Enhanced hepatic cytotoxicity of chemically transformed polystyrene microplastics by simulated gastric fluid*

Microplastics pollution has emerged as one of the top-ranked global environmental issues, receiving worldwide attention in recent years. However, knowledge about the detrimental effects of microplastics on human health is still limited. In real-world settings, the physicochemical characteristics of microplastics were modified by environmental and biological transformation, largely changing their ultimate toxicity. Nonetheless, the toxicity change related to transformation of microplastics has not been considered in most published studies thus far. In the current study, we investigated the cytotoxicity of transformed polystyrene microplastics in hepatocytes. Our results revealed that 500 nm polystyrene microplastics, which were chemically transformed by simulated gastric fluid, exacerbated their adverse effects on SMMC-7721 cells at 20 ?g/mL for 24 h treatment, including morphological alteration, membrane damage and increased cell apoptosis via oxidative stress. This exacerbated cytotoxicity could be at least partially explained by the degradation, changed surface charge and altered surface chemistry of these polystyrene microplastics after transformation. In conclusion, our study demonstrates that the hepatic cytotoxicity of polystyrene microplastics is enhanced after transformation.

Automated summary

Microplastics pollution is a global environmental issue that has received widespread attention, but limited knowledge exists on the detrimental effects of microplastics on human health. This study found that transformed polystyrene microplastics exhibited enhanced cytotoxicity in hepatocytes, with effects including morphological alteration, membrane damage, and increased cell apoptosis through oxidative stress. The exacerbated cytotoxicity was attributed to changes in degradation, surface charge, and surface chemistry of the microplastics after transformation.