Lead might have been in some of the paints. You say it lasted into the 1950s, so it would have been active during the early 20th century when they did have lead in paints.

I'd suggest doing an internet search on "Chemicals in Paint" or Adhesives or Lacquers.

It'll give you more than you EVER wanted to know.

I agree that the casting would not likely have been done on-site. Where are you located?