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A literature search provided information on known breakdown products of the curatives and antidegradants listed in the CoE Rubber Resolution. This included information on the curative blends used in commercial food contact rubbers. This information was supplemented with theoretical predictions of reaction/breakdown products.
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In order to assess the accuracy of these predictions, 19 food contact rubber 'compounds' were manufactured. Test sheets were cured from these 'compounds' and some of these sheets were aged under industry standard conditions to ensure that the antidegradants had broken down. The breakdown products present in these aged and unaged test sheets were then identified using both headspace and solvent extraction gas chromatography-mass spectrometry (GC-MS).
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Migration studies were performed on 10 of the test sheets using worst case time and temperature contact conditions. Ethanol was used as a fatty food simulant and the migrants identified and semi-quantified using GC-MS. Aqueous simulants (3% acetic acid, 15% ethanol and water) were analysed by liquid chromatography-mass spectroscopy (LC-MS). Migration work was also undertaken using some food products (whisky, white wine, beer and olive oil), again using worst case contact conditions and GC-MS.
Elastomeric rubber products are used in a variety of food contact situations under different conditions. An inventory list of substances added to food contact elastomers during their production has been compiled by the Council of Europe (CoE). The list does not take into account the fact that two of the major classes of substances, curatives and antidegradants, will undergo reactions during the processing and service life of the rubber products.
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Curatives may undergo several reactions during vulcanisation (i.e. curing), using up the majority of the original curative. Antidegradants, which protect the rubber from degradation, will undergo reactions depending on the service conditions. Therefore, it will not just be the original compounds that have the potential to migrate into food, but also the breakdown products of these reactions. The majority of these reaction/breakdown products will have relatively low molecular weights so their migration potential may be high.
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The primary objective of this project was to provide as comprehensive a list as possible of the breakdown/reaction products that may originate from the curative and antidegradant compounds given in the CoE Rubber Resolution. Some work was also carried out using food simulants and food products to assess the potential of these breakdown/reaction products to migrate into food.
<p>Find more about this project and other FSA food safety-related projects at the <a href="http://www.food.gov.uk/science/research/" target="_blank">Food Standards Agency Research webpage</a>.