A fight over three words — "per- and polyfluoroalkyl" — is now shaping what gets sprayed on American crops.
The approvals
Since early 2025 the Environmental Protection Agency has registered five pesticides that environmental groups and many independent scientists describe as PFAS. On June 30 the agency posted registration documents for diflufenican and epyrifenacil, herbicides cleared for corn and soybeans, and a day later registered trifludimoxazin, approved for wheat, oranges, apples and almonds, the Center for Biological Diversity said. Two earlier registrations, the insecticide isocycloseram and the fungicide cyclobutrifluram, were finalized in November 2025. By comparison, the Biden administration registered one such pesticide over four years.
Why scientists are alarmed
PFAS are a family of thousands of synthetic chemicals built around the carbon-fluorine bond, one of the strongest in chemistry. Because they resist breaking down, they accumulate in water, soil and the human body — nearly all Americans carry detectable PFAS in their blood — and the EPA has linked certain PFAS to cancers, thyroid disease and reproductive harm.
Under a definition the Organization for Economic Cooperation and Development published in 2021, any chemical with at least one fully fluorinated carbon is a PFAS — a threshold all five pesticides meet. That standard has been endorsed by more than 150 researchers and adopted by about two dozen states, Chemical & Engineering News reported. Critics also note that several of the compounds break down into trifluoroacetic acid, a highly persistent PFAS. Advocacy and farmworker groups have filed suit over two of the approvals. "EPA itself acknowledges that the PFAS pesticide isocycloseram presents significant human health and environmental risks, yet the agency swept those risks under the rug," said Sharmeen Morrison, an Earthjustice attorney.
The EPA's defense
The EPA rejects the premise. In a November fact-check, the agency pointed to its own regulatory definition, finalized in 2023 under the Biden administration, which requires two or more fully fluorinated carbons for a chemical to count as PFAS. Single-fluorinated compounds, the agency says, "lack the persistence and bioaccumulation properties that are commonly associated with forever chemicals," and it maintains they "are not PFAS" and "do not pose any risks of concern when used as labeled," according to the EPA. The agency says every pesticide undergoes rigorous review for toxicity and children's health. The pesticide industry agrees: CropLife America's Manojit Basu credited the EPA's "scientifically rigorous and transparent evaluation process" with giving farmers essential tools.
A genuine dispute
The disagreement is real, not merely rhetorical. Chemists have long debated where to draw the line, and longer fluorinated chains do show stronger persistence than single-carbon ones; single-fluorinated pesticides have been registered for years in Europe, Canada and Australia. But critics counter that the EPA's approval process, built to gauge acute and medium-term toxicity, is ill-suited to compounds that may linger for decades and combine with PFAS already in the environment. In Congress, a bill introduced in December would settle the matter by law, defining PFAS as any chemical with at least one fully fluorinated carbon.
The stakes are concrete for California: diflufenican and epyrifenacil are now cleared for the corn and soy at the base of the food supply, and trifludimoxazin for the citrus and tree fruit grown across the San Joaquin Valley.
