DiCello Levitt Secures Significant Ruling Preserving Scientific Testimony Linking Hair Relaxers to Uterine and Ovarian Cancer
CHICAGO — A federal judge overseeing the nationwide chemical hair relaxer multidistrict litigation has rejected significant challenges to plaintiffs’ scientific evidence, allowing key expert testimony addressing whether chemical hair relaxer products can cause uterine and ovarian cancer.
In a 65-page opinion issued October 22, 2026, U.S. District Judge Mary M. Rowland of the Northern District of Illinois denied defendants’ motion to exclude the testimony of plaintiffs’ epidemiology expert, Dr. Cote, who concluded that chemical hair relaxers are capable of causing uterine and ovarian cancer. The court also permitted substantial portions of a second expert’s testimony concerning the biological mechanisms through which chemicals in hair relaxers may contribute to cancer development.
“This is an important step forward for the women who have been seeking accountability from the companies that manufactured and marketed these products,” said Diandra “Fu” Debrosse, Co-Chair of DiCello Levitt’s Mass Tort Practice and Co-Lead Counsel in the litigation. “The science is central to these cases, and today’s ruling preserves critical expert testimony addressing the connection between chemical hair relaxers and cancer. We look forward to continuing to advance our clients’ claims and having a jury decide.”
Court Rejects Broad Challenges to Hair Relaxer Cancer Evidence
At issue was whether plaintiffs could present expert testimony establishing general causation—whether chemical hair relaxers are capable of causing uterine or ovarian cancer.
Defendants sought to exclude plaintiffs’ general causation experts, challenging their reliance on epidemiological research, chemical exposure data, and scientific evidence concerning endocrine-disrupting chemicals.
The court rejected several of those arguments. Notably, Judge Rowland determined that experts may evaluate the potential cancer-causing effects of chemical hair relaxers as finished products without necessarily identifying a single responsible ingredient or precise combination of chemicals. Such opinions must still be supported by reliable scientific methods.
The court also found that Dr. Cote reliably evaluated epidemiological studies examining associations between hair relaxer use and uterine and ovarian cancer. Her testimony will be permitted.
Separately, the court allowed toxicologist Mr. Atwood to testify about the biological plausibility of cancer risks associated with mixtures of endocrine-disrupting chemicals, including their potential absorption through the scalp.
Hair Relaxer Litigation Continues in Federal Court
The multidistrict litigation, In re Hair Relaxer Marketing, Sales Practices, and Products Liability Litigation, Case No. 1:23-cv-00818, consolidates lawsuits alleging that manufacturers failed to adequately warn consumers about cancer risks associated with chemical hair relaxer products.
Debrosse filed the first lawsuit in the litigation in October 2022, following publication of a National Institutes of Health-supported study reporting that women who frequently used chemical hair straightening products had more than twice the risk of developing uterine cancer compared with women who did not use them.
DiCello Levitt serves as Co-Lead Counsel in the litigation alongside Ben Crump Law, Motley Rice, and Douglas & London.
About DiCello Levitt
DiCello Levitt LLP is one of the leading plaintiffs’ law firms in the United States. Nationally recognized for our work in high-stakes class actions, mass torts, and complex litigation, we have recovered more than $25 billion for clients, including individuals, businesses, and communities. We take on some of the world’s most powerful interests, pursuing justice that reshapes industries and improves lives.
Built for trial, DiCello Levitt is among the few plaintiffs’ firms with a dedicated trial center, where our acclaimed trial lawyers bring both art and science to courtroom preparation and trial strategy. We are frequently appointed to lead major multidistrict litigation (MDLs) and consistently recognized among the nation’s top plaintiffs’ firms by Chambers USA, Benchmark Litigation, and The National Law Journal, which has named DiCello Levitt Plaintiffs’ Firm of the Year and Trial Strategy Innovation Firm of the Year.
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