Per- and polyfluoroalkyl substances in land-applied biosolids: Accumulation in soils, crop uptake, and potential...

Applying biosolids as a soil amendment for crop production is a common practice, raising concerns about the introduction of per- and polyfluoroalkyl substances (PFAS) into soils and crops at application sites. We investigated the impact of biosolids application on PFAS concentrations in agricultural soils and crops at three different farms that received biosolids from three different wastewater treatment plants in Minnesota. At each farm, three fields were identified: one with no history of biosolids application, one with past biosolids application, and one with biosolids application in the study year (2023). Biosolids; soils; and corn (Zea mays), rye (Secale cereale), and soybeans (Glycine max) were analyzed for PFAS. Biosolids-amended soils showed a greater number of PFAS, as well as higher total PFAS concentrations than fields that had never received biosolids or had not received biosolids in recent years. Several PFAS, including perfluorooctane sulfonate (PFOS), were found to accumulate in corn, especially in the stalks and leaves (stover). PFAS were also found in rye, but not in soybeans. Bioaccumulation factors for crops were calculated for perfluorobutane sulfonate (5.0-5.2, corn stover), perfluorobutanoic acid (0.57, rye, and 7.0-7.7, corn stover), perfluoropentanoic acid (0.34, corn stover), and PFOS (0.03, corn stover). Crop and soil results were used to perform a human health risk assessment using a simple exposure model to estimate PFOS concentration in beef and milk. Hazard quotients were >1 for both adults and children based on 90th percentile consumption rates, indicating a potential for human health risk in the modeled scenario.