Critical review of the migration potential of nanoparticles in food contact plastics
Background The development of applications using nanomaterials is accompanied by safety concerns due to gaps in understanding the toxicology. In case of incorporation in food contact polymers, the first step to consumer exposure is the transfer of nanomaterials from the polymer to the food. Thus, in order to evaluate the risk the key questions are whether nanoparticles can be released from food contact polymers and under which conditions. Scope and Approach This article critically reviews the published nanomaterial migration studies which are partly contradictory. The influence of analytical techniques and the experimental design on the results are discussed. Theoretical approaches by mathematical modelling are addressed. Furthermore, a short overview on nanomaterial applications for food contact materials and on the regulatory situation in Europe and USA is given. Key findings and conclusions Distinguishing between particle release and migration of dissolved ions is crucial for proper interpretation of migration results. Nanosilver which is the mostly investigated species, and other metals are easily oxidized to ions but can re-form nanoparticles at slightly reductive conditions, e.g. at sample preparation, pretending particle migration. At cutting edges the particles may be released due to weak binding to the surface. Nanoparticles which are completely encapsulated in the host polymer matrix do not have a potential to migrate into food. Thus, consumers will not be exposed to nanoparticles from food contact polymers when those are completely embedded in polymer and the contact surface is not altered by mechanical surface stress during application.