A new bill introduced in California’s legislature aims to phase out the use of PFAS pesticides, a class of persistent synthetic chemicals increasingly associated with environmental contamination and human health risks.

The proposal follows recent testing that detected these substances in a substantial portion of conventionally grown fruits and vegetables across the state.

The legislation, Assembly Bill 1603 (AB 1603), would establish a timeline to eliminate PFAS pesticides from California agriculture, with interim measures focused on transparency and regulatory oversight.

The move positions California to align more closely with jurisdictions that have already imposed restrictions on these chemicals.

Evidence of contamination drives policy push

Recent analyses of state data indicate that PFAS pesticide residues are present in a notable share of California-grown produce.

Testing of 930 non-organic fruit and vegetable samples found detectable levels in approximately 37% of cases. More than half of the produce types examined showed at least some contamination.

Separate laboratory results highlighted particularly high detection rates in stone fruits, with the majority of tested peaches, nectarines and plums containing measurable residues.

PFAS – short for per- and polyfluoroalkyl substances – are widely used in industrial applications due to their chemical stability.

That same stability, however, means they persist in the environment and accumulate in living organisms. Their resistance to degradation has earned them the label “forever chemicals.”

What AB 1603 proposes

The bill outlines a phased approach to restricting PFAS pesticides in California.

Key provisions include:

• 2027: Suspension of new state approvals for PFAS-based pesticides
• 2027: Mandatory public disclosure and reporting on their use
• 2030: Ban on 23 PFAS pesticide active ingredients already prohibited in the European Union
• 2035: Full prohibition on the use, sale and manufacture of all PFAS pesticides

The measure has been referred to the Assembly Committee on Environmental Safety and Toxic Materials and is expected to be reviewed in the coming weeks.

Scale of PFAS pesticide use in California

PFAS pesticides represent a relatively small proportion of registered agricultural chemicals but account for a disproportionate share of detected residues. Of roughly 70 such pesticides registered at the federal level, more than 50 are approved for use in California.

While these substances account for about 5% of the active pesticide ingredients registered in the state, they are responsible for an estimated 15% of residues found on produce.

Usage data suggests widespread application. Between 2018 and 2023, California farmers applied roughly 15 million pounds of PFAS pesticides, averaging about 2.5 million pounds annually across all counties.

The highest usage levels have been reported in major agricultural regions, including Fresno, Kern, San Joaquin and Imperial counties.

These chemicals are commonly applied to high-value crops such as almonds, pistachios, wine grapes and tomatoes.

Environmental persistence and byproducts

One of the central concerns surrounding PFAS pesticides is their environmental durability. The carbon-fluorine bond that defines these compounds is among the strongest in organic chemistry, making them highly resistant to breakdown.

Over time, PFAS can degrade into secondary compounds, including trifluoroacetic acid (TFA). This byproduct is increasingly detected in water systems, wildlife and human populations.

Estimates suggest that pesticide-related PFAS use in California may generate hundreds of thousands of pounds of TFA annually.

Emerging research links TFA exposure to potential reproductive and immunological effects, though the full scope of its impact remains under investigation.

Gaps in toxicity data

Regulatory scrutiny has intensified partly due to incomplete toxicological data for many PFAS pesticides. A recent analysis by federal regulators found that dozens of these chemicals lack updated studies on developmental and reproductive toxicity.

In addition, immunotoxicity testing – critical for understanding impacts on the immune system – is not consistently required in pesticide approval processes. This has raised concerns among scientists about the adequacy of existing safety evaluations.

Another complicating factor is the presence of PFAS as so-called “inactive” ingredients in pesticide formulations. These substances can enhance performance but are not always disclosed individually, limiting visibility into total exposure risks.

Human exposure pathways

PFAS contamination in agriculture presents multiple exposure routes. Residues in food represent one pathway, while environmental runoff can contaminate groundwater, affecting drinking water supplies.

Biomonitoring data from US health agencies indicate that PFAS compounds are detectable in the blood of the vast majority of Americans, including infants. Even at low concentrations, some PFAS have been associated with immune suppression, developmental effects and increased cancer risk.

Regulatory divergence and global context

California’s regulatory framework allows the state to independently assess and approve pesticide use, separate from federal determinations. This autonomy has enabled stricter standards in some areas, though PFAS pesticides have remained widely permitted.

Other governments have moved more aggressively. Several US states have enacted or proposed bans on PFAS in various applications, including agriculture.

Internationally, the European Union has already prohibited a number of PFAS pesticide ingredients still in use in California, while Denmark has introduced targeted restrictions.

Implications for agriculture and public health

If enacted, AB 1603 would mark a significant shift in California’s approach to pesticide regulation, particularly given the state’s role as a major agricultural producer.

The proposed timeline allows for a gradual transition, but the legislation raises broader questions about the balance between agricultural productivity, chemical risk management and public health protection.

As scientific understanding of PFAS continues to evolve, policymakers face increasing pressure to address both legacy contamination and ongoing sources of exposure – especially those linked directly to the food supply.