Hair Relaxer MDL 3060: The Scientific Evidence and Causation Questions Shaping the Litigation

A Large Docket Is Not Proof

More than 12,000 federal hair-relaxer lawsuits are pending in Chicago, but the size of the litigation does not establish causation. The central dispute is scientific as to whether research linking certain hair-straightening practices to reproductive cancers can support reliable expert testimony under Federal Rule of Evidence 702.

In re: Hair Relaxer Marketing, Sales Practices, and Products Liability Litigation is pending in the Northern District of Illinois before Judge Mary M. Rowland. The Judicial Panel on Multidistrict Litigation reported 12,381 actions pending as of October 1, 2026, and 16,828 total historical actions. These are action counts, not verified numbers of individual women or unique claimants and exclude claims that may exist in state court. ^[1]

The court held a Science Day in January 2026 to consider competing scientific theories, without deciding causation or liability. No global settlement had been publicly confirmed as of the research cutoff. The current bellwether schedule should be verified against the court docket.^[2]

What The Science Shows And Does Not Show

A 2022 Sister Study analysis followed 33,497 participants for an average of 10.9 years and identified 378 uterine cancer cases. Compared with women reporting no straightener use in the preceding year, those reporting use more than four times had an adjusted hazard ratio of 2.55 (95% confidence interval, 1.46–4.45). NIH reported modeled cumulative risks by age 70 of 4.05% for frequent users and 1.64% for never-users. ^[3]

These observational findings do not establish individual causation. Product use was self-reported, and researchers did not test every historical formulation. Further research is needed to identify the chemicals potentially responsible for the association.^[4]

Other studies report mixed findings. A 2023 Black Women’s Health Study analysis of 44,798 women found an overall hazard ratio of 1.18 (95% CI, 0.81–1.71) for heavy relaxer use and uterine cancer, with higher estimates in certain postmenopausal subgroups. Separate research associated frequent straightener, relaxer or pressing-product use with ovarian cancer, but not ever-use. These findings do not establish a single causal explanation for reproductive conditions.^[5]

The Rule 702 Gate

Federal Rule of Evidence 702, amended effective December 1, 2023, requires the proponent to show that it is more likely than not that proposed expert testimony meets the rule’s admissibility requirements. The inquiry includes whether an expert’s methods are reliable and reliably applied to the facts, and not merely whether the expert is qualified.

Under Daubert[6], Joiner[7], and Kumho Tire[8], courts examine whether expert reasoning reliably connects evidence to conclusions. Excluding general-causation testimony could jeopardize dependent claims, while admission would not establish liability. Plaintiffs must still prove product identification, exposure, injury and causation under applicable law.

Product Identity, Equity, and FDA rulemaking

Complaints allege that certain hair-relaxing or straightening products exposed users to chemicals affecting hormonal pathways and contributed to reproductive injuries. Defendants dispute liability and causation. Because ingredients can vary by brand, product line, and year, the analysis must focus on the product actually used.

The litigation also raises environmental-justice questions. Research has examined how racialized beauty norms and commercial markets may shape exposure patterns. In the Sister Study, 59.9% of participants who had used straighteners were African American or Black. That context matters to public-health research, but does not establish the MDL’s demographic composition or causation in an individual case. ^[9]

FDA’s RIN 0910-AI83 concerns formaldehyde and formaldehyde-releasing chemicals in certain heated hair-smoothing products. As of October 9, 2026, the proposal remained pending, with November 2026 listed as a projected date. It does not automatically cover traditional relaxers.^[10] Separately, 21 U.S.C. § 379s(d) preserves state product-liability law against the specified cosmetic-labeling preemption provision.^[11]

Practical Points For Counsel

Counsel should document product brand and line, years and frequency of use, application method, packaging or purchase evidence, and possible formulation changes. Medical records should establish diagnosis, pathology, treatment chronology, and relevant history. Experts should address absolute and relative risk, confidence intervals, subgroup results, confounding, exposure uncertainty, and the inferential link between population-level association and the individual claim. MDL No. 3060 remains scientifically contested. Epidemiological associations warrant investigation but do not establish product-specific causation. Rule 702 will test expert reliability, while plaintiffs must independently prove exposure, injury and causation.

^[1] Judicial Panel on Multidistrict Litigation, “MDL Statistics Report-Distribution of Pending MDL Dockets by Actions Pending” (Oct. 1, 2026), MDL No. 3060 entry. Source: Official JPML report.

^[2] In re Hair Relaxer Marketing, Sales Practices & Products Liability Litigation, MDL No. 3060, Memorandum Opinion and Order Regarding Bellwether Selection Schedule and Procedures (N.D. Ill. Jan. 31, 2025) (Dkt. 1052). Source: Read order; see also N.D. Ill., Multidistrict Litigation page, MDL No. 3060; Marin & Murphy, “Hair Relaxer Lawsuit Update.” Sources: Official court MDL page; Secondary docket tracker (Marin & Murphy).

^[3] Che-Jung Chang et al., “Use of Straighteners and Other Hair Products and Incident Uterine Cancer,” 114 Journal of the National Cancer Institute 1636, 1636–1645 (2022), doi:10.1093/jnci/djac165. Source: Read full journal article; see also National Institutes of Health, “Hair Straightening Chemicals Associated with Higher Uterine Cancer Risk” (Oct. 17, 2022). Source: Read NIH summary.

^[4] See Chang et al., “Use of Straighteners and Other Hair Products and Incident Uterine Cancer”, supra note 4; see also See NIH, “Hair Straightening Chemicals Associated with Higher Uterine Cancer Risk”, supra note 5.

^[5] Katherine A. Bertrand et al., “Hair Relaxer Use and Risk of Uterine Cancer in the Black Women’s Health Study,” 239 Environmental Research 117228 (2023), doi:10.1016/j.envres.2023.117228. Source: Read full journal article; see also Alexandra J. White et al., “Use of Hair Products in Relation to Ovarian Cancer Risk,” 42 Carcinogenesis 1189 (2021), doi:10.1093/carcin/bgab056. Source: Read full journal article; and Lauren A. Wise et al., “Hair Relaxer Use and Risk of Uterine Leiomyomata in African-American Women,” 175 American Journal of Epidemiology 432 (2012), doi:10.1093/aje/kwr351. Source: Read full journal article.

[6] Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993)

[7] General Electric Co. v. Joiner, 522 U.S. 136 (1997)

[8] Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999)

^[9] See Chang et al., “Use of Straighteners and Other Hair Products and Incident Uterine Cancer”, supra note 4; see also Jasmine A. McDonald et al., “The Environmental Injustice of Beauty Products: Toward Clean and Equitable Beauty,” 112 American Journal of Public Health 50 (2022), doi:10.2105/AJPH.2021.306606. Source: Read full article.

^[10] U.S. Department of Health and Human Services, Food and Drug Administration, Unified Agenda, RIN 0910-AI83, “Use of Formaldehyde and Formaldehyde-Releasing Chemicals as an Ingredient in Hair Smoothing Products or Hair Straightening Products” (2026 agenda). Source: Read Unified Agenda entry.

^[11] 21 U.S.C. § 379s(d) (cosmetic-labeling preemption; no effect on product-liability law).