The Environmental Protection Agency approved several new chemical pesticides last week, sparking backlash from left-wing environmental groups who claim the approvals endanger public health.
The controversy centers on a fundamental disagreement: what counts as a “forever chemical” in the first place.
The EPA approved multiple pesticides — diflufenican, epyrifenacil, and trifludimoxazin — for agricultural use on June 30. The Center for Biological Diversity and Center for Food Safety immediately attacked the approvals, alleging the chemicals contain per- and polyfluoroalkyl substances (PFAS), the so-called “forever chemicals” known for their environmental persistence.
According to the activist groups, these pesticides break down into smaller PFAS chemicals like trifluoroacetic acid (TFA), a water contaminant. The Center for Food Safety claimed epyrifenacil caused liver tumors in male mice. The groups cited past EPA findings of “suggestive evidence” linking trifludimoxazin to cancer.
The controversy hinges on a single technical question: how many fluorinated carbon molecules make a chemical “PFAS”?
The Organization for Economic Cooperation and Development defines chemicals with single-fluorinated-carbon molecules as PFAS. The EPA told Newsweek that diflufenican, epyrifenacil and trifludimoxazin consist of single-fluorinated-carbon molecules under that definition.
The Trump EPA flat-out rejected the OECD standard.
“The Biden EPA’s Office of Pollution Prevention and Toxics defined PFAS as chemicals containing two or more fluorinated carbons,” the agency told the Daily Caller. “That threshold was deliberate, grounded in extensive scientific evidence that single-fluorinated-carbon molecules lack the persistence and bioaccumulation that define genuine PFAS.”
The EPA pointed out that OECD has no regulatory authority over U.S. pesticide approvals — and that OECD itself describes its definition as “a starting and reference point” that “individual users may define their own working scope” around.
Denmark’s Environmental Protection Agency pulled authorization for 23 pesticides in 2025, including diflufenican, partly over alleged TFA contamination. The Pesticide Action Network cited the move as evidence of danger.
The EPA defended its review process as rigorous.
“EPA’s registration decisions applied the same gold-standard review required for every pesticide: comprehensive toxicity testing across species and life stages, evaluation of children’s safety and developmental effects, reproductive and chronic health assessments, environmental fate analysis, and Endangered Species Act evaluations with mitigation where warranted,” the agency said.
“Persistence and bioaccumulation are precisely what EPA’s review examines, and they are exactly what single-fluorinated-carbon compounds lack.”
The Center for Biological Diversity pushed back, insisting chemicals with single fully fluorinated carbons “can stick around for generations or longer.”
“Most PFAS pesticides are expected to eventually degrade into the forever chemical TFA, which could linger in the environment at harmful levels anywhere from months to decades depending on the chemical properties of the individual pesticide,” the group said.
The National Health Institute of Environmental Health Sciences indicated on its website that it considers a chemical PFAS if it has one carbon-fluorine bond — aligning with the OECD definition the Trump EPA rejected.
The U.S. Department of Agriculture did not respond to the Daily Caller’s request for comment.
