According to the trade association PlasticEurope, global plastics production increased to 390.7 million tons in 2021. Unfortunately, the majority of produced plastics eventually end up as waste in the ocean or on land. Since synthetic plastics are not fully biodegradable, they tend to persist in natural environments and transform into micro- and nanoplastic particles due to fragmentation. The presence of nanoplastics in air, water, and food causes ecotoxicological issues and leads to human exposure. One of the main concerns is their genotoxic potential. Therefore, this study aimed to evaluate the internalization rates, cytotoxicity, and genotoxicity of polystyrene nanoparticles (PS-NPs) in human peripheral blood mononuclear cells (PBMCs) in vitro. The uptake of PS-NPs was confirmed with flow cytometry light scattering analysis. None of the tested nanoparticle concentrations had a cytotoxic effect on human PBMCs, as evaluated by a dual ethidium bromide/acridine orange staining technique. However, an alkaline comet assay results revealed a significant increase in the levels of primary DNA damage after 24 h of exposure to PS-NPs in a dose-dependent manner. Moreover, all tested PS-NPs concentrations induced a significant amount of micronucleated cells, as well. The results of this study revealed the genotoxic potential of commercially manufactured polystyrene nanoparticles and highlighted the need for more studies with naturally occurring plastic NPs.
Keywords: comet assay; micronucleus assay; nanoplastic; peripheral blood lymphocytes; polystyrene nanoparticles.