Development of a Long-term Migration Test Method for Plastic Food Utensils, Containers, and Packaging

To ensure the safety of plastic food utensils, containers, and packaging, migration testing is essential for the qualitative and quantitative analysis of chemical substances that migrate from these materials into foods. In the context of foods with shelf lives ranging from several months to several years, conducting actual long-term migration tests is particularly challenging. It is therefore necessary to establish accelerated test conditions that yield equivalent migration levels. In order to establish such accelerated test conditions, results obtained from long-term migration tests using food-simulating solvents are required. However, when conducting long-term migration tests, concerns arise regarding the spoilage of food-simulating solvents and the adsorption of migrated substances onto the test container. To address these problems, model samples were prepared by incorporating ten substances with a wide range of Log Pow values into eight types of general-purpose synthetic resins. Using four types of food-simulating solvents (water, 4% acetic acid, 20% ethanol, and olive oil), potential methods for long-term migration testing were examined. An analytical approach based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) was evaluated and confirmed to be applicable for use with the various food-simulating solvents. More specifically, in the long-term migration test using water, a decrease in the migration amount of dimethyl isophthalate was observed in high-impact polystyrene and polyamide due to the influence of microorganisms proliferating within the migration solution. It was also demonstrated that the addition of sodium azide is effective in preventing spoilage. Furthermore, it was confirmed that the adsorption of substances with Log Pow values of <6 onto glass containers could be considered negligible. Using the LC-MS/MS-based long-term migration test protocol established in this study, it becomes possible to examine conditions for setting accelerated test parameters.