Microplastics and nanoplastics are gaining increasing attention among the scientific and regulatory community, and plaintiffs and Attorneys General are taking note. The federal government has not yet established drinking water or other regulatory standards for microplastics. However, recent regulatory actions, and a growing scientific awareness of the potential environmental and health effects resulting from microplastics, indicate movement in that direction. For manufacturers and other businesses that generate products or wastes containing plastic the question is no longer whether—but when—and through which channels, regulation will arrive.
Microplastics are, broadly, small plastic fragments shed throughout the plastic lifecycle both during and after production, use, and disposal that persist and may not naturally degrade in any meaningful timeframe. Nanoplastics are even smaller, often invisible to the naked eye, and have been detected in humans. A 2025 study published in Nature Medicine found that nanoplastic concentrations in brain tissue appeared to increase between 2016 and 2024.
Largely, the regulatory focus in the United States has followed development of the science around microplastics, particularly as sampling and monitoring have produced increased data on the presence of micro- and nanoplastics in surface waters and stormwater. Regulatory attention has shifted from the prohibition of microbeads intentionally added to rinse-off cosmetics, to unintentional releases from sources like tire wear, synthetic textile fibers (fleeces), and particles shed from paints and coatings, among numerous other sources. Analysis suggests that these particles most commonly end up in surface waters, channeled by stormwater and wastewater discharges among other pathways. Stormwater monitoring results, for example, estimate millions to billions of particles are transported in the environment per storm event at individual outfalls.
The United States Environmental Protection Agency (EPA) recently sent a strong signal that it is reviewing microplastics as an emerging contaminant. On April 2, 2026, EPA released its draft Sixth Contaminant Candidate List (CCL 6) under the federal Safe Drinking Water Act and designated microplastics as a priority contaminant group for the first time. While CCL listing does not itself impose enforceable limits, it is a formal step toward the development of potential drinking water standards, which also triggers additional research, monitoring, and data collection. This monitor first, regulate later approach is not uncommon in the United States as the EPA seeks to understand the potential environmental and health effects of a compound before it sets enforceable standards. Following a joint petition by governors of seven states, EPA is also weighing whether to include microplastics in its Unregulated Contaminant Monitoring Rule 6 (UCMR 6), covering 2027–2031.
Congress has introduced bipartisan bills directing federal health agencies to study microplastics’ effects on human health, and the U.S. Department of Health and Human Services has announced a $144 million initiative titled STOMP: Systematic Targeting of MicroPlastics, which is focused on measuring, researching, and the affordably removing microplastics and nanoplastics in the human body. Still, despite this focus by the federal government, today, no single comprehensive federal standard currently governs microplastics.
Yet, the lack of enforceable federal standards has not stopped litigation from arising. Between January 2024 and December 2025, at least 18 microplastics-related federal cases were filed. By comparison, only one lawsuit was filed in the preceding six years. For example, state Attorneys General and private plaintiffs are pursuing greenwashing and false advertising claims under state consumer protection statutes, targeting labels like “natural,” “plastic-free,” and “BPA-free” on products alleged to contain microplastics.
The growing attention on microplastics in both scientific and legal communities will invariably lead to microplastic litigation brought under toxic tort or natural resource damage theories of liability. Environmental citizen suits present a further liability risk. A 2019 Clean Water Act (CWA) citizen suit resulted in a consent decree requiring $50 million in payments to various mitigation projects despite the lack of any specific effluent or water quality standard for microplastics. Another lawsuit lead to a consent decree requiring the payment of $2.5 million in remediation costs, notably, without any explicit permit provision addressing plastic. These cases confirm that even in the absence of plastic-specific standards, plaintiffs are using existing CWA authority over suspended solids as actionable for plastic discharges.
While the future of microplastic regulation and litigation is still unclear, EPA’s CCL 6 and the recent increase in plastics litigation suggest regulatory changes at the State and federal level and litigation headwinds are looming. If PFAS provides any indication of the coming years, businesses across the plastic lifecycle should closely monitor the science and legal landscape and not delay taking measures to manage risks and protect themselves from liability.