Members of Congress have formally asked the U.S. Government Accountability Office to review how the Environmental Protection Agency assesses the presence and risk of microplastics, according to a request tracked by the legal news service JD Supra.

The referral sends a specific question to GAO's examiners: what has EPA actually done, in documented programs and filings, to determine where microplastics occur and at what levels they threaten health or the environment. GAO accepts such requests from Congress and typically returns a report with findings and recommendations within months, though the office has not yet published a delivery date for this review.

Why a GAO review reaches the materials stream

Microplastics enter waste and recycling chains at several points — fragmenting plastic in landfills, shredding and washing at recovery facilities, discharging through wastewater effluent and compost applications. Any EPA determination that these particles pose a measurable risk would trigger monitoring obligations and, eventually, treatment standards for facilities that handle plastic-rich streams.

At stake for operators is whether microplastics become a regulated contaminant with numeric thresholds, the way PFAS moved from research agenda to enforceable limits over roughly a decade. A GAO report that finds EPA's assessment work incomplete or uncoordinated usually precedes congressional pressure to fund and staff it.

What does the review change for EPA?

In the near term, nothing binding. GAO audits do not create rules. What they do is establish, on the record, which EPA offices have assessed microplastics, which methods they used and where the gaps sit.

The request, as reported by JD Supra, frames the inquiry around two axes: presence and risk. That distinction matters for the agency's obligations. Documenting presence — detection methods, sampling protocols, occurrence data — falls within EPA's research arm. Establishing risk requires toxicological exposure studies that take years and dedicated appropriations.

If GAO finds EPA has treated microplastics as a dispersed research topic rather than a managed program, the likely recommendation is a coordinated strategy with milestones. Congress then decides whether to mandate one through authorization language.

The precedent GAO will likely follow

The accountability office has built a record on emerging-contaminant reviews. Its past work on PFAS documented fragmented federal monitoring before lawmakers consolidated EPA's response into a national roadmap with statutory deadlines. Microplastics now follow a similar path: congressional attention first, GAO inventory second, strategy mandate third.

The timeline from referral to published report typically runs six months to a year, depending on scope. Until GAO delivers, the operative facts are these: a congressional request exists, EPA's microplastics assessment practices are the subject, and no federal numeric standard for microplastics in water, air or solid waste has yet been issued.

What to watch next

The milestone that decides what follows is the GAO report's publication date and its recommendations — specifically whether it calls for a formal EPA microplastics strategy with deadlines. Until that document appears, facilities and jurisdictions handling plastic-heavy streams face no new federal obligations, but should track the review as the leading indicator of standards to come.