Microwave Heating and Freeze-Thaw Cycles Exacerbate Microplastics and Nanoparticles Release from Plastic Takeout Food Containers: Characterization and Health Risk Assessment

With the rapid development of the food delivery industry, plastic takeout food containers have become essential in daily life. However, these containers may release microplastics and nanoparticles during use, posing potential health risks. This study simulated five usage scenarios during the consumption of takeout food, characterized microplastics(MPs) and nanoparticles release from five types of plastic takeout food containers, and assessed associated health risks. Under the same conditions, the materials ranked in terms of microplastics release as follows: polypropylene (PP) < polyethylene terephthalate (PET) < polystyrene (PS) < polyethylene (PE) < polylactic acid (PLA). MPs abundance ranged from 0.72 × 10 4 - 5.83 × 10 4 n/L. PLA plastic food containers exhibited the highest MPs release, likely attributable to their internal structural instability. The particle size distribution of MPs ranged from 1-16 μm. In terms of morphology, fragment were the predominant shape, accounting for 82.60% of the total. Notably, nanoparticles were present in quantities 4-5 times greater than the release MPs, posing a heightened risk of translocation across biological barriers. Health risk assessments revealed that the annual intake from PP takeout food containers was below the safety threshold set by the European Union, while the intake from PLA takeout food containers was close to the thresholds. Under microwave conditions, the Target Hazard Quotient for every material attained its maximum point. Consumers are advised to prioritize the use of PP takeout food containers as a food container material while avoiding its reuse and microwave heating.