MICROPLASTICS AS A SOURCE OF ENDOCRINE DISRUPTING CHEMICALS: EVALUATION OF THE POSSIBLE EFFECTS ON IN VITRO AND IN VIVO MODELS

Environmental pollution caused by plastic wastes is a wellknown global issue. Although environmental damages are clearly visible, the impact of macro- and microplastic particles (MPs) on living organisms is not yet well understood. For a long time, MPs have been considered non-toxic inert particles, however it has been recently found that they can distribute systemically within an organism and induce various damages in tissues, including cytotoxicity, oxidative stress, and chronic inflammation. At present, there is no evidence of a direct action of MPs as Endocrine Disrupting Chemicals (EDCs) on organisms, there is instead growing evidence on the potential of MPs to be vehicles of a wide range of compounds such as hydrophobic organic contaminants (HOCs) including EDCs, and Persistent organic Pollutants (POPs). Some indirect effects of MPs may therefore be linked to these chemicals leached or adsorbed on these particles. In order to demonstrate this hypothesis, environmental MPs were collected in the Adriatic Sea in the harbor of San Benedetto del Tronto (AP) and at different distances from the coastline. Organic extracts were obtained and analyzed, showing that MPs can be vehicles of environmental contaminants like various polycyclic aromatic hydrocarbons (PAHs), organophosphorus (OPs), organochlorine pesticides (OCs), and polychlorinated biphenyls (PCBs) congeners. Interestingly, we observed that MP extracts act in vitro as EDCs, in particular as metabolic disruptors, inducing both adipogenesis and lipid uptake/storage in 3T3-L1 preadipocyte cells. To better define the contribution of each compound to the overall pro-obesogenic effect of MP-associated endocrine disruptors, we began to test single substances alone or associated with virgin microplastics. Our preliminary results obtained in 3T3-L1 preadipocytes show that the well-known metabolic disruptors Pyraclostrobin, Tributyltin chloride and Bisphenol A (BPA) induce relevant pro-obesogenic effects. Interestingly, pro-obesogenic effects of BPA were partially reverted by simultaneous exposure of 3T3-L1 cells to (E)-β-caryophyllene (BCP), suggesting beneficial properties of nutraceuticals on reducing metabolic disruption driven by EDCs. In order to better understand the impact of MPs and associated contaminants on living organisms, in vivo studies were conducted using the zebrafish model. Danio rerio embryos were exposed to fluorescence-tagged polyethylene and polystyrene MPs and the rate of MP internalization in different organs and cell types was determined. Preliminary results show an effect of both MPs alone and combined with BPA on embryo survival, hatching rate and morphological abnormalities outcomes. Also, by means of qRT-PCR, the expression of marker genes of development was found modified in treated versus control zebrafish embryos. Our results prompt to deepen investigations on how microplastics and environmental pollutants may globally affect the health of human and wildlife organisms.