Uptake Routes and Biodistribution of Polystyrene Nanoplastics on Zebrafish Larvae and Toxic Effects on Development

Polystyrene (PS) is the most widely used plastic polymer. It is mainly used to produce disposable products. Due to its resistance to degradation, PS can remain in the environment for a long time. Its mechanical, physical and biological actions determine the release of smaller fragments, which are able to penetrate organisms and accumulate in target organs. Fertilized Danio rerio eggs were exposed to concentrations of 10 and 20 mg/L of fluorescent, amino-modified polystyrene nanoplastics (nPS-NH2) with diameters of 100 and 50 nm for 96h, according to OECD guidelines (2013). Uptake, biodistribution, toxicity, oxidative stress and apoptosis were evaluated; moreover, we carried out a simulation to study the interactions between nPS-NH2 and defined regions of three receptors: STRA6, Adgrg6 and CNTN4/APLP2. We demonstrated that after being internalized, nPS-NH2 could reach the head and bioaccumulate, especially in the eyes. Moreover, they could lead to oxidative stress and apoptosis in the several regions where they bioaccumulated due to their interaction with receptors. This study confirmed the danger of nanoplastic wastes released in the environment.