Persistent organic pollutants, represented by perfluorooctanoic acid (PFOA), have traditionally been evaluated for aquatic toxicity through static end point analyses, particularly lacking time-series analyses of dynamic metabolic pathways. This study integrated noninvasive skin mucus sampling with extractive electrospray ionization mass spectrometry (EESI-MS) to, for the first time, longitudinally and continuously track metabolic trajectories in individual Nile tilapia exposed to PFOA (0.2-20 μg/L) over 21 days. Dynamic responses of oxidative stress biomarkers and metabolomic profiles were systematically characterized through integrated analyses. Utilizing the three-dimensional extraction-ionization capability of EESI-MS, the temporal dynamics of 249 differential metabolites were captured, revealing a three-stage progression of toxicity: in the early exposure stage (days 1-3), histidine metabolism was activated to alleviate oxidative stress; in the midstage (days 7-14), glutathione and arachidonic acid metabolism were enhanced, signaling the initiation of antioxidant defense and inflammatory cascades; in the late stage (day 21), tryptophan metabolic disturbances may have triggered neurological dysfunction. The study unveils the progressive toxicity mechanism of PFOA from oxidative damage to neurotoxicity, providing a transformative monitoring paradigm for real-time risk assessment and ecological toxicity classification of per- and polyfluoroalkyl substances (PFASs) in aquatic environments.
Wang et al. (Sun,) studied this question.