under intense scrutiny. 
Several landmark studies have been published in the last year highlighting the link between chemical hair relaxers — which break down proteins in hair to straighten it — and increased rates of uterine cancer. And last week, after pressure from Democratic Reps. Ayanna Pressley of Massachusetts and Shontel Brown of Ohio, the Food and Drug Administration proposed a ban on hair-smoothing and hair-straightening products containing formaldehyde, an ingredient known to cause cancer. 
As more research continues to reveal potential dangers, hundreds of Black people have filed lawsuits against big-name beauty and cosmetic retailers like L’Oreal and Revlon, blaming their chemical hair straighteners as causes of uterine cancer, fibroid tumors and infertility. 
The latest research on the effects of hair relaxers was published Oct. 10 by Boston University. According to the Black Women’s Health Study, or BWHS, postmenopausal Black women who have used chemical hair relaxers more than twice a year or for more than five years have an increased risk of developing uterine cancer.  
In following 44,798 Black women for up to 22 years, researchers found a higher rate of uterine cancer among postmenopausal Black women who reported having used chemical hair relaxers for at least 10 years, regardless of frequency. 
Better grasping Black health and the factors that contribute to racial disparities in cancer was the intent behind the 22-year study. 
“The idea here is that a renewed emphasis or attention to the potential dangers of these products, I hope, will spur policies, and that will sort of help reduce exposure in this population or even help us identify potentially safer alternatives to straighten hair,” said the lead author of the study, Kimberly Bertrand, an associate professor of medicine at Boston University Chobanian & Avedisian School of Medicine. Revealing the potential risks of hair relaxers, she said, can help spread awareness and encourage making safer choices.
To Rep. Pressley, oversight into these ingredients touches upon generational issue that Black women have long grappled with.
“For generations, systemic racism and anti-Black hair sentiment have forced Black women to navigate the extreme politicization of hair,” she said in a statement to NBC News on Wednesday. “We’ve seen this play out in schools and in the workplace, where Black folks have been criminalized, punished, or overlooked in personnel decisions just for how our hair grows out of our head. As a result, Black women have turned to straightened or relaxed hair as an attempt to advance socially and economically. But regardless of how we wear our hair, we should be able to show up in the world without putting our health at risk, and manufacturers should be prevented from making a profit at the expense of our health.”
NBC News spoke to Bertrand and other researchers to answer some questions Black people may have about chemical hair straighteners and the potential risks to their health
What has the research said about chemical hair relaxers and women’s health so far?
Several studies have found that chemical hair straighteners have harmful effects on the body. Last year, the National Institutes of Health published a major study linking chemical hair straighteners to a higher risk of uterine cancer. The study analyzed data from 33,497 U.S. women ages 35 to 74 who were followed for nearly 11 years. During that period, 378 cases of uterine cancer were diagnosed.
According to this month’s BWHS, women who reported using hair relaxers more than twice a year or who used them for more than five years had a greater than 50% risk of developing uterine cancer compared to those who rarely or never used relaxers, additional data from the study shows. 
In 2021, the BWHS found that Black women who used hair products containing lye, an ingredient typically found in salon relaxers, at least seven times a year for more than 15 years had a 30% increased risk of developing breast cancer. Among the 50,543 women who participated in the 25-year study, 2,311 participants had developed breast cancer, including 1,843 who developed invasive breast cancers, meaning the cancers spread into surrounding breast tissue. While Black women have a 4% lower incidence rate of breast cancer than white women, Black women have a 40% higher breast cancer death rate, according to the American Cancer Society.
Other studies have shown that hair relaxers can cause fibroids and an early onset of puberty in girls, Bertrand said. Early puberty can increase the risk for metabolic syndromes such as obesity, Type 2 diabetes and cardiovascular disease in adulthood. 
Why are hair relaxers so harmful? 
Chemical hair relaxers contain endocrine-disrupting chemicals, which can disrupt the functions of the endocrine system (which includes the thyroid, ovaries, pancreas and adrenal glands) and affect hormone levels. These chemicals include phthalates and parabens, which can be found in relaxers. People can be exposed to them by absorption through the skin or inhaling them in the air. 
Black women are often exposed to endocrine disruptors by using relaxers, which are applied on the scalp, said Jasmine Abrams, a research scientist at the Yale University School of Public Health.
“If you have ever gotten a relaxer, you know it usually sits on for a little bit, and most people sort of alert their hair stylist that it needs to be washed out once it starts tingling or burning — and at that point, you are running the risk of burns,” said Abrams, one of the authors of a study this year linking chemical hair straighteners to issues with fertility. 
“And if you’re running the risk of burns or any sort of injury with that type of chemical,” she added, “then you’re definitely increasing your risk for absorption. If you do that over time for many, many years, then it can, of course, become continuously problematic.”
Endocrine-disrupting chemicals can also be found in some beauty products like lotions, body washes and perfumes, she added. 
Are all chemical hair relaxers dangerous, or are there safer alternatives?
Parabens, phthalates and other chemicals that are often found in chemical hair straighteners pose a greater risk than other products because of scalp exposure, Bertrand said. Even other chemical hair straighteners marketed as safer to use, including no-lye relaxers, still pose potential risks.
“In our study, women who reported using non-lye relaxers were pretty much just as likely to report scalp burns as those who use lye relaxer,” she said. 
Hair-straightening products are “very poorly regulated” by the federal government, Bertrand said, and many mask harmful chemicals under names such as “fragrance and preservatives, so women don’t really know what they’re being exposed to.”
U.S. law does not require the Food and Drug Administration to approve cosmetic products and ingredients, other than color additives, before they go on the market, according to the FDA website. However, the FDA announced last week that it would propose a ban on hair-straightening and hair-smoothing products containing formaldehyde. The FDA did not immediately respond to a request for comment.
Stricter regulations of ingredients in cosmetic products and using alternative methods like heat straightening may help reduce exposure to harmful chemicals, Bertrand said.
In a statement to NBC News on Wednesday, Pressley applauded the FDA, saying the public health of Black women “is at stake.”