Heavy metal ions in glass and related legislation

Within the framework of the measures taken to regulate the use of toxic heavy metals the recent EC Directive 94\62, of environmental concern, and the revision of the International Standard ISO 7086, of more specific food safety concern, are playing a very significant role. The compositional limits for heavy metals set up by the Directive on packaging and packaging waste are not really relevant to the aim of preventing feachingfrom glass because of the inherent inertness of the glass as a material. On the other hand it may discourage recycling which is a main objective of the Directive. An overview on the typical contamination occurring for glass bottles available on the market is given, together with the corresponding migration levels. The new limit values proposed by ISO 7086 for the migration of lead and cadmium from food articles can easily be fulfilled by lead bearing glasses providing there is careful control over the chemical composition. A regression analysis carried out on a large set of lead crystal glasses enables us to predict the chemical durability of a glass related to the required viscosity and workability.