Food contact materials (FCMs) can transfer chemicals arising from their manufacture to food before consumption. Regulatory frameworks ensure consumer safety by prescribing methods for the assessment of FCMs that rely on migration testing either into real-life foods or food simulants. Standard migration testing conditions for single-use FCMs are justifiably conservative, employing recognized worst-case contact times and temperatures. For repeated-use FCMs, the third of three consecutive tests using worst-case conditions is taken as a surrogate of the much shorter contact period that often occurs over the service life of these items. Food contact regulations allow for the use of migration modelling for the chemicals in the FCM and for the partitioning that occurs between the FCM and food/simulant during prolonged contact, under which steady-state conditions are favored. This study demonstrates that the steady-state is rarely reached under repeated-use conditions and that partitioning plays a minor role that results in migration essentially being diffusion controlled. Domains of use have been identified within which partitioning does not play a significant role, allowing modelling based upon diffusion parameters to be used. These findings have the potential to advance the modelling of migration from repeated-use articles for the benefit of regulatory guidance and compliance practices.

The current migration assessment requirements regarding safety of plastic food contact materials in Europe (e.g. kitchen utensils, kitchen appliances, packaging, etc.) widely rely on migration testing. According to Annexe V of Regulation (EU) No 10/2011 migration testing requirements consider the specificities of repeated use applications only to a limited extent. Repeated use food contact materials should be tested for three consecutive times at the worst-case contact time and temperature. If diffusion controlled, the migration decreases with increasing number of repeated uses. Compared to single use applications, repeated use food contact materials typically exhibit much shorter contact times, much lower ratios of surface in contact with a given amount of food, and in some cases higher temperatures. Compared to real use, in many cases highly overestimated migration testing result are observed. Overestimation by testing at the beginning of use may be coupled with underestimation at later times. National legislation of the Netherlands on food contact materials has established a classification for repeated use rubber materials based on the R-value indicating whether migration testing is required or not. The R-value considers in more detail specificities of repeated use applications. This publication investigates to which extent it is possible to apply the approach to plastics food contact materials in Europe. It is practically impossible to perform migration tests for various materials by putting them many times in contact with food over a long period of time, typically several years, at several temperatures and areas to food amount ratios migration. Modelling has therefore been used to predict migration from various food contact materials under different repeated use scenarios. Realistic diffusion properties of materials and migrant partitioning behaviour have been assumed to minimise the risk of underestimation.