Safety assessment of the substance ‘Tungsten Oxide’ for use in food contact materials

This scientific opinion of EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF Panel) deals with the risk assessment of the additive tungsten oxide, CAS No 39318-18-8 and FCM No 1064, for use in food contact materials as a reheat agent in polyethylene terephthalate (PET) at a maximum use level of 75 ppm (75 mg/kg PET). The substance is a mixture of tungsten oxides with tungsten at different oxidative levels. The average oxidation level of tungsten in the oxides is 2.86 corresponding to 19.93% oxygen content. Detailed information on impurities is provided as confidential. Specific migration from PET plaques with the substance at 150 mg/kg (double the maximum intended use level of 75 mg/kg) was determined into 95% ethanol, as a worst-case simulant for PET due to its swelling effect. Under these test conditions, the specific migration, measured as tungsten using ICP-MS, was at the level of 1 μg/kg. The Panel considered that due to the insolubility of the substance, this low migration will be typical for any foreseeable use as a reheat additive in PET. Two in vitro genotoxicity studies, a bacterial gene mutation test and an in vitro micronucleus assay, performed in accordance with the OECD Guidelines and in compliance with GLP, were provided by the applicant for the substance tungsten oxide and were considered negative by the CEF Panel. According to a scientific opinion on strategy for genotoxicity testing (EFSA, 2011), the three genotoxic endpoints, gene mutation, chromosomal and numerical aberrations, are covered by these two tests. The CEF Panel concluded that the substance tungsten oxide is not of safety concern for the consumer if the additive is used as a reheat agent in PET. For other technical functions or for use in other polymers, the migration should not exceed 50 μg/kg (expressed as tungsten).