As Gamblin artist paints explain: The cadmium used in artists paints is a different form, chemically bound with sulfur so it is stable. It almost seems like it should be called something different to keep people from getting it confused with cadmium metal.
Cadmium pigments are actually made from cadmium compounded with sulfur for the Cadmium yellows (sulfur and zinc for Cadmium Lemon and Cadmium Yellow Light). To make Cadmium reds and Cadmium oranges, Cadmium is compounded with sulfur and selenium.
American manufacturers of cadmium pigments have developed production systems that yield cadmium pigments that are relatively insoluble in the human digestive system. They have been so successful that Gamblin Cadmium oil colors DO NOT REQUIRE an ASTM health warning label for ingestion.