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Using the COE and BCF non-exhaustive list of substances as a starting point, this desk study has reviewed the chemical nature of the components of inks and their associated coatings used on the outer (non-food-contact) side of food packaging.
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The types of crosslinking chemistry involved have been reviewed and monomers, their addition products and by-products of polymerisation or degradation considered. The presence and role of various co-agents of cure such as initiators and catalysts have also been considered. Classes of compounds covered included solvents, pigments, and dyes and extenders.
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Potential impurities and component reactivities of the listed substances have been studied, in order to examine the wider possibilities for potential migration. A detailed review of the literature for published information was carried out and five factory visits undertaken to provide first hand insights into the materials and processes used to bring greater industrial relevance to the technical review.
The aim of this research project was to assess the migration potential of substances, including reaction and breakdown products, from inks and coatings used in food contact applications. The core legislation controlling food contact materials and articles, European Regulation (EC) 1935/2004 provides for specific measures to be adopted for particular groups of materials and articles. Among the groups listed are printing inks, varnishes and coatings, although as yet there are no such specific measures for these materials. The Council of Europe (CoE), which is a non-legislative international organisation, separate from the European Community, has published a resolution on printing inks AP(2005)2. This Resolution includes a list of substances used for the manufacture of packaging inks (Technical Document No.1). The British Coatings Federation (BCF) is also developing up-to-date lists of substances currently being used by Industry for inks and their associated binder resins and over-print lacquers.
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As part of the management and analysis of these lists for future EU controls, it will be necessary to identify substances which are likely to migrate, and if so, under which conditions of food contact. As printing inks can be reactive, substances other than the starting materials may be present in the finished article and could also migrate into food. Thus impurities, reaction and breakdown products require detailed consideration.
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Drying (curing) mechanisms for inks and their coatings increasingly rely on reactive systems. Monomers and initiators used in printing have already been the subject of migration studies. For example, migration data on the UV cure initiators ITX (2-isopropylthioxanthone) and benzophenone have been published. Migration of low levels of aromatic amines from azo dyes and pigments has also been reported.
<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>.