Investigation of Biological Safety and Chemical Leaching Properties in the Recycling of PP/EVOH Multilayer Plastic Food Containers

This study investigates the increase in chemical leachates and the biological toxicity associated with repeated recycling of multilayer plastic food packaging composed of polypropylene (PP) and ethylene vinyl alcohol (EVOH). Based on the ISO 10993-5 cytotoxicity assay, a slight level of cytotoxicity was detected in the recycled samples, indicating a potential biological risk associated with the use of recycled materials. Chemical analyses using ICP, pH meter, balance, UV, UV/VIS spectrophotometer confirmed a cumulative increase in the total amount of leachates. Notably, the accumulation of heavy metals was identified in the recycled plastics, which was attributed to metal components originating from the shredding and reprocessing equipment used during recycling. SEM-EDX analysis further confirmed that the accumulated metals matched the elemental composition of the recycling equipment. These findings highlight the potential accumulation of heavy metals derived from processing machinery during the recycling of multilayer packaging and underscore the need for establishing safer and more controlled recycling systems.