Just found a link to this article over on the Melting Pot. Its a very interesting read and talks a lot about the metals left on the surface art glass beads especially if they have been reduced. I've not had a chance to read through it properly but it seems to call for makers of art glass rods etc to be more open about their recipes, giving the artist and consumer a better knowledge of the medium they use and the saftey implications which go with this.
Starts on Page 28!
http://content.yudu.com/A1ot70/MTO18Issue5/resources/index.htm?referrerUrl=http%3A%2F%2Fwww.microscopy-today.com%2F (http://content.yudu.com/A1ot70/MTO18Issue5/resources/index.htm?referrerUrl=http%3A%2F%2Fwww.microscopy-today.com%2F)