One of the most interesting bits of trivia I've learned while picking up painting is that certain pigments are unavailable today or rapidly disappearing.
Some of these are:
Genuine Lead White (a.k.a. Cremnitz or Flake White) is bobbling along on this area: it's a health risk, but not a significant one unless you have small children. The Cadmium family (reds through yellows) is under attack in the EU. It is largely safe unless you ingest the dust... then it's a big problem. Fortunately, that's rare. Unfortunately, Lead White and Cadmium have paint properties unavailable in their less toxic cousins, so if these get
A nifty business idea for a chemist would be to to try to haul out lists of the pigments from different times and determine which ones would be useful today with modern chemical knowledge, then produce & sell the pigments at a suitably boutique price. Specific ones from the above list that would retain significant interest would be Ultramarine Green and the Quinacridones, since they are non-toxic and colorfast.