SACRAMENTO – Pesticides that are the toxic “forever chemicals” known as PFAS are showing up in roughly half of surface water and sediment tests throughout California, a new Environmental Working Group analysis finds, underscoring the need to phase out the use of PFAS pesticides.
The analysis, which examined surface water and sediment test data from the California Department of Pesticide Regulation and the U.S. Geological Survey collected between 2020 and 2024 found that bifenthrin, a PFAS pesticide potentially linked to cancer, was detected in nearly half of all surface water samples and in over half of the sediment samples.
In San Luis Obispo and Stanislaus counties, the chemical was found in over 80% of surface water samples. The data was collected from ten counties across the state, including Santa Barbara and Monterey counties.
“What we are finding in California’s waterways should alarm every Californian, and every American who eats California-grown food,” said Bernadette Del Chiaro, EWG’s senior vice president for California.
“If we’re seeing PFAS pesticides show up this often even in limited surface water and sediment tests, the true scale of this contamination is almost certainly even greater. We need to stop deliberately spraying these toxic chemicals on our crops,” she added.
Millions of Californians are already being exposed to harmful PFAS through pesticide applications on produce grown in the state. EWG’s analysis shows that exposure through surface water and sediment could also be of concern.
More than 2.5 million pounds of PFAS pesticides are applied to California farmland annually. EWG also found frequent detections of these chemicals on produce grown in the state, and that feeds not only California but the rest of the U.S.
Since PFAS never fully break down in the environment, exposure through these two environmental pathways may persist for generations through PFAS’ breakdown products.
Overall sampling data were limited in size and scope, so PFAS contamination from pesticide use is likely more widespread than the data currently suggest. For instance, the data did not include samples from Fresno or Kern Counties, the counties that use the most PFAS pesticides in the state.
“The fact that we are finding potentially carcinogenic chemicals at high rates is a profound public health concern,” said Varun Subramaniam, M.S., EWG science analyst and co-author of the analysis.
“There are data gaps that likely mean PFAS contamination in sediment is underestimated currently. With more frequent and geographically diverse sampling, as well as testing for a wider variety of PFAS, detections would almost certainly rise,” he added.
Breakdown products are concerning
The contamination documented in this analysis may represent only a fraction of the actual PFAS burden in California’s waterways. Many PFAS pesticides transform in the environment into a highly persistent, short-chain form called trifluoroacetic acid, or TFA. Research has linked TFA exposure with reproductive and developmental risks. There are also concerns about TFA’s ability to persist in the environment for an extremely long time.
It remains unknown how long it takes PFAS pesticides to degrade into TFA. It varies according to pesticide types and environmental conditions.
“Since PFAS never fully break down, exposure through surface water and sediment could persist for generations,” said Subramaniam. “In the absence of comprehensive monitoring for TFA and PFAS pesticide breakdown products, we are underestimating how widely these chemicals have spread in the environment and how they are affecting our health.”
This new analysis is a significant step forward in trying to capture the many ways we are exposed to PFAS. And it builds on EWG’s growing efforts to highlight the worrisome broad use of PFAS pesticides in the state that continues unchecked.
A ban would protect people
“We already know that PFAS are toxic chemicals that can harm people in a number of serious ways,” said Susan Little, EWG’s California legislative director. “The state needs to move swiftly to phase out PFAS pesticides for agricultural uses.”
EWG is sponsoring a bill moving through the California State Legislature, AB 1603, which would ban the use, sale and manufacture of PFAS pesticides used on crops statewide by 2035.
“Ending the use of PFAS pesticides would safeguard our food and water systems and prevent PFAS pesticide buildup in the environment,” said Little.
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The Environmental Working Group (EWG) is a nonprofit, non-partisan organization that empowers people to live healthier lives in a healthier environment. Through research, advocacy and unique education tools, EWG drives consumer choice and civic action.
