The US Food and Drug Administration (FDA) and European Commission (EC) have carried out theoretical and experimental researches on migration of chemical substances.Migration of chemical substances from plastic packaging materials into foods contaminates foods and finally endangers people’s health

and has been widely studied and discussed.Numerical simulation of migration of chemical substances (migrants) from plastic food packaging materials into foods and the instability of migrants in foods were performed by using the finite difference method (FDM).The results showed that the diffusivity of migrants DP was key to migration dynamics.Partition coefficient KP

F represents the ratio of migrant concentration in packaging materials to that in foods at equilibrium.The concentration of migrants in foods at equilibrium increased with the increase of its initial concentration in packaging materials.For multilayer packaging

functional barrier layer was able to efficiently delay migration and assure food safety.The thickness of barrier layers influenced the barrier effect and then the ability to protect foods from contamination.The instability of migrants in foods is a problem newly found and leads to underestimation of migration.