The Story and Science Behind Hair Relaxer MDLs


In December 2019, Eberle, Sandler, Taylor, and White published a study linking permanent hair dye and hair relaxers with breast cancer. This study was then picked up by the media, declaring “Dye, straighteners may increase breast cancer risk.” In the years since, numerous papers have found the use of hair relaxers, products that predominantly black women use to chemically straighten their hair, to be linked with both breast and uterine cancer. And in October 2022, the media picked up on a similar study finding a correlation between regular hair relaxer use and uterine cancer.

Since, thousands of women have filed suit against the makers of these products alleging the use of the aforementioned hair relaxers caused their cancer. In February 2023, these cases were collated into the multidistrict litigation (MDL) In RE: Hair Relaxer Marketing, Sales Practices, And Products Liability Litigation. To date, over 7,000 individuals have joined this suit, most filing in September 2023.

Before the MDL

Before the MDL, these companies dealt with relatively few product liability/personal injury cases. However, two notable cases precede this massive MDL In January 2021, Sharon Dorsey filed suit against Strength of Nature and Walmart over injuries she received allegedly on account of a hair relaxer she purchased. However, in this case, the plaintiff alleged the individual product she bought was defective, not that these products on the whole cause damages. This case was settled in January 2022.

The first suit to allege damages due to hair relaxer use, on the whole, is Price v. Luster Products, Inc. In this case, Britnie Price described how she used Luster’s  PCJ Creme Relaxer from 1999 to 2013, which she alleges caused her uterine fibroids, benign tumors. In later filings, she stated that while training to be a physical therapist, she read “medical articles that correlate the use of hair relaxers and uterine fibroids,” which, she says, led her to suspect that her use of Luster’s relaxer led to her earlier condition. Case documents do not specify which articles led to her belief, and the case was settled out-of-court after thirteen months of litigation. 

The MDL

On October 21, 2022, four days after the publication of “Use of Straighteners and Other Hair Products and Incident Uterine Cancer,” three separate cases were filed in the Northern District of California, the Southern District of New York, and the Northern District of Illinois, two alleging hair relaxers caused uterine cancer and one alleging hair relaxers caused uterine fibroids. In the following weeks, six more complaints were filed making similar claims. 

On February 9, 2023, all nine cases were collated into an MDL in the Northern District of Illinois, where a majority, five, of the suits were filed. In the following months, thousands of plaintiffs filed their own suits, particularly in September 2023, which saw 4,773 new suits. 

The Science

In recent years, dozens of journal articles have been published finding various links between permanent hair dyes, hair relaxers, and breast and uterine cancers. The theory, as the articles and plaintiffs explain, is that chemicals found in these products leach into the body through the scalp, and then disrupt hormone levels. Over time, the theory goes, this disruption leads to an increased risk of developing hormone-related cancer. 

To this end, numerous studies have found leave-in personal care products, which include hair relaxers, are correlated with increased phthalate levels in urine (for review, see Pagoni et al., 2022). A 2016 review of the literature linking hair relaxers and breast cancer states that relaxers contain estrogens, which can promote hair growth but might cause epigenetic changes in breast physiology; phthalates, which serve as fragrance but might also alter breast development; and parabens, which act as a preservative but might lead to cancer cell development.

Additionally, a 2018 study found a link between youth hair relaxer use and experiencing their first period at a younger age. 

However, the path directly linking hair relaxers and cancer is still murky. Numerous studies have found a correlation between hair relaxer use and various hormone-related cancers (e.g. uterine, breast, ovarian); however, these studies all use retrospective data, and few tease out dose level. Retrospective data, while useful and easy to obtain, does not provide the most accurate picture, for participants’ memories are not always the most accurate. In other words, while hair relaxers may be carcinogenic, it is unclear how often an individual has to use them before they are meaningfully increasing their risk for cancer. 

The study that started it all

The strongest study linking hair relaxers and the likely inspiration for this wave of litigation is “Use of Straighteners and Other Hair Products and Incident Uterine Cancer,” which was published in the Journal of the National Cancer Institute. This study used data from the The Sister Study, a prospective cohort of 50,884 who enrolled in 2003-2009. 

As is relevant to this paper, the study asked participants how often they either applied to their own hair or had a professional apply to their hair seven different hair products over the past year. Participants were followed for nine years after recruitment.

The authors found a small but elevated risk of uterine cancer among those who used chemical straighteners more than four times in the previous year compared to those who had not used them. For the frequent use group, 2.41% were predicted to develop uterine cancer by age 70, whereas for the no use group, 1.64% were predicted to develop uterine cancer. The risk for the group that used hair relaxer between one and four times in the previous year was not significantly different from the no use group. 

Considering that these chemical straighteners last between six weeks and six months, according to All Things Hair, at least some women in the frequent use group might have been using the products more often than recommended. 

However, this study does not demonstrate causality. Conducting a true randomized controlled trial with a potential carcinogen could raise ethical issues, and while there are some modern statistical techniques that can get researchers close to the strength of a randomized controlled trial, they require large, expensive studies that in this case would take years, if not decades, to conduct. 

Science in the Courtroom

As discussed in a recent paper by Thomas Albright, science and law have conflicting goals. While both ‘operate through a process of “drawing inferences from evidence to test hypotheses and justify conclusions” (quoting Twining), science he says, uses a “‘generative adversarial’ process that yields ever-growing knowledge and certainty” which conflicts with the “‘terminal adversarial’ approach to truth employed by our courts.” While science seeks the truth through iterative studies and experiments, courts are concerned with drawing the best possible inferences about the here and now situation. Scientists seek to understand; lawyers want to win.

As such, Albright argues that the current system where expert witnesses are retained by the parties themselves only creates confusion and needlessly polarizes issues that might actually be relatively clear-cut. For example, in England and Wales, expert witnesses are brought either by the will of the court or through mutual agreement of the parties. 

Alternatively, Anthony Marcum of R Street argues for a greater use of science days for courts, and especially in the proceedings of large MDLs, for the court to retain independent scientific advisors. As massive MDLs take an increasing share of the federal judiciary’s time, Macum feels we should rethink how they are handled, especially when it comes to matters of science. While judges sometimes make mistakes that critically affect the course of a case, usually they can be corrected by a higher court, and at worst only impact one case. However, when judges presiding over MDLs err in judgment, Marcum warns, the consequences affect thousands of plaintiffs.

Thus, Macum argues, judges should steer clear of a “settle first” mentality and provide decisions and rulings that can be appealed. And in terms of expert witnesses, hopefully set precedent to clarify the Daubert standard.

Both Albright and Macum lament the vagueness of the Daubert standard, and how it puts generalist judges in uncertain waters, with respect to determining the merit of expert witnesses on science. With Daubert and Rule 702, judges are tasked with sifting through who qualifies as an expert without the aid of an independent “science translator.” 

This MDL

Judge ​​Mary M Rowland has been appointed to oversee this MDL. She was appointed to the bench by Donald Trump in August 2019. Prior to her appointment she served seven years as a magistrate judge in the same district. She also spent twelve years as a partner at Hughes, Socol, Piers, Resnick & Dym, and ten years as a federal public defender.

By party, the most targeted companies have been Revlon, Strength of Nature, and Softsheen-Carson.

By firm, the most active firms representing plaintiffs have been Keller Postman, Morgan & Morgan, Singleton Schreiber, and Simmons Hanly Conroy LLC, formerly  Simmons Cooper.