California Nurses for Environmental Health and Justice is urging the EPA to include microplastics and nanoplastics in the final Sixth Unregulated Contaminant Monitoring Rule (UCMR 6). Growing evidence indicates that these particles, and plastic associated chemicals detected in water, including PFAS, phthalates, bisphenols, and flame retardants—may pose significant risks to human health. National monitoring is an essential first step toward understanding exposure, protecting drinking water, and preventing harm.
Public Comment Supporting Inclusion of Microplastics in UCMR 6
On behalf of California Nurses for Environmental Health and Justice, we urge the U.S. Environmental Protection Agency (EPA) to include microplastics and nanoplastics in the final Sixth Unregulated Contaminant Monitoring Rule (UCMR 6).
As nurses and public health professionals, we know that preventing disease requires identifying harmful exposures before they result in illness. Because drinking water is a universal exposure, determining the extent of microplastic contamination is an essential public health responsibility.
Microplastics have been detected in source water, treated tap water, and bottled water. They have also been found in human blood, lungs, placentas, and other tissues, showing that these particles can enter and persist in the body. Laboratory and human evidence links microplastic and nanoplastic exposure with inflammation, oxidative stress, immune disruption, and cellular injury. Nanoplastics are especially concerning because their small size may allow them to cross biological barriers and reach the bloodstream and organs (Landrigan et al., 2023; WHO, 2022).
The health concern extends beyond the particles themselves. Plastics contain thousands of chemical additives, including phthalates, bisphenols, PFAS, and flame retardants. Many are known endocrine disruptors, reproductive or developmental toxicants, neurotoxicants, or carcinogens. These chemicals are not always tightly bound to plastic and can leach into water, food, and the environment. Microplastics may therefore expose people both to the physical particles and to hazardous chemicals carried in or on them. Human studies associate several widely used plastic chemicals with reproductive, developmental, metabolic, cardiovascular, and cancer-related harms (Landrigan et al., 2023).
Human research supports precaution. In a prospective observational study of patients undergoing carotid endarterectomy, microplastics or nanoplastics were found in the arterial plaques of 150 of 257 patients who completed follow-up. Patients with particles in their plaques had approximately 4.5 times the risk of heart attack, stroke, or death from any cause during about 34 months of follow-up (Marfella et al., 2024).
The absence of complete information about long-term effects is precisely why monitoring is needed. National data would help public health agencies measure exposure, identify disproportionately affected communities, compare water sources, evaluate treatment systems, and guide health protections.
The proposed UCMR 6 would require participating water systems to monitor 30 chemical contaminants between 2028 and 2030 but excludes microplastics (EPA, 2026a). At the same time, EPA included microplastics as a contaminant group on its draft Contaminant Candidate List 6, recognizing that they may occur in public water systems and may warrant regulation under the Safe Drinking Water Act (EPA, 2026b). Their exclusion from UCMR 6 creates a troubling gap between recognizing a threat and collecting the data needed to evaluate it.
Although EPA has cited the lack of a finalized federal analytical method, California has adopted standardized methods for testing microplastics in drinking water and developed a framework for monitoring and public reporting (California State Water Resources Control Board, 2022). EPA can build on this work while validating and improving methods for national use.
Waiting for a perfect method will delay urgently needed information. Scientific uncertainty should prompt monitoring, not prevent it. Monitoring provides the evidence needed to measure exposure, investigate risks, improve water treatment, and determine whether regulation is warranted.
From a nursing and public health perspective, the responsible course is clear: measure the exposure, publicly report the findings, and use the evidence to protect health. We strongly urge EPA to include microplastics and nanoplastics in the final UCMR 6.
Respectfully submitted,
California Nurses for Environmental Health and Justice
References
California State Water Resources Control Board. (2022). Microplastics in drinking water. https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/microplastics.html
Landrigan, P. J., et al. (2023). The Minderoo-Monaco Commission on Plastics and Human Health. Annals of Global Health. https://annalsofglobalhealth.org/articles/10.5334/aogh.4056
Marfella, R., et al. (2024). Microplastics and Nanoplastics in Atheromas and Cardiovascular Events. New England Journal of Medicine. https://www.nejm.org/doi/full/10.1056/NEJMoa2309822
U.S. Environmental Protection Agency. (2026a). Proposed Sixth Unregulated Contaminant Monitoring Rule. https://www.epa.gov/dwucmr/proposed-sixth-unregulated-contaminant-monitoring-rule
U.S. Environmental Protection Agency. (2026b). Draft Contaminant Candidate List 6 - CCL 6. https://www.epa.gov/ccl/draft-contaminant-candidate-list-6-ccl-6
