Uptake, accumulation, and toxicity of per- and polyfluoroalkyl substances in Allium cepa grown in soils amended with biosolids

Uptake and accumulation of per- and polyfluoroalkyl substances (PFAS) in Allium cepa from soils amended with biosolids were investigated. The Ʃ38 PFAS concentrations in soils amended with biosolids ranged from 10.4 to 104 ng g−1 (dry-weight). Among PFAS, perfluorooctanesulfonate (PFOS) concentration was the highest in soils, with a maximum of 48.1 ng g−1, followed by N-ethylperfluoro-1-octanesulfonamidoacetic acid (N-Et-FOSAA) with the maximum of 10.9 ng g−1. The concentration of perfluorooctanoate (PFOA) was higher (0.55–1.82 ng g−1) in roots of A. cepa than that of PFOS (0.03–0.13 ng g−1). The accumulation of PFAS in A. cepa shoots depended on the carbon chain length, with a more significant accumulation of shorter C-chain PFAS than the longer C-chain derivatives. The concentration of PFAS in shoots correlated positively with corresponding root concentration, suggesting a significant translocation of PFAS from root to shoots. A. cepa showed no considerable cyto-genotoxicity in the meristem root tip cells exposed to soils amended with biosolids. The oxidative stress parameters such as reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and lipid peroxidation (LP) showed no significant change over control in A. cepa root cells exposed to soils amended with biosolids. The estimated dietary intake for PFOA and PFOS did not exceed the recommended tolerable daily intake (TDI) even after assuming that onion accounted for 100% of vegetable consumption. This study provides evidence of accumulation and translocation of PFAS from soil to roots and shoots of A. cepa. Also, we assessed the potential risk of PFAS accumulated in A. cepa to humans via the food chain to be insignificant