Development of certified reference materials for the specific migration testing of plastics for food packaging

To assure consumer protection, the transfer of constituents from plastic food contact materials to the food is limited by the Plastic Directive 2002/72/EC. To show the conformity of materials with this directive, the overall and specific migration of certain monomers and additives has to be tested. The performance of laboratories during migration testing can be the source of large errors and can only be checked by the the use of reference materials with known migration values. The availability of Certified Reference Materials (CRMs) for specific migration testing would help ensuring consistent, uniform and reliable measurements. Also, they would have an important value for the validation of alternative, cost saving and rapid migration methods, both by experimentation and by predictive mathematical modelling. The main objective of EU project G6RD-CT-2000-00411 'Specific Migration' was to develop the know-how and the ability to produce CRMs for specific migration testing. A broad range of molecular sizes from the rather volatile styrene (104 Daltons) and the small caprolactam (113 daltons) to the large Irgafos 168 (647 Daltons) and different polarities from the very polar caprolactam to the non-polar additives are represented. Several contact times and temperatures have been evaluated: 20 to 100°C. 2 hours to 10 days The 6 candidate CRMs contain three polyolefins and three non-polyolefins Of the 7 migrants present in the 6 materials, 4 have specific migration limits Of the remaining three migrants Irgafos 168 is a frequently used processing stabiliser, DPBD is the test substance for the fatty contact test EN 14481, styrene is a monomer always present in polystyrenes and is discussed as a substance to be regulated by an SML in future (Synoptic Document, May 2003). Our feasibility study gives the basis for future production of very useful CRMs for specific migration testing as well as determination of additive content in the material. The data and materials produced during the project have already shown their benefits for migration research with the aim to simplify compliance testing and increase consumer safety.