Within the general task of evaluating substances intended for use in materials in contact with food according to the Regulation (EC) No1935/2004 of the European Parliament and of the Council of 27 October 2004 on materials and articles intended to come into contact with foodstuffs, the CEF Panel received a request from the Ministry of Health, Welfare and Sport, the Netherlands for safety assessment of the substance 5-norbornene-2,3-dicarboxylic anhydride following a corresponding application submitted on behalf of Valspar Packaging Corp AG, Switzerland.
The safety assessment of 5-norbornene-2,3-dicarboxylic anhydride with the CAS No 826-62-0 and the FCM substance No 978 was requested for use as a co-monomer in polyester based coatings for metal cans at levels up to 8.7 wt % of the wet coating formulation which equates to 18.3 wt % in the final coating. The coated cans are intended for contact with all type of foods excluding beverages, for long term storage at room temperature including a preceding hot-fill or sterilisation at temperature of up to 131 °C.
The residual content of the substance in a double coat sample with an exaggerated coating area weight was determined using an exhaustive extraction with acetonitrile. From this, worst case migration calculated for total mass transfer of the two isomers of the substance and their hydrolysis products, the diacids was 27 µg/kg food. From the same experiment the overall migration was 24 mg/kg food. The low molecular weight fraction (molecular weight <1000 Dalton) was found to make up 8.8 mg/kg food, out of this the LMWF which contains the substance was 1.54 mg/kg food.
Based on negative results from two in vivo genotoxicity tests, the Panel considered that the substance its self and the oligomers with MW<1000 Da containing the substance moieties are non-genotoxic. The systemic toxicity of the 5-norbornene-2,3-dicarboxylic anhydride-containing oligomers <1000 Da was assessed in a subchronic (90 day) oral rat study. The synthetic oligomers used as a test substance in this study are representative for the oligomers extracted from a coating sample. The Panel derived a NOAEL from this study at 250 mg/kg bw/day based on lower body weights, lower thymus weights associated with lymphoid depletion and hypocellularity in the bone marrow in male rats at 500 and 1000 mg/kg bw/day. In addition it was noted that the thymus effects might be associated with immunosuppression.
However, based on the low exposure to the LMWF oligomers containing the substance of 25 µg/kg bw/d (resulting from a migration of 1.54 mg/kg food and assuming a default consumption of 1 kg food per day by an adult weighing 60 kg (EC, 2001)) the margin of safety (MOS) to the NOAEL is 10.000. This MOS is considered sufficient and therefore, does not raise a concern for immunosuppression.
Accumulation of the LMWF oligomers in the human body is not expected due to their inherent low lipophilicity.
The CEF Panel concluded that the substance 5-norbornene-2,3-dicarboxylic anhydride is not of a safety concern for the consumer if it is used as a co-monomer in polyester based can coatings at levels of up to 18.3 weight % of the final dry coating, in contact with all food excluding beverages, at sterilization conditions and long term contact. Migration of the substance and its hydrolyses products, the diacids, should in total not exceed 50 µg/kg food.