RELEASE OF METALS FROM CERAMIC ARTICLES IN CONTACT WITH FOOD: EFFECTS OF SIMULANT, PH, TEMPERATURE, CONTACT DURATION AND MIGRATION TIMES

摘要

Directive 84/500/EEC (a regulation which specifies migration limits of lead (Pb) and cadmium (Cd) from ceramic articles intended to come into contact with food), is currently under revision by the European Commission, both for defining new Specific Migration Limits (SMLs) for Pb and Cd and for considering an extension to other elements, with validated testing methods. In this study, we investigated how much various parameters (nature of acid as simulants, pH, temperature, contact duration and repeated exposure) influence the release of metals from decorated ceramic articles during their use. The amounts of a series of 17 elements (including lithium, aluminium, chromium, barium, lead and cadmium) leaching from ceramic articles were measured simultaneously by ICP-OES. For each piece of ceramic vessel under testing: (1) the amounts of metals released rose with a decrease in pH (in the range-2.05-2.97) in a non-linear mode, but this growth will not continue as much as the rise of the amount of hydrogen ions; (2) The amounts decreased with the repeated migration tests. Detailed studies of migration kinetics and behaviour at three temperatures (20°C, 40°C and 60°C) confirmed a rise with longer contact time, according to a logarithmic curve. Our data indicate that it is necessary to revise the Directive beyond the case of Pb and Cd, and to define SMLs for the potential migration of a series of metals. The test conditions with respect to all the parameters studied are discussed.