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An investigation of the migration of metals from glazed ceramic ware
Project Code: A03016
Food and Environment Research Agency, Sand Hutton, York YO41 1LZ
Bradley, E ; Castle, L
The clays and particularly the coloured glazes used in the manufacture of glazed ceramic ware contain a variety of metals for which little information is available with regard to their potential for migration into food and drink. The aims of this project were:
· to establish compliance with current legislation for the migration of lead and cadmium into the simulant four percent acetic acid (Directive 84/500/EEC) from a range of ceramic articles;
· to identify which other elements migrate into this simulant: and,
· to establish the validity of the current method of test by comparison of the results
obtained using the simulant with those obtained for migration into foods under
‘normal’ and ‘worst foreseeable’ conditions of use.
Since this project was commissioned two draft international standards have been produced: ‘Ceramic ware, glass-ceramic ware and glass flatware in contact with food - Release of lead and cadmium - Part 1: Test method’ and ‘Part 2: Permissible limits
(Revision of ISO 6486-2:1981)’ which classify the products differently to Directive 84/500/EEC and give new migration limits for some of these product classes. One hundred and eleven products were purchased in duplicate and the elements migrating into the acetic acid were determined. Those products showing higher levels of metal ions leaching into the acetic acid solution were selected (n = 24) for further studies so that in total four test specimens of each article type were exposed to the acetic acid. The elements migrating at higher levels (by comparison with fifty times the median value) were Li, B, Mg, Mn, Co, Zn, Ga, Y, Mo, Ag, Cd, Ba, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Pb, V, Sb, Ni, Sr, Cs, Cu, Na and K. The products selected for further study showed elevated levels (greater than fifty times the median value) of some of these elements.
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