Per- and polyfluoroalkyl substances (PFAS) have been identified as chemicals of concern in agricultural soils, biosolids-amended soil, and irrigation water due to their toxicity, persistence, bioaccumulation potential and occurrence in these media. The agricultural use of PFAS-contaminated water, municipal and industrial biosolids, and municipal compost can all contribute to the exposure of food crops to PFAS.
Irrigation water containing variable levels of PFASs may contaminate soil over time resulting in additional exposure pathways to food crops. The uptake and accumulation of PFAS in food crops is an important and continuing concern for protecting human health. There is an urgent need for regulatory agencies to assess the accumulation of PFAS in the edible portion of food crops as consumers often eat these foods fresh or with minimal processing. Recognition of PFAS in food as a potentially important contributor to human exposure, as well as the identification of PFAS-impacted irrigation water and soils in areas with agricultural activities, has resulted in several studies on the uptake of PFAS into crops. Using available crop-specific transfer factors (TFs) from lettuce bioaccumulation studies, exposure data, and consumption rates for homegrown produce, exposure intakes are estimated for a range of concentrations for different population subgroups using Monte Carlo Simulation in a tiered stochastic modeling approach. For PFASs with oral toxicity reference doses, risk-based concentrations (RBCs) for selected PFAS in contaminated soil and irrigation water were determined for adults and children. The RBCs are compared to available health advisories or criteria and the influence of other exposure pathways is evaluated. Lastly, we explore the utility and challenges of implementing a relative potency factor approach to assess risk from a mixture of PFAS. Prediction outcomes from a hypothetical farm illustrate the model application to a real-world scenario.