Abstract
This study, one of the few conducted to date on working farms in the US, examined per- and polyfluoroalkyl substances (PFAS) contamination in 10 farms treated with biosolids using a paired control-treatment approach. Biosolids are nutrient-rich and inexpensive soil amendments, however, if the biosolids contain PFAS which are known to be toxic, mobile and to bioaccumulate, they can leave lasting negative impacts on farming soil and water. Our study showed significantly higher concentrations of PFAS in biosolids-treated (treatment) soils compared to (untreated) controls. Soil depth, soil physicochemical properties (e.g., organic matter and pH), and biosolids sources affected concentrations and types of PFAS in treated soils. While PFAS precursors were present in biosolids, they were absent in treated soils, likely due to biotransformation to terminal perfluoroalkyl products. The detection of shorter-chain PFAS in surface water highlights their greater mobility, raising concerns beyond the boundaries of the biosolids-treated farms.