Thanks, Adam A. for pointing me to this thread which I would have missed otherwise.
By coincidence in the last few days I was asked about the use of arsenic and this is what I said:-
"Re arsenic, it most certainly was used, and probably still is in huge quantities. “Arsenic” or “white arsenic” are really arsenious oxide. We bought ours in, I think, 2 ton lots. 4 or 5 lbs in around a ton of glass would be quite common. The main (alleged) benefits are helping control colour, especially in 'colourless' compositions and improving melting rates. Quite a lot would go up the chimney to be spread around the neighbourhood. There is, of course, no danger at all from the finished glass. The arsenic, like everything else, is securely locked in. It came in small, strong barrels (it was extremely dense) and I remember my mixing room crew using an empty as a table for their sandwiches!"
You will see that I assumed that it was still widely used. Maybe I was wrong - I have no contacts in the industry now. Although the hazards to the workers are obvious I would have hoped that, in the glass industry at least, common sense would have prevailed.
It is 13 years since I retired from my second career as a Health and Safety Inspector. I am sickened by the way, since then, "health'n'safety" has been used as an excuse for the most outrageous assaults on common sense.