Subcellular toxicity assessments of microplastics released from food containers.

Plastic food containers are widely used for food packaging and storage; however, concerns have arisen regarding the potential releases of microplastics (MPs) from these containers under varying temperature conditions. This study investigated the release and potential cytotoxicity of MPs from food containers subjected to cooling and heating. Caco-2 cells were selected for in vitro studies to assess the toxicity of MPs from food containers. Each food container released approximately 100,000 to 260,000 plastic particles. The total weight of these plastics was between 0.1 and 0.3 mg of each container after extraction. The results revealed the presence of MPs in both polypropylene (PP) and polystyrene (PS) containers, with frozen food containers releasing a greater quantity of smaller plastic particles. The cytotoxicity of the MPs showed a dose-dependent decrease in cell viability, particularly with MPs from frozen food containers. To further investigate the cellular responses to MPs released from food containers, cellular uptake was visualized using Nile Red staining and confocal microscopy. Changes in cellular organelles and enzyme activities were also observed to reveal the potential effects of MPs. Among all treatments, PS food containers stored in frozen conditions exhibited the most significant cellular responses, including alterations in lysosomal number, size, and reactive oxygen species formation. Compared to cell viability, subcellular responses were found to be more sensitive to MPs. Overall, this study provides valuable insights into the presence, properties, and potential health impacts of MPs released from food containers under microwave heating. The findings underscore the need for further research and regulatory measures to mitigate the risks associated with MPs and promote the development of sustainable alternatives in food packaging.