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Twenty-seven metalware items covering a range of cookware, kitchen tools and gadgets for use in the home were purchased from retail outlets and the metals present in their outer layer were identified. From these, nine products were selected for the migration studies. These included tin, chromium and nickel-containing products. The migration of metal ions into foods on single and repeat use (with scouring between use) was recorded. The foodstuffs and exposure conditions to which the metalware articles were exposed depended on the use of the product. For each application the most acidic food that the product may be exposed to and the worst foreseeable conditions of use were investigated.
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Results were compared with migration into a range of potential simulants; acetate buffers pH 3.5-6.0, citrate buffers pH 4.0-6.5, phosphate buffers pH 3.0-8.0, water, aqueous acetic acid (3 and 4 per cent), aqueous citric acid (3 and 4 per cent) and aqueous phosphoric acid (0.1 per cent). The most appropriate simulant (i.e. the one whose use led to the best estimate of migration) was selected from the data obtained. This allowed recommendations for testing metalware food articles to be derived.
Metal products, such as pans and trays, used in the kitchen may be covered with a layer of metal or non-stick coating. Metal layers are applied by either electroplating or dipping. During use of the metal-coated utensils or cookware, metals can migrate into food. The conditions of use will influence the levels of metal migrating. For example, more migration may be observed when the article is exposed to an acidic foodstuff (metal ions will be most soluble in acidic foods). Longer contact times and higher exposure temperatures will also result in increased migration. Currently no migration tests are recommended for these food contact materials.
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The testing of plated articles has long posed a problem to laboratories as there is no defined methodology for this class of food contact materials. In general testing is carried out into either 3 per cent acetic acid, as recommended to test plastics in contact with acidic foods, or 4 per cent acetic acid as recommended to test for metal release from ceramics. One aim of this project was to establish whether or not acetic acid is a suitable simulant for metalware products (in that it closely approximates or over-estimates migration into food), or if other simulants are more suitable. Another objective was to make recommendations that would provide a sound basis for the development of a protocol to test metalware for potential metal release (migration) to foods. Combinations of simulants and exposure conditions (e.g. time, temperature, number of exposures) were studied in order to obtain a reliable indication of the migration (which metals and at which levels) that may be expected to occur into foods.
<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>.