Cytotoxicity and Genotoxicity of Polystyrene Microplastics with Different Size and Surface Modification in A549 Human Lung Cells

Abstract

Microplastics (MP) have become an environmental issue of global concern due to their small size, high specific surface area and strong bio-permeability. Recently, a variety of microplastics have been detected in atmospheric samples, indicating potential harm to the human respiratory system. However, few studies have assessed the effect of polystyrene nanoplastics (PS-NPs) on human lung cells. In this study, we evaluated the cytotoxicity and genotoxicity of PS-NPs with different sizes (2 μm and 80 nm) and surface modification (pristine polystyrene; carboxy and amino functionalized polystyrene, PS-COOH and PS-NH 2 , respectively) in A549 human alveolar epithelial cells. Our research showed that the cytotoxicity and genotoxicity of A549 cells caused by nano-level PS-NP is more serious than that of micro-level, which may be due to its smaller size and higher biological reactivity, increased intracellular accumulation, and stress-induced mitochondrial apoptosis and oxidative damage. Compared with unmodified PS, more surface-functionalized nanoplastics were found inside the cells, especially the accumulation of PS-NH 2 . Cell viability and the induction of micronuclei (MN) are significantly affected in a dose-dependent manner. Functionalized PS-NPs showed greater cell viability inhibitory ability than PS, and induced more MN scores, which may be due to the accumulation of intracellular PS-NPs and the increase of oxidative stress caused by lysosomal leakage and mitochondrial damage-mediated apoptosis. This study shows that the intrinsic size properties and surface modification of PS-NP, the interaction between PS-NP and the receiving medium, endocytic pathways, and intracellular accumulation are key factors for evaluating the toxicological and genotoxic effects of microplastics on humans. More attention must be focused on the risk of nanoplastic-related air pollution and the environmental cytotoxic outcomes of nanoplastics in humans and other terrestrial mammals.

Keywords: Microplastics, Surface functionalization, Cytotoxicity, genotoxicity, Oxidative damage