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

Tungsten oxide, CAS number 39318-18-8, FCM substance No 1064, food contact materials, safety assessment, evaluation
First published in the EFSA Journal
13 January 2017
1 December 2016
Scientific Opinion

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).

Panel members at the time of adoption
Claudia Bolognesi, Laurence Castle, Jean-Pierre Cravedi, Karl-Heinz Engel, Paul Fowler, Roland Franz, Konrad Grob, Rainer Gürtler, Trine Husøy, Sirpa Kärenlampi, Wim Mennes, Maria Rosaria Milana, André Penninks, Vittorio Silano, Andrew Smith, Maria de Fátima Tavares Poças, Christina Tlustos, Detlef Wölfle, Holger Zorn and Corina-Aurelia Zugravu.
Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids
fip [at]
EFSA Journal 2017;15(1):4661
Question Number
On request from
Food Standard Agency, UK

The full opinion will be published in accordance with Article 10(6) of Regulation (EC) No 1935/2004 once the decision on confidentiality, in line with Article 20(3) of the Regulation, will be received from the European Commission. The purity of the substance has been provided under confidentiality and it is deleted awaiting the decision of the Commission