EPA Approves Two Pesticide Ingredients Linked to PFAS; California Begins Safety Review

The U.S. Environmental Protection Agency has recently registered two pesticide active ingredients—cyclobutrifluram and isocycloseram—that some scientists and advocates say are linked to PFAS, commonly called "forever chemicals." Cyclobutrifluram is approved for use on romaine lettuce, cotton, soybeans, and turf and ornamental plants. Isocycloseram is approved for a wide range of crops, including brassica vegetables such as cabbage, broccoli and Brussels sprouts.

Both compounds are now under review by California’s Department of Pesticide Regulation (DPR). They cannot be used on crops in California until DPR completes its scientific assessment of the active ingredients and full product formulations—a process that can take months or several years.

Why scientists and advocates are concerned

PFAS (per- and polyfluoroalkyl substances) are a large family of human-made chemicals used in many consumer and industrial products, from nonstick cookware and firefighting foams to some pesticides. PFAS are notable for extremely strong carbon–fluorine bonds that make many of them highly persistent in the environment—hence the label "forever chemicals." Researchers have linked PFAS exposure to reduced fertility, higher risks for certain cancers, and weakened immune responses.

The two newly approved pesticides each contain at least one carbon atom fully bound to fluorine atoms. The EPA’s formal definition of PFAS typically requires two or more fluorinated carbons, but some scientists and regulatory bodies use a broader definition that includes chemicals with a single fully fluorinated carbon. "There is not a universally accepted definition for PFAS," said Clare Pace, an assistant project scientist at UC Berkeley.

Environmental advocates warn that adding these ingredients could increase the number of fluorinated pesticide compounds used in U.S. agriculture. An analysis by the Environmental Working Group estimated an average of about 2.5 million pounds of PFAS-related pesticide ingredients were applied across California; Fresno County alone reportedly recorded more than 2 million pounds applied from 2018 to 2023, according to California DPR data.

Breakdown products and water contamination risks

Scientists also worry about environmental transformation products. Both isocycloseram and cyclobutrifluram can degrade into trifluoroacetic acid (TFA), an ultrashort-chain fluorinated compound that dissolves readily in water and is difficult to remove from aquatic systems. "This means that concentrations of TFA in groundwater, surface water, and oceans will continue to increase, with unknown consequences," said Clare Pace.

Jane Williams, executive director of California Communities Against Toxics, emphasized that fluorinated chemicals can bioaccumulate and move up the food chain: "Spraying fluorinated chemicals on crops is such a bad idea, not just for the environment but for human health. These chemicals bioconcentrate up the food chain and unfortunately humans are at the very top of the food chain."

Regulatory review and industry response

California’s DPR said its review assesses both active ingredients and full product formulations to understand environmental persistence, breakdown products, and chemical-specific toxicity. "The review includes evaluating how long the chemicals remain in the environment and how they break down, and it considers potential risks to human health and the environment," said Amy MacPherson, DPR deputy director of outreach and communications.

The review timeline varies. While some new ingredient applications have taken several years to complete, observers expect decisions could occur more quickly or slowly depending on the science and public input. "I would expect these to get approved in (California) within the year," said Nathan Donley, environmental health science director at the Center for Biological Diversity, though others note uncertainty.

Agricultural groups stress the need for new pest-control options. The Western Growers Association said growers have faced increasing pest pressures and resistance problems and need additional tools to protect crops and livelihoods.

What to watch next

California’s DPR will continue its scientific evaluation and may request additional data or impose use restrictions if it allows these products. Key issues to watch include whether DPR deems the compounds PFAS under its regulatory definitions, whether it identifies significant risks from degradation products like TFA, and whether mitigations (such as buffer zones or use limits) are imposed to reduce environmental and human-health exposures.

"To think that we are devolving into that place again is frightening to see," said Nathan Donley, referring to past controversies over persistent pesticides such as DDT.

As the state review proceeds, farmers, scientists, advocates and regulators will be evaluating trade-offs between managing crop pests and limiting the potential long-term environmental and public-health impacts associated with fluorinated pesticide chemistry.