A federal lawsuit listing L'Oreal USA and various other companies, claims these businesses sell products that cause cancer and other health problems. It also alleges that the companies knew, or should have known, that the use of the dangerous chemicals in the products would increase the risk of cancer; yet they marketed and sold them anyway, and alleges these companies failed to provide a warning to women.
Dozens of plaintiffs, predominantly Black women, are pointing to a study published in the Journal of the National Cancer Institute in October 2022 that found an association between the frequent use of hair-straightening products and uterine cancer.
The study found that those who self-reported the regular use of straightening products, such as relaxers, were twice as likely to later develop uterine cancer than women who did not use the products, but there was not enough evidence to prove the hair straightener caused the specific cancer.
"We know now that these chemicals are responsible for the tragic number of users' reproductive cancer," Ben Crump, an attorney for the plaintiffs, said in an official statement. "This litigation will bring justice to these women and their families and hold corporations that put profits over people accountable for their deadly actions."
Rhonda Terell, one of the plaintiffs named in the lawsuit, said she found out she had cancer on Christmas Eve in 2019.
Terell told ABC News that she began using relaxers when she was 9 years old and did not stop using them until her mid-thirties. She said hair relaxers were "just part of being an African American girl."
"I had no idea that the chemicals I was putting on my head would lead to this diagnosis," Terell said.
According to the study, women who self-reported using straightening products are more likely to develop uterine cancer than women who don't, and most of the women who use straightening products are African American and Black women. While the study saw no evidence that race itself increases the risk of uterine cancer, the negative health effects associated with straightener use could be worse for African American and Black women because of their more frequent use of straightening products, younger age at which they start, and the harsher chemicals used for their hair.
"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%," Dr. Alexandra White, the study's lead author, said in a summary of the study released in October by the National Institutes of Health. The study defined frequent use as the use of straightening products more than four times per year.
"We are confident in the safety of our products and believe the recent lawsuits filed against us have no legal merit. L'Oréal upholds the highest standards of safety for all its products. Our products are subject to a rigorous scientific evaluation of their safety by experts who also ensure that we follow strictly all regulations in every market in which we operate," L'Oréal said in a statement to ABC News.
Strength of Nature Global, LLC, another defendant listed in the litigation, declined to comment on the lawsuit at this time.
While uterine cancer represents around 3% of all cancer cases, it is the most common of gynecological cancers in the nation, according to the Centers for Disease Control and Prevention.
Although the study found a correlation between cancer and hair straighteners, researchers did not identify a particular ingredient in the trial and stated that more research is needed.
"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," White wrote in the study's summary.
Terell's lawyer, Danielle Mason, said that she has also used chemical hair straighteners and shares concerns about the products.
"For science to put the health disparities and these very disproportionate outcomes of fibroids and cancer and other reproductive harms that are predominant in Black women … at the forefront of their study so that we can get to the bottom of all of the things that are going on with us, so that we can make more informed choices," Mason told ABC News.
The study included more than 33,000 women between the ages of 35 to 74, with around 60% of women who reported using chemical straightening products self-identified as Black women.
Crump is joined by attorney Diandra "Fu" Debrossee Zimmerman as co-lead counsel for the plaintiffs -- marking the first time that a Black man and a Black woman have been appointed as co-leads of multidistrict litigation in federal court, according to a statement put out by Ben Crump Law.
This lawsuit comes just months after Jenny Mitchell filed an initial case suing five beauty companies, claiming she had to have a hysterectomy for the cancerous effect of their products.
"I'm hoping to be the voice for millions of other African American women out there," Mitchell said. "I don't want another me at 28 not being able to have a family of your own."
Crump and Zimmerman say they expect hundreds more plaintiffs to join the case.
ABC News' Eric Jones and Halle Kendall contributed to this report.