Synergistic toxicity of PFAS and microplastic mixtures across five human cell lines

Per- and polyfluoroalkyl substances and microplastics (MPs) are ubiquitous environmental contaminants that frequently co-occur in aquatic ecosystems and human exposure pathways. While their individual toxicities have been extensively studied, the combined effects of PFAS and MP co-exposure on human health remain poorly understood. This study evaluated cytotoxic, oxidative, and genotoxic responses in five human-derived cell lines-A498 (kidney), HepG2 (liver), PC3 (prostate), A431 (skin), and A549 (lung)-following exposure to environmentally relevant concentrations of perfluorooctanoic acid (PFOA), hexafluoropropylene oxide-dimer acid (GenX), polystyrene, and low-density polyethylene, both individually and in mixtures. Our findings showed potential synergistic effects were observed primarily in kidney and liver cell lines, including increased reactive oxygen species production, elevated antioxidant gene expression, and activation of DNA repair pathways. Mixture toxicity was dependent on both dose and PFAS-to-MP ratio, with synergistic responses predominating. A498 cells consistently showed greater sensitivity than HepG2 across all toxicity endpoints, including increased ROS, antioxidant gene expression, and activation of DNA repair pathways. HepG2 cells exhibited more limited oxidative stress responses but showed significant DNA damage and H2AX upregulation in select treatments. Gene expression data suggest differential activation of redox and DNA damage response pathways between the two cell types. These findings highlight the need to incorporate mixture toxicity into risk assessments and identify oxidative stress and genotoxicity as central mechanisms of concern in PFAS and MP co-exposure.