Contrasting Uptake Patterns: DGT Reliably Predicts Zebrafish Bioaccumulation of Long-Chain but Not Short-Chain PFAS

The environmental behavior of per- and polyfluoroalkyl substances (PFAS) is influenced by their physicochemical properties, including chain length. In situ passive sampling techniques such as diffusive gradients in thin films (DGT) can help elucidate these processes. Here, we report for the first time a systematic comparison between DGT and zebrafish bioaccumulation for eight sulfonated PFAS. The results showed distinct bioaccumulation patterns depending on chain length. Long-chain PFAS exhibited significantly greater accumulation in zebrafish due to their stronger hydrophobicity and binding affinity for proteins and phospholipids, whereas short-chain PFAS showed limited accumulation and rapid saturation. We found that DGT accurately reflected zebrafish uptake of long-chain PFAS (PFHxS, PFOS, OBS; R 2 > 0.95) and moderately for 6:2FTS ( R 2 = 0.66), but not for short-chain analogues (C ≤ 4), likely attributable to their low accumulation and rapid elimination in fish. Given the relatively high bioaccumulation potential and toxicity of long-chain PFAS, assessing their environmental bioavailability is critical. Our findings highlight DGT as a promising noninvasive tool for assessing the bioavailability of concerning long-chain PFAS, while cautioning its limitations for short-chain compounds.