From Field to Fork: PFAS Uptake in Irrigated Agriculture
The use of PFAS-contaminated water for agricultural irrigation represents a potentially underestimated pathway for human PFAS exposure through food. As water utilities test for PFAS and contamination is increasingly detected in surface water and groundwater sources used for farm irrigation, agricultural regulators and food safety agencies face urgent questions: which crops absorb PFAS? At what soil and water PFAS concentrations does food safety become a concern? And how do farmers adapt their operations when irrigation water is found to be contaminated?
Plant Uptake Mechanisms and Influential Factors
Plants absorb PFAS from soil and irrigation water primarily through root uptake, with the extent of absorption influenced by PFAS chain length, functional group, soil organic matter content, soil pH, and plant species. Short-chain PFAS and PFAS carboxylates are generally more water-soluble and bioavailable to plants than longer-chain sulfonates. Leafy vegetables—including lettuce, spinach, kale, and herbs—show higher PFAS accumulation than fruiting vegetables like tomatoes, peppers, and cucumbers, because PFAS transported via xylem flow tends to concentrate in leaves rather than fruit.
Root vegetables occupy an intermediate position: radishes, carrots, and beets accumulate PFAS in their edible portions at rates dependent on soil PFAS concentrations, while the soil-contact surface area determines exposure. Grain crops generally show lower PFAS translocation to grain compared to vegetative plant parts, though even small fractions of total plant PFAS burden may contribute meaningfully to dietary exposure through the large quantities of grain-derived foods consumed globally.
Case Studies: Irrigation Contamination Events
Several high-profile agricultural PFAS contamination events have illustrated the food safety implications of contaminated irrigation water. In Oakdale, Pennsylvania, farms irrigating with water from a PFAS-contaminated municipal supply were found to be producing vegetables with elevated PFAS content above FDA thresholds. In Maine, widespread dairy farm contamination from PFAS-laden biosolids applied as fertilizer resulted in farm closures, well water advisories, and livestock sampling programs—revealing the interconnected nature of water, soil, crop, and animal food chain PFAS contamination pathways.
The Maine contamination events led to the state’s development of PFAS soil action levels for agricultural land—among the first such standards in the United States—and prompted other states to develop or accelerate their own agricultural PFAS frameworks. The U.S. Department of Agriculture (USDA) and FDA are jointly developing guidance on PFAS testing for farms using potentially contaminated water sources and soils receiving biosolid amendments.
Policy Responses and Farmer Support Programs
Farms discovered to have PFAS-contaminated irrigation water or soils face severe economic consequences: crop sales may be restricted, markets may reject produce, and whole-farm income can collapse overnight. Several states have developed farmer compensation programs for farms affected by PFAS from identifiable external sources (particularly biosolids from publicly owned treatment works). Maine established a groundbreaking PFAS fund providing direct payments to affected farmers. Federal legislation under consideration would extend support nationwide, recognizing that individual farmers should not bear the full economic burden of contamination from industrial sources they did not control.