Biological Fate of Food-Pakaging Microplastics: Generation Processes and In Vivo Toxicity

Microplastics (MP) are widely distributed in the natural environment as emerging pollutants, primarily entering and accumulating in living organisms through oral ingestion. The release of microplastics from food packaging into the atmosphere and their health risks to the gut and liver remain largely unknown. This study demonstrated that disposable plastic cups released PET microplastics (PET-MPs) into the environment during takeout delivery. Following 20 weeks of exposure to low-dose (14 mg/kg/day) and high-dose (70 mg/kg/day) PET-MPs, SD rats exhibited significantly worsened liver damage and oxidative stress. PET-MPs induced ferroptosis by inhibiting the Keap1-Nrf2 pathway and its downstream target proteins. Concurrently, PET-MPs were confirmed to damage colonic tissue, disrupt intestinal barrier integrity, thereby upsetting gut microbiota balance and reducing short-chain fatty acid (SCFAs) production. Correlation analysis between liver injury and gut microbiota highlighted the crucial role of the gut-liver axis in PET-MPs-induced liver damage. Results indicated that PET-MPs exacerbate liver injury by stimulating liver inflammatory cascades through the inhibition of the Keap1-Nrf2 pathway, with gut barrier dysfunction and microbiota modulation contributing to this process. In conclusion, characterizing microplastics released from food packaging and investigating their intestinal and liver toxicity upon dietary ingestion provides a theoretical foundation for understanding microplastic health hazards.