North Carolina Attorney General Jeff Jackson is urging federal regulators to require public water systems to test for microplastics, saying the government cannot assess the scope of the contamination without collecting nationwide data.
Jackson joined attorneys general from 11 other states and the District of Columbia in asking the U.S. Environmental Protection Agency to add microplastics to its next round of required monitoring for contaminants that do not yet have federal drinking water limits.
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“We know that microplastics are a real public health concern that we need to take seriously,” Jackson said Thursday. “I’m asking the EPA to fix this oversight.”
The attorneys general submitted their letter Monday, the final day of public comment on the EPA’s proposed sixth Unregulated Contaminant Monitoring Rule. The proposal would require certain public water systems to test for 30 contaminants between 2028 and 2030, including several extremely short-chain PFAS, pesticides and industrial chemicals.
Microplastics are not on the proposed monitoring list.
The EPA says there is no validated federal or industrywide method that can reliably measure microplastics in drinking water with the accuracy and quality controls required for nationwide testing. The agency also says it could not develop such a method before a statutory deadline in December.
“If microplastics were included on UCMR 6, the public water systems subject to this rulemaking would be unable to successfully monitor for microplastics,” the EPA wrote in its proposed rule.
The attorneys general say that lack of a standard testing method makes federal action more important, not less. They are asking the EPA to establish a consistent definition of microplastics and develop uniform methods for detecting and measuring them.
If testing every covered water system is not yet feasible, the letter asks the agency to require testing at a smaller selection of systems to begin building a national data set.
Two federal lists, but no drinking water limit
Microplastics are generally defined as plastic particles smaller than 5 millimeters, or less than a quarter-inch. They have been detected in water, food and air, as well as in human blood, lungs and reproductive tissues.
Scientists are still working to determine what those exposures mean for human health. Studies have raised concerns about inflammation, damage to organs and reproductive, cardiovascular and other health effects, but researchers have not established how much exposure through drinking water poses a risk to people. The EPA says more research is needed to understand the potential health effects.
In April, the EPA added microplastics to its draft Contaminant Candidate List, calling the move a “historic action.” That list identifies contaminants the agency may study and consider for future drinking water regulation.
But placement on the candidate list does not require water systems to test for a contaminant, and it does not establish a safety limit.
The Unregulated Contaminant Monitoring Rule serves a different purpose: It produces nationwide data showing where contaminants are found and at what levels. The EPA describes that information as a primary source for decisions about whether federal regulation is warranted.
Past monitoring illustrates both the potential value and the limits of the program. Testing conducted under the third monitoring rule from 2013 to 2015 produced nationwide occurrence data for six PFAS. The EPA later used those results, along with health studies and other information, when deciding to regulate PFOA and PFOS in drinking water.
Those limits were finalized in 2024, more than a decade after the monitoring rule was issued. The current EPA has proposed allowing eligible water systems until 2031 to comply.
Most contaminants placed on the federal candidate and monitoring lists have never received drinking water limits. Public Employees for Environmental Responsibility, an environmental watchdog organization, said its review found that only PFOA and PFOS among more than 200 chemicals or chemical groups placed on candidate lists since 1998 ultimately received federal limits.
“EPA’s Contaminant Candidate List is a regulatory road to nowhere,” PEER Science Policy Director Kyla Bennett said Thursday.
The EPA takes a different view, saying candidate-list placement helps direct research, funding and future regulatory decisions even when it does not immediately result in a drinking water limit.
Jackson’s letter asks the agency to reconsider the omission before finalizing the monitoring rule.
The other signatories are the attorneys general of Delaware, Illinois, Massachusetts, Michigan, Minnesota, New Jersey, New Mexico, New York, Vermont, Virginia and Wisconsin, along with the District of Columbia.