U.S. regulators on Thursday issued a new warning over potential contaminants in drinking water, as the Environmental Protection Agency (EPA) moved to formally flag microplastics as a growing public health concern that could eventually be subject to nationwide regulation.
The EPA announced it has added microplastics to its draft Sixth Contaminant Candidate List, elevating the tiny plastic particles as a priority group for federal research and monitoring under the Safe Drinking Water Act, a press release from Beyond Plastics said on Thursday. The move launches a yearslong process that could lead to enforceable drinking water standards, as studies increasingly detect microplastics in human organs, blood and breast milk.
The EPA revealed details about the move in a live announcement on Thursday afternoon. During the event, Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. said there is scientific evidence that exposure to microplastics begins before birth.
"This is not a rare exposure, this is baseline," Kennedy told reporters.
He went on to add that there is concern that microplastics can drive inflammation, tumor growth and cardiovascular issues. Diseased tissues showed higher concentrations of microplastics than healthy ones, Kennedy said.
What Are Microplastics?
Microplastics—tiny plastic particles measuring 5 millimeters or less—will now be prioritized for research, monitoring and potential regulation nationwide. The draft list has been opened to a 60-day public comment period, with a final version expected by November 17.
Environmental advocates praised the decision as an overdue acknowledgment of an emerging threat. Beyond Plastics, a national advocacy group focused on reducing plastic pollution, called the EPA’s move an “important first step” while urging the agency to act swiftly.
“The U.S. Environmental Protection Agency has taken an important first step to regulate microplastics in drinking water,” Judith Enck, president of Beyond Plastics and former EPA regional administrator, said in a press release. “I applaud this decision by the EPA and urge the agency to move rapidly to not only regulate microplastics in drinking water but to also prevent microplastics from entering our water supplies.”
Microplastics and their even smaller counterparts, nanoplastics—defined as particles measuring 1 micrometer or less—have drawn increasing scrutiny from scientists in recent years. Research has detected the particles not only in drinking water but also in food, air and a growing list of human tissues and fluids.
Studies have identified microplastics in human blood, lungs, kidneys, bone marrow, placentas, breast milk and reproductive organs, according to Beyond Plastics. Some findings suggest that the smallest particles are capable of crossing the blood-brain barrier, raising questions over potential neurological impacts.
Despite the mounting evidence of human exposure, scientists say key questions remain unanswered, including how microplastics affect long-term health and what levels, if any, can be considered safe. Federal officials have framed the EPA’s latest action as an effort to close those knowledge gaps while building the foundation for future regulation.
Public water utilities and state regulators are expected to closely follow the EPA’s next steps, as new monitoring requirements could impose additional costs and technical challenges. Advocates, however, argue that early action is essential to protect public health and reduce contamination at its source.