A long-term cell culture model combining targeted mass spectrometry and transcriptomics suggests that low-dose exposure to per- and polyfluoroalkyl substances (PFAS) can alter cellular metabolism – even when intracellular accumulation remains minimal.
In the study, researchers exposed hTERT RPE-1 human epithelial cells to environmentally relevant concentrations of two widely studied PFAS compounds – perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) – over a 24-week period. Intracellular PFAS levels were quantified at multiple time points using a matrix-matched liquid chromatography–tandem mass spectrometry (LC–MS/MS) method with isotopically labeled internal standards. RNA sequencing and lipidomics were then used to examine downstream molecular responses.
To examine how PFAS levels changed over time, the researchers quantified intracellular concentrations at four points across the exposure period – 24 hours, 7 weeks, 17 weeks, and 24 weeks. Results from this time-course analysis revealed limited intracellular accumulation: PFOS concentrations increased rapidly within the first 24 hours but stabilized thereafter, reaching mean levels of around 0.40 ng per mg of cellular protein. PFOA, by contrast, remained below the method’s limit of detection throughout the study.
Despite the lack of substantial accumulation, multi-omic analyses revealed clear molecular responses to prolonged exposure. Transcriptomic profiling identified changes associated with oxidative stress pathways and lipid metabolism, while lipidomic measurements indicated shifts consistent with membrane remodeling and altered lipid composition.
Together, these results suggest that chronic PFAS exposure can trigger adaptive cellular responses even when intracellular concentrations remain low. The authors note that the molecular signatures observed in the study point to coordinated regulation of oxidative stress pathways, lipid metabolism, and membrane dynamics following prolonged exposure.
They further suggest that PFAS toxicity may not depend on sustained intracellular accumulation, but could instead arise from persistent interactions with cellular membranes and associated stress responses. However, they caution that the simplified in vitro system cannot fully capture the complex toxicokinetics and tissue-specific responses observed in vivo.
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