A first-of-its-kind analysis has identified Pfas pesticide residues on 37% of conventional California produce, with peaches, strawberries and grapes almost always found to be contaminated with the toxic “forever chemicals”.

The analysis coincided with the introduction of California legislation that would by 2035 fully ban Pfas from being used as active ingredients in pesticides, and require warning labels and other restrictions in the meantime.

The Environmental Working Group (EWG) non-profit conducted the analysis of California department of pesticide regulation residue testing records. It found about 90% of peaches, plums and nectarines contained Pfas residues, while 80% of strawberries and grapes showed them. Those levels are especially alarming because children commonly eat fruits like grapes and strawberries, and children are most at risk from the chemicals’ toxic effects, said Bernadette Del Chiaro, senior vice-president of EWG’s California operations.

“Most consumers don’t expect to find Pfas ‘forever chemicals’ on their strawberries – I think this information is shocking to most people,” Del Chiaro added.

Pfas are a class of at least 16,000 compounds typically used to make common products that resist water, stains and heat. They are called “forever chemicals” because they do not naturally break down and accumulate, and are linked to cancer, kidney disease, liver problems, immune disorders, birth defects and other serious health problems.

Advocates began sounding the alarm over Pfas in pesticides in 2023. The Environmental Protection Agency (EPA) under Joe Biden attempted to discredit the author of one study that identified the chemicals in pesticides, while, under Donald Trump, the EPA has increased the number of Pfas proposed for use on crops.

At least 60% of active ingredients federally approved to be used in common pesticides in recent years fit the most widely accepted definition of Pfas, a 2023 analysis of EPA data found. The chemicals are added as an active ingredient to crop pesticides to kill weeds or pests.

EWG analyzed records for 930 samples across 78 types of non-organic, California-grown fruits and vegetables.

It found 348 samples, or 37%, showed Pfas residues. About 40 individual types of fruits and vegetables contained residues, meaning at least half of all produce varieties were treated with Pfas pesticides.

The chemicals are not just a problem for food – they persist in the environment and pollute drinking water supplies. The city of Fresno, in an agricultural region, recently sued Pfas makers over pollution of groundwater, which exceeded federal limits by 600%. The contamination impacts more than 120,000 homes.

A previous EWG analysis of state records found 2.5m pounds of Pfas are spread on California cropland annually.

“Here’s a chemical that we in society at large are trying to get out of our environment and drinking water … and yet here on the flip side there is a regulatory agency permitting its use on crops,” Del Chiaro said.

The health impacts are largely unclear because Pfas pesticides are a relatively new issue to researchers, and little data beyond that produced by industry exists.

“We know that Pfas can be dangerous, we know that pesticides can be dangerous, but we don’t really know enough about this new understudied exposure route,” said Varun Subramaniam, a report co-author and analyst with EWG.

He noted that the produce may contain more than one kind of Pfas pesticide. Ten products are approved for use on strawberries, but the regulatory system only accounts for the risks of one pesticide, even though that is not how people are typically exposed.

“We know people are exposed to cocktails of pesticides and literature shows that these combinations can often be more harmful, so that’s a blind spot for the EPA at the moment,” Subramaniam said.

The proposed legislation in California would ban the use of Pfas as an active ingredient in pesticides by 2035. By 2030, the 23 Pfas pesticides that are already banned by the European Union, but still used in the US, would also be banned in California. The bill would also place a moratorium on approvals of new Pfas pesticides, and require labels to warn farmers, who advocates say often do not know their pesticides contain Pfas.

The pesticide industry will almost certainly mount a ferocious campaign against the legislation. Maine and Minnesota have already passed similar bans, making it more likely to pass in California. Though the state often leads in new environmental protections, Gavin Newsom, California’s governor and a frontrunning potential candidate for the 2028 Democratic nomination for president, is susceptible to industry influence, especially on Pfas legislation.

In December, the California legislature by a wide margin passed a bill that would have banned Pfas in cookware and other everyday products, but Newsom vetoed it after receiving pressure from the cookware industry and celebrity chefs. He has so far not said anything about the pesticide legislation.

The bill’s author, California assemblymember Nick Schultz, said in a statement that he doesn’t want his kids “eating strawberries contaminated with chemicals that will stay in their bodies for decades”.

“We are providing a clear, responsible road map for our farmers to transition away from these persistent chemicals while re-establishing California as a global leader in food safety,” Schultz added.