Microplastics – The Future of Toxic Tort Litigation?

Introduction

Microplastics are increasingly gaining attention in the scientific community for their potential to accumulate in human beings and the environment. The ubiquitous use of microplastics and their pervasive presence in living beings and the environment have strong parallels to allegations about certain per- and polyfluoroalkyl substances (PFAS), or “forever chemicals,” that have spawned waves of litigation — including toxic tort litigation — in recent years. An initial wave of microplastics litigation has already been filed, but cases to date have focused on a relatively discrete set of defendants, emphasizing consumer protection and “greenwashing” theories. Given the claimed similarities to PFAS and mounting public attention, a new wave of microplastics litigation brought under toxic tort theories seems both likely and imminent.

Parallels to PFAS

Over the past decade, the plaintiffs’ bar has adopted new and expansive theories of liability premised on substances ubiquitous in modern society. PFAS chemicals provide one of the clearest examples. Known for their stain-resistant and fire-retardant properties, certain PFAS chemicals were in widespread use for decades and have been found in a variety of products, including stain-resistant fabrics, cosmetics, cookware, and firefighting foams used by the U.S. military. But once released into the environment, certain PFAS chemicals persist — not easily broken down — and may accumulate in the bodies of humans and wildlife.

Following the discovery of PFAS chemicals in public water supplies, PFAS litigation snowballed. In the initial wave, claims were brought by individuals and classes of individuals alleging health effects from PFAS-contaminated drinking water and harm to the value of their properties, and seeking medical monitoring. Alleged health effects ranged from kidney and testicular cancers to hypothyroidism and high cholesterol. As the litigations progressed, PFAS gained the attention of both regulators and scientists, and the body of scientific literature on PFAS chemicals and their effects grew. Individuals’ claims were later followed by claims of local water districts and municipalities seeking to recover increased costs of treating water supplies to meet increasingly stringent state and federal standards for PFAS in drinking water. And a series of consumer fraud and “greenwashing” lawsuits were filed as well, claiming that manufacturers who advertised products as “safe,” “natural,” or “sustainable,” but who used PFAS chemicals in their manufacturing processes, were deceiving the public and misrepresenting their products as “greener” than they actually were.

While the filing of new PFAS cases has slowed, the scientific and legal communities’ attention has turned to microplastics, another material understood to be pervasive in virtually all aspects of modern life. These plastic particles — 5 mm or less in size — are thought to be released from an array of everyday consumer products, degradation of larger plastic products, and industrial processes. Studies point to plastic water bottles, food containers, tea bags, chewing gum, infant feeding bottles, cookware (e.g., plastic cutting boards), medical supplies (e.g., IV bags), medical devices, tires, cosmetics, and paints as potential sources of microplastics. Microplastics have been detected in almost every environment, including oceans, lakes, soil, and air. And it has been suggested that microplastics are in the blood of virtually every American. As awareness of the widespread presence of microplastics has grown, studies on the health effects of microplastics in the human body and the environment have ballooned.

Attention on Health and Environmental Effects of Microplastics

In recent years, there has been an outpouring of scientific literature attempting to identify the impacts of microplastics’ presence in human beings and the environment. Researchers claim links between microplastics and a range of human health effects, including increased cardiovascular risk, hormonal interference, cancers (e.g., colorectal, lung), gut microbiome disruption, systemic inflammation, mitochondrial dysfunction, antibiotic resistance, and harms to reproductive, digestive, and respiratory health. Studies argue that microplastics have the potential to accumulate in various organs of the body, including the liver, kidneys, gastrointestinal tract, and brain. A study from earlier this year suggested that the average person may have roughly a spoonful of microplastics in their brain alone. Another claimed a “significant association” between marine microplastic levels and the prevalence of cognitive disabilities in U.S. coastal counties, and a third paper theorized a link between microplastics and dementia. Researchers examining how microplastics in the environment impact ecological systems and food supplies have pointed to possible interruption of photosynthesis in plants and negative health effects in fish, birds, and other biota resulting from the ingestion and inhalation of plastics.

Limited Existing Microplastics Regulation

As in the early days of PFAS litigation, regulation of microplastics has been relatively limited, but that is starting to change. A number of states have adopted measures aimed at reducing plastics waste or improving recycling programs. California has adopted criteria for testing for and reporting microplastics levels in drinking water. At the federal level, the Microbead-Free Waters Act of 2015, which banned microbeads in rinse-off cosmetics, has been the primary microplastics legislation.

However, the federal government has recently turned its attention toward studying microplastics and their impact. This summer, two bills were introduced in the House calling for studies on the human health impacts of exposure to microplastics (the Microplastics Safety Act and the Plastic Health Research Act). Federal agencies such as the U.S. Food and Drug Administration (FDA), the U.S. Environmental Protection Agency (EPA), and the National Oceanic and Atmospheric Administration acknowledge existing research concerning the impacts of microplastics on human health and the environment, but suggest that further study is needed. FDA states on its website that “[c]urrent scientific evidence does not demonstrate that levels of microplastics or nanoplastics detected in foods pose a risk to human health.” EPA recognizes that microplastics have “been found in human livers, kidneys, and placentas,” but concludes that “[m]ore research is needed to better understand the potential human health impact of microplastics.” It was reported this summer that EPA is considering a November 2024 petition from 175 environmental groups calling for microplastics to be included on EPA’s Sixth Unregulated Contaminant Monitoring Rule (UCMR 6); inclusion on UCMR 6 would make microplastics in drinking water subject to monitoring and, potentially, future regulation. On September 9, 2025, the Trump administration’s Make America Healthy Again Commission released its “Make Our Children Healthy Again Strategy Report,” which — among other things — provides that the U.S. Department of Health and Human Services, along with the National Institutes of Health and EPA, will “complete an evaluation of the risks and exposures of microplastics and synthetics, including in common products such as textiles.”

Existing Microplastics Litigation

Over the past five years, litigation related to microplastics has focused on a relatively discrete set of major plastics producers and users. In most of these cases, environmental advocacy groups, state attorneys general, and private individuals have relied on consumer protection theories (e.g., consumer fraud, false advertising, deceptive practices, unfair competition) and “greenwashing” theories, while also asserting nuisance claims (and, in at least one case, antitrust claims). Plaintiffs in those cases argue that major plastics manufacturers such as Exxon — along with major food, beverage, and consumer product companies that use plastics and plastics packaging — misrepresented the recyclability of plastics, resulting in increased plastics use among consumers and creating a “plastics crisis.” These cases have emphasized the alleged harms caused by plastics pollution in the environment, with the release of microplastics as one of those alleged harms.

Along similar lines, the State of New York and the City of Baltimore filed cases against major beverage companies, including PepsiCo and Coca-Cola, claiming that littering of the companies’ packaging caused contamination and that the companies failed to warn of the risks of pollution and harm caused by plastics. In addition to consumer fraud theories, plaintiffs in those cases assert nuisance and product liability theories and alleged violations of littering laws.

Over the past two years, a series of cases have been filed that target manufacturers of packaging and containers that allegedly leach microplastics into beverages or food. Multiple individual and class action lawsuits have been filed against suppliers of bottled water on consumer fraud and greenwashing theories, claiming that the bottles contain dangerous levels of microplastics while being falsely marketed as “natural.” In June 2024, two putative class actions were filed against manufacturers of baby bottles, claiming that the companies failed to warn consumers that the bottles leached microplastics when heated and had misled consumers into thinking the bottles were safe by using “BPA-free” labels. In May 2025, a putative class action was filed against S.C. Johnson & Son, Inc., alleging that the company’s Ziploc products were deceptively marketed as “microwave safe” and “for freezer use,” while failing to warn that microplastics could leach from the containers when heated or frozen. In those cases, plaintiffs alleged violations of consumer protection laws and unjust enrichment. Along similar lines, in June 2025, a putative class action was filed against Water Wipes (USA) Inc., claiming that the defendant falsely marketed its baby wipes as “plastic-free” and “pure,” when they allegedly contain microplastics.

Anticipated Toxic Tort Litigation

Given the mounting attention on microplastics in the scientific and legal communities, it seems to be only a matter of time until microplastics litigation is brought under toxic tort theories. If PFAS is any indication, one would anticipate — for example — lawsuits brought by individuals or classes of individuals whose drinking water has been impacted by microplastics, alleging a host of potential health conditions and/or seeking medical monitoring. Likewise, one might expect lawsuits by property owners claiming that their property values have decreased, or that their enjoyment of those properties has been negatively impacted, due to the detection of microplastics. If the regulation of and testing for microplastics grow, there may also be a rise in claims by local water districts or governments seeking the costs of such testing and remedial efforts. And it is possible that governmental plaintiffs could pursue even more far-reaching theories of liability and damages, such as broad claims of public nuisance and claims for the lost value of natural resources impacted by microplastics.

Plaintiffs will face significant hurdles in bringing microplastics litigation on these theories. For example, at this point, there is no scientific evidence that the presence of microplastics in fact causes any impact on human health and the environment. In addition, methods for detecting, analyzing, and quantifying microplastics in the human body and the environment are relatively new and not well-established, complicating the admissibility of expert opinions that rely on such methods. Further, connecting the microplastic in a body to a particular source will be extremely difficult, given the multitude of potential sources. However, as we have seen repeatedly, plaintiffs firms may not be deterred by a lack of information or evidence of causality, and may focus on communities or geographic areas where microplastic concentrations in the environment or in humans are believed to be particularly elevated.

Takeaways

While the future of microplastics litigation is still taking shape, companies facing potential exposure from their manufacturing or use of plastics in their products or processes should closely monitor the science and legal landscape going forward. Regulation of microplastics is likely to expand at both the state and federal levels, and the case law and theories for liability in existing plastics litigation continue to develop. Consulting with counsel experienced in emerging contaminant regulations and large-scale toxic tort litigations can allow companies to assess exposure and manage risk related to microplastics. For questions or additional information, please reach out to the authors of this Advisory or your Arnold & Porter contact.

© Arnold & Porter Kaye Scholer LLP 2025 All Rights Reserved. This Advisory is intended to be a general summary of the law and does not constitute legal advice. You should consult with counsel to determine applicable legal requirements in a specific fact situation.