Assessment of the cytotoxicity micro- and nano-plastic on human intestinal Caco-2 cells and the protective effects of catechin†

Micro- and nano-plastics (M/NPs) potentially leach from plastic wrapping into food and beverages. However, the risks of ingested M/NPs to human intestinal health remain unclear. This study aimed to determine the potential risks and mechanisms of PS-M/NPs using a human intestinal epithelial in vitro model and to explore protective measures to reduce these risks. The results showed that polystyrene (PS) M/NPs exhibited size-dependent cytotoxicity (3 μm < 0.3 μm < 80 nm < 20 nm). Additionally, by measuring intracellular reactive oxygen species (ROS) production after exposure to PS-M/NPs and the elimination of ROS by N-acetyl-L-cysteine, we identified oxidative stress as a mechanism of PS-M/NP-induced cytotoxicity. Hazard quotients calculated from the study indicated that the risks of M/NPs derived from plastic teabags exceeded the margin of safety, suggesting that ingested M/NPs potentially pose a risk to human intestinal health. Furthermore, this study found that catechins can reduce the adverse effects of M/NPs, so we propose that drinking tea may offer a protective effect against the harm of M/NPs on the intestinal system.