EVALUATION OF THE EXPOSURE TO MICROPLASTICS AND ASSOCIATED CONTAMINANTS IN IN VITRO AND IN VIVO MODELS

Plastic pollution is an emerging global concern. In addition to damages caused by large plastic wastes, there is increasing attention on Microplastics (MPs), ubiquitous environmental pollutants potentially dangerous for human and wildlife health. Moreover, there is growing evidence of the potential of MPs to become vectors of a wide range of contaminants, such as Endocrine Disrupting Chemicals (EDCs), possibly responsible for some indirect effects. In our study, we focused on 5 μm and 0.5 μm polystyrene microplastics (PS-MPs), both pristine and functionalized (-COOH), as carboxylated MPs may mimic environmentally aged MPs. We assessed the impact of MPs exposure both in vitro, using human liver cancer, murine pre-adipocyte, and bovine aortic endothelium cell lines, and in vivo, in zebrafish (zf) larvae. MPs were internalized by cultured cells and ingested by zf larvae, accumulating in the intestine. In vitro cytotoxic effects were observed only in cells exposed to very high concentrations of functionalized MPs. In zf larvae survival, hatching, and heartbeat were monitored until 6 dpf; virgin-MPs exposure did not lead to macroscopic deleterious effects on developing organisms. To investigate the potential role of MPs as vectors of contaminant chemicals, the adsorption of Bisphenol A (BPA), a well-known EDC, on PS-MPs was tested using a UHPLC-tandem MS method. Following a 24 h incubation, the adsorption yield of BPA (25 μM) on PS-MPs was about 50%. In our experimental models, the exposure to MPs preadsorbed with non-toxic concentrations of BPA had no toxic effects. We are currently testing other biological effects, including the induction of oxidative stress, changes in triglyceride accumulation, and alterations in gene expression. Our results suggest that PS-MPs are ingested by zf larvae and internalized in cultured cells, leading to toxic effects only at high concentrations. More in-depth investigations are needed to evaluate subtle metabolic and developmental effects of contaminant-associated MPs.