Agricultural Pesticides as a Diffuse PFAS Source
A recent scientific investigation published by the Environmental Working Group has exposed a significant and widely overlooked vector for per- and polyfluoroalkyl substances in the environment: the widespread application of agricultural pesticides. For environmental consultants, property developers, local councils, and legal professionals in Australia, this research challenges long-held assumptions regarding the distribution of these persistent compounds. Historically, investigations into these contaminants have targeted point sources, specifically legacy firefighting foams used at civil and military airports, heavy industrial manufacturing plants, and active training facilities. This new data shifts the focus toward diffuse, high-volume agricultural applications that have occurred over decades across vast tracts of land.
When agricultural acreage is targeted for rezoning and urban development, standard industry practice typically limits soil and groundwater screening to historical mainstays. These traditionally include organochlorine pesticides, organophosphate pesticides, synthetic pyrethroids, heavy metals, and total recoverable hydrocarbons. However, the systemic inclusion of fluorinated active ingredients and fluorinated surfactants in registered agricultural chemical formulations means that large-scale agricultural operations represent a highly distributed, non-point source of environmental contamination. Failing to account for this historical input during initial site investigations can leave developers and consultants exposed to undetected, widespread contamination profiles.
The financial, legal, and operational risks associated with discovering diffuse contamination late in the planning or construction phase are severe. Property transactions executed without adequate due diligence may inherit substantial environmental liabilities, while local governments risk approving sensitive land-use rezonings on land that fails to meet modern health criteria. Incorporating these findings into local risk assessment frameworks is a necessary step to ensure that conceptual site models remain sound and legally defensible in an increasingly stringent regulatory climate.
EWG Study Findings on Fluorinated Pesticide Residues
The technical investigation conducted by the Environmental Working Group focused on historical data compiled by federal monitoring programmes in the United States, specifically examining conventionally grown produce in California. The analysis determined that 37 per cent of all conventionally grown, non-organic produce samples contained detectable residues of per- and polyfluoroalkyl substances. The laboratory testing, which evaluated a total of 930 individual produce samples, successfully identified 17 distinct compounds of these persistent chemicals. In several high-exposure categories, particularly certain fruits, the detection rate exceeded 90 per cent of the samples tested, indicating a highly pervasive distribution pattern across the agricultural sector.
The scale of this chemical application is extensive, with agricultural data revealing that an average of 1,133,981 kilograms (2.5 million pounds) of these fluorinated pesticides are applied to Californian agricultural land each year. This volume represents a significant, highly distributed environmental mass load. The active constituents responsible for this profile include widely utilised fluorinated synthetic organic compounds, such as trifluralin, fipronil, and fluometuron. These compounds are intentionally molecularly structured with fluorine atoms to increase their chemical stability, systemic uptake, and persistence against environmental degradation, which inadvertently mirrors the exact properties that make them environmental hazards.
Beyond the intentional active ingredients, the investigation highlighted a secondary, significant vector of contamination: the leaching of these substances from high-density polyethylene storage containers. Many liquid pesticide formulations are stored in fluorinated plastic containers, where the fluorination process used to improve plastic barrier properties produces various perfluorinated carboxylates as byproducts. These compounds, including perfluorooctanoic acid, leach directly into the pesticide formulations over time, meaning that even pesticides without fluorinated active ingredients can introduce these compounds into the soil and shallow groundwater tables during field application.
The physical and chemical behaviour of these compounds in the subsurface differs substantially from traditional agricultural contaminants like DDT or dieldrin. Traditional organochlorine pesticides are highly hydrophobic, binding tightly to organic matter in the upper soil profile. In contrast, many of these modern fluorinated compounds and their degradation products exhibit moderate to high water solubility and low sorption coefficients. This allows them to migrate rapidly through the vadose zone into shallow aquifers or run off into surface water catchments and irrigation drainage networks, converting localised agricultural applications into regional groundwater management challenges.
Australian context
In Australia, the identification and management of contaminated sites are governed by a robust national framework, primarily led by the National Environment Protection (Assessment of Site Contamination) Measure 1999, which was significantly revised in 2013. Schedule B2 of this measure mandates the development of a comprehensive Conceptual Site Model for every investigated property. A Conceptual Site Model must identify all potential historical sources of contamination based on site history. Given the evidence of widespread agricultural use of fluorinated compounds, excluding these persistent chemicals from the initial Contaminants of Potential Concern list on historical agricultural sites is becoming increasingly difficult to defend during initial site history assessments and statutory audit reviews.
References and related sources
- Primary source: www.ewg.org
- PFAS National Environmental Management Plan (NEMP)
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This is an iEnvi Machete news summary. Prepared by iEnvi to summarise the source article for contaminated land, groundwater, remediation, approvals and site risk professionals.
Published: 17 Jun 2026
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