Food contact materials (FCMs) contain large numbers of chemicals, which can potentially migrate into food. They include known substances with defined technological functions, but also the so-called NIAS (Non Intentionally-Added-Substances) originating for examples from impurities in starting materials and from chemical reactions during FCM manufacturing. Many NIASs are not chemically and toxicologically characterized. While there is currently no consensus on how to identify the NIAS of concern, it has increasingly been acknowledged that an approach based on identification/quantification of all substances in FCM migrates/extracts, together with their full toxicological characterisation, is neither practical nor desirable. A recent ILSI-Europe initiative recognized the Cramer class III Threshold of Toxicological Concern (Cramer class III-TTC) as a promising tool to determine the NIAS on which additional identification effort should focused. To apply the Cramer class III-TTC to unknown chemicals in a NIAS mixture requires excluding the presence of direct DNA-reactive mutagens. The ILSI-Europe Packaging TF convened an expert group (EG) to address the potentials of in vitro genotoxicity testing of FCM migrates/extracts to support the use of the Cramer class III-TTC for prioritization of unidentified NIASs.

Objectives
Bring together key stakeholders to critically review the work of the EG. The draft manuscript shared in advance of the workshop will constitute the basis for discussion. The following topics will be addressed through three breakout working groups:

• Sample preparation: FCM extraction versus migration studies, compatibility with bioassays
• Bioassays for genotoxicity testing: which tests?; limit of detection for genotoxins
• Data interpretation and use: integration of bioassay data with chemical information to decide on the applicability of the Cramer class III-TTC to prioritize NIASs

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