The Environmental Protection Agency has added microplastics to its contaminant candidate list for drinking water for the first time, marking a significant step in federal oversight of the tiny plastic particles found throughout water systems.

The Department of Health and Human Services simultaneously announced a new national program to study the effects of microplastics on human health. The coordinated federal response comes amid growing public concern about potential health risks from these microscopic contaminants.

Microplastics, which are plastic fragments smaller than 5 millimeters, have been detected in drinking water supplies across the country. The particles can originate from various sources including degraded plastic waste, synthetic textiles, and industrial processes.

The EPA's inclusion of microplastics on its contaminant candidate list does not automatically trigger regulation but represents the first formal step in the agency's regulatory process. The list identifies substances that may require future drinking water standards based on potential health risks and occurrence in water systems.

The agency also flagged pharmaceuticals as contaminants of concern on the same list. Both microplastics and pharmaceutical residues have drawn increased attention from health advocates and researchers studying their potential long-term effects on human health.

The HHS study will examine how microplastic exposure affects human health outcomes, providing data that could inform future regulatory decisions by the EPA and other federal agencies.