How long does it take for science to identify a new type of harm from commercial activity before litigation tries to hold the businesses accountable?

It has been more than 50 years since scientists determined that some environmental chemical exposures can affect our health by interfering with how our hormones function. Theo Colborn coined a term for this phenomenon more than 30 years ago: Endocrine Disrupting Chemicals, or EDCs. There was one early warning in the form of the 1970s litigation over the synthetic estrogen diethylstilbestrol (DES), in which plaintiffs alleged in utero DES exposure caused the daughters of the women who took it to develop vaginal and cervical cancers later in life. With the benefit of hindsight, we know that the DES litigation was about endocrine disruption before it was named as such.

But now, after the long wait, endocrine disruption has firmly arrived in litigation in 2023.

Scientists have discovered hundreds of commonly used chemicals can disrupt our endocrine systems, leading to myriad health conditions like metabolic syndrome and infertility. Endocrine disruption is also tightly linked to developmental disorders, especially when a developing fetus is exposed in the womb. The evidence is sufficiently strong that some scientists believe EDCs are a major cause of the so-called “diseases of modern living” that are on the rise in Western countries.

Despite the clear evidence that EDCs have population-level effects, the DES litigation was, until recently, the only example of endocrine disruption litigation. The recent start of mass litigations involving hair relaxer and acetaminophen (also called paracetamol and APAP) is the first time since the DES litigation that endocrine disruption takes center stage.

In the multidistrict litigation alleging hair care products cause cancer, complaints state: “This action arises out of [plaintiff’s] diagnosis of uterine cancer. [Her] uterine cancer was directly and proximately caused by her regular and prolonged exposure to phthalates and other endocrine disrupting chemicals found in Defendants’ hair care products.”

Phthalates are a class of chemicals used to make polyvinyl chloride plastic more flexible and as a solvent in a wide range of consumer products, including personal care products like the hair relaxers at issue in this litigation. They are known endocrine disruptors and have been linked to a wide range of chronic diseases, including cancer.

The first hair relaxer lawsuits—the first bodily injury lawsuits that we know of naming phthalates—were filed in October 2022 on the heels of a study published in the Journal of the National Cancer Institute reporting that women who had ever used hair relaxer had an 80 percent higher incidence rate of uterine cancer. Worse still, they found that women who used hair relaxer regularly had a 155 percent higher incidence rate. The study did not examine whether this association is driven by specific chemicals in the hair relaxer products but noted that they frequently contain suspected endocrine disruptors like phthalates, parabens, bisphenols and cyclosiloxanes. This is the first study to report an association between hair relaxer use and uterine cancer, although previous studies have reported associations with breast cancer.

The hair relaxer litigation has more than 95 lawsuits filed to date, with patterns emerging that closely resemble the ongoing talcum powder litigation. In the talcum powder litigation, thousands of plaintiffs allege perineal use of talcum powder caused their ovarian and uterine cancers. Plaintiffs usually state that they started using talcum powder as teenagers and continued to use it daily up until the point of diagnosis.

Black women are more likely to use talcum powder than other women and also have significantly higher rates of uterine cancer. Likewise, hair relaxer is primarily marketed to and used by Black women, often starting from a young age. It is not lost on the plaintiffs’ bar that both talcum powder and hair relaxer products are perceived as playing into sexist and racist beauty norms. Nor is it lost on the hair relaxer plaintiffs that Johnson & Johnson recently made an $8.9 billion offer to settle the talc litigation.

The first lawsuits alleging acetaminophen caused autism spectrum disorders (ASD) were filed in June 2022. Here, the plaintiffs allege acetaminophen use during pregnancy caused the plaintiffs’ ASD, a condition that now affects approximately one in every 36 eight-year-old children in the United States—nearly double the rate from 10 years ago. Acetaminophen is commonly used during pregnancy for pain relief and is available over the counter with no specific warnings from manufacturers and retailers regarding its potentially adverse effect on neurological development. More than 110 lawsuits have been filed thus far, most of which name major retailers including CVS, Walmart, Target, Walgreens and Rite Aid along with Johnson & Johnson, the original patent holder.

Compared to hair relaxer and uterine cancer, the impact of acetaminophen on neurodevelopmental outcomes like ASD and attention deficit hyperactivity disorder (ADHD) is well studied. A consensus statement (https://www.nature.com/articles/s41574-021-00553-7) published in 2021 calling for a precautionary approach to acetaminophen use during pregnancy cites 29 studies of acetaminophen and neurodevelopmental outcomes, 26 of which report a positive association. The consensus statement includes a section that states the case unequivocally: “APAP is an Endocrine Disruptor.” Three studies report a positive association between acetaminophen use during pregnancy and ASD.

A widely cited study published in 2019 in JAMA Psychiatry reported a dose-response relationship between umbilical cord plasma biomarkers of in utero acetaminophen exposure and childhood ASD. Children with moderate exposure had double the ASD risk compared to those with low exposure while children in the highest third had more than triple the risk. Additional research indicates acetaminophen perturbs a variety of hormone-dependent processes implicated in neurodevelopmental disorders.

Autism also features in litigation that erupted in 2021 following a congressional report detailing high levels of heavy metal in baby food. That litigation, however, has generally not fared well for plaintiffs. Consolidation was rejected by the Judicial Panel on Multidistrict Litigation, and many individual actions have been dismissed. In March, for example, a Texas federal judge rendered judgment in favor of Hain Celestial, finding the plaintiffs offered no evidence their son’s ASD was caused by consumption of contaminated baby food.

The plaintiffs’ bar evidently feels more confident about the acetaminophen cases given the science. Defendants also have argued these acetaminophen lawsuits are preempted by federal regulation, an argument that the MDL court has thus far rejected.

As the opening salvos in litigation targeting endocrine disrupting chemicals, the acetaminophen and hair relaxer litigation will prove instructive. To date no court has addressed whether endocrine disruption will be accepted as a mechanism by which a chemical can cause compensable bodily injury. Nor has any court addressed what levels of increased risk will suffice to hold defendants liable for their products.

What has become clear, however, is that mass litigation has changed compared to two of the largest litigations of the 20th century: tobacco and asbestos. In those litigations, the plaintiffs, mostly men, were alleging that inhalation exposure caused lung cancers. Today, the acetaminophen and hair relaxer plaintiffs are women and children trying to get compensation for diseases that are on the rise in the 21st century like autism and reproductive cancers.

With other diseases of modern life on the rise also linked to endocrine disruption, we can expect the precedents made in hair relaxer and acetaminophen litigations to tell us where the plaintiffs’ bar may go in the next round of endocrine disruption litigation.