Fate, Bioaccumulation, and Toxic Responses of PFOA, PFOS, and GenX in the Paddy Soil–Rice System Across the Full Growth Cycle

Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants with exceptional stability and significant ecological risk. However, their distribution and accumulation in soil–crop systems, especially for the replacement compound GenX, remain poorly characterized. Here, rice ( Oryza sativa , Nipponbare) was cultivated for five months in paddy soils amended with PFOA, PFOS, and GenX to map fate, bioaccumulation, and toxic responses across the soil–crop system and to derive soil safety thresholds protective of human health. PFAS exposure (10–100   μg/g) altered plant morphology and development and induced dose-linear oxidative stress (SOD, POD, CAT, MDA, H 2 O 2 , protein). Compound-specific translocation emerged: short-chain GenX showed greater upward transport and endosperm accumulation, whereas long-chain PFOA/PFOS were more root-retained (endosperm accumulation in total plant: PFOA 8.973–10.440%, PFOS 9.951–12.800%, GenX 10.286–20.773%). Overall toxic potency ranked PFOA ≥ PFOS > GenX. Based on measured plant uptake, we propose provisional exposure safety thresholds for rice cultivation of 3.157   ng/g (PFOA), 2.327   ng/g (PFOS), and 21.220   ng/g (GenX). This growth-cycle assessment provides an integrated evidence base for PFAS ecological risk evaluation and delivers actionable guidance to safeguard food security.