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Modeling and characterization of per- and polyfluoroalkyl substances (PFASs) uptake into food crops and human health risk assessment from dietary exposure
Bowman, Juliane
Bowman, Juliane
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2024
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2026-04-09
Abstract
Per- and polyfluoroalkyl substances (PFASs) are a broad class of fluorinated chemicals found in consumer products and industrial processes and present throughout the environment. Aqueous film forming foams (AFFF), used in firefighting, contribute complex PFAS mixtures to the environment. Health risks from consuming PFAS-contaminated food crops are poorly understood. Uncertainties remain about how PFAS mixtures, like those in AFFF, are absorbed by plants and how uptake translates into dietary risk. This research addresses knowledge gaps about PFAS uptake into plants and risk assessment of consuming PFAS-impacted crops.
The first objective used a Monte Carlo simulation to estimate dietary PFAS intake from vegetables for different age groups, estimated risk-based thresholds in irrigation water and produce, and compared hazard analyses using real-world PFAS data for a hypothetical farm. Modeling results showed that young children face the highest dietary exposures to PFASs, and elevated irrigation water concentrations might not be protective against vegetable contamination, while hazard analyses of PFAS mixtures exceeded toxicity reference values.
The second objective evaluated techniques to characterize PFAS uptake in tomato plants. Transpiration stream concentration factors (TSCFs) from pressure chamber experiments determined from root solution and xylem sap were compared to uptake data from hydroponics studies. Pressure chamber experiments yielded variable TSCFs, with some PFASs not reaching steady state, indicating this method may not accurately reflect PFAS uptake in hydroponics systems. The hydroponics experiment showed different TSCF and uptake patterns not representative of soil-water-plant systems.
The final objective determined bioaccumulation and translocation factors in radish, lettuce, and tomato plants grown with AFFF-spiked water or spiked soil. This work found that although many AFFF-derived PFASs in the irrigation water were either not absorbed by plants or were transformed into terminal PFASs, some non-terminal PFASs were identified in the plant tissues, indicating possible dietary exposure to these additional PFASs. Bioaccumulation results indicate that consumption uptake models distinguishing between root crops (such as radish), leaf crops (such as lettuce), and fruit crops (such as tomato) might be the most suitable method for assessing exposure from crops cultivated in PFAS-contaminated soil or water. The AFFF uptake study reveals that PFASs and their precursors from AFFF can translocate and accumulate in some plant parts suggesting that dietary guidelines focusing only on a few terminal PFASs may not capture exposure risk from additional PFASs in contaminated food.
These findings are useful for risk assessors and regulatory authorities responsible for safeguarding human health, offer practical guidance for evaluating risks from consuming PFAS-impacted crops, and provide insights into plant uptake methods and processes.
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