I've lost many chips (jetons) and plaques to polyvinyl compounds (flips, stock books, large binder pages) over long term storage. Red clay composition also suffers when in contact with PVC. The chips and plaques I've lost can never be replaced. Reaction resulted in size and shape deformations and color loss. Also, depending on the composition of the piece: either the piece or the PVC will breakdown. I know very little about PVC or chemistry, but I do suggest a search for those who are interested in learning its hazards.

JB