On January 12, 2016 the European Food Safety Authority’s (EFSA) Panel on Food Contact Materials, Enzymes, Flavorings and Processing Aids (CEF Panel) published a scientific opinion on the safety assessment of tetraethyl orthosilicate (TEOS, CAS 78-10-4) and hexamethyldisilazane (HMDS, CAS 999-97-3) for use in food contact materials (FCMs). The two substances are used as a chain extender in recycled polyethylene terephthalate (rPET) to increase molecular weight. Articles made from the rPET are intended for contact with all types of foodstuffs, with or without prior pasteurization, for long-term storage at room temperature. Measurements of residual content in the rPET suggest that TEOS and HMDS react completely with the PET chains. Further, a migration study showed that detected migrating substances from rPET using TEOS and HMDS correspond to oligomers identical to those from the virgin PET, at an estimated detection level of 3 μg/kg. Based on toxicological data, the CEF panel concluded that there is no indication of genotoxic potential for TEOS and HMDS. Therefore, the CEF Panel considers the mixture of TEOS and HMDS in a ratio of 97:3 safe for use in the production of rPET at up to 0.12% weight by weight.

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CEF (January 12, 2016). “Scientific Opinion on the safety assessment of the substances tetraethyl orthosilicate, CAS No. 78-10-4, and hexamethyldisilazane, CAS No. 999 97 3, for use in food contact materials.

Jenny Eagle (January 19, 2016). “EFSA evaluates rPET chain extender substances to increase molecular weight.Food Production Daily