HHS and EPA Launch $144 Million Program to Study Microplastics in Human Body

For the first time, the federal government moved Thursday to systematically measure microplastics inside the human body, committing $144 million to a new research program and formally elevating the particles as a drinking water priority in a coordinated push that scientists say could reshape environmental health policy for years.

HHS Secretary Robert F. Kennedy Jr. and EPA Administrator Lee Zeldin announced the actions at EPA headquarters in Washington, D.C. The Advanced Research Projects Agency for Health, the high-risk, high-reward research arm of HHS, launched STOMP (Systematic Targeting Of MicroPlastics), while the EPA separately released its draft Sixth Contaminant Candidate List, which for the first time includes microplastics and pharmaceuticals among priority contaminants that may warrant future drinking water regulation.

"We are not dealing with a distant or theoretical risk. We are dealing with a measurable, growing presence inside the human body," Kennedy said at the briefing, citing research showing microplastics in human organs, blood and the placenta.

STOMP is structured in two phases, led by program managers Drs. Ileana Hancu and Shannon Greene. Phase one focuses on measurement and mechanism: developing validated tools for detecting and quantifying microplastics and nanoplastics in human tissues and fluids, and mapping the pathways by which they accumulate across organ systems. Phase two turns to removal, with researchers tasked with developing affordable, scalable technologies to reduce the body's microplastic burden. The program explicitly prioritizes vulnerable populations, including pregnant people, children and workers with high occupational exposure.

"A key first step is to measure microplastics accurately and understand how they reach different organ systems," Hancu said. "So we must establish a solid, shared foundation for precise measurement and mapping."

Alicia Jackson, ARPA-H's director, captured the gap STOMP is designed to close: "Microplastics are in every organ we look at, in ourselves and in our children. But we don't know which ones are harmful or how to remove them. The field is working in the dark. STOMP is turning on the lights."

The EPA's CCL action carries distinct but complementary weight. Under the Safe Drinking Water Act, the agency is required to update the Contaminant Candidate List every five years; CCL 6 is the sixth iteration. Inclusion on the list does not impose regulations, but it formally designates microplastics a research and monitoring priority, opening a statutory pathway that could eventually require utilities to test for the particles and spur investment in water treatment infrastructure. The draft CCL 6 also covers per- and polyfluoroalkyl substances, disinfection byproducts, 75 individual chemicals and nine microbes.

"For too long, Americans have vocalized concerns about plastics and pharmaceuticals in their drinking water. That ends today," Zeldin said.

What remains unproven matters as much as what was announced. Scientists have detected microplastics in human lungs, arterial plaques and brain tissue, and animal studies show biological effects. Direct evidence linking specific human health outcomes to microplastic exposure at population scale is still limited, and the absence of standardized measurement tools has made large-scale epidemiological research difficult to conduct. STOMP's phase-one work is explicitly designed to build that evidentiary foundation before drawing clinical conclusions.

Judith Enck, president of the advocacy group Beyond Plastics, called the CCL inclusion "an important first step," a phrase that captures both the significance of the designation and its distance from enforceable standards. If STOMP's first phase produces validated biomarker data confirming harm, the CCL designation gives the EPA the statutory footing to pursue maximum contaminant level rulemaking, a process requiring public comment periods and feasibility analysis before any utility testing mandates could take effect.