Typically, the toxicity of metals depend on how they're structured within molecules. For example, inorganic copper is cytotoxic, while organic copper is necessa

Typically, the toxicity of metals depend on how they're structured within molecules. For example, inorganic copper is cytotoxic, while organic copper is necessary for survival. In this case, the yttrium blue has a unique chemical structure. More so, I believe they use Manganese oxide to create the color. Manganese oxide is not dangerous, as far as we know, at least. It's a somewhat common food additive. According to [wikipedia](https://en.wikipedia.org/wiki/Manganese(II)_oxide https://en.wikipedia.org/wiki/Manganese(II)_oxide), we consume tons of it per year. Ultimately, what typically matters is how a molecule interacts with the body, not necessarily how each component interacts. By that measure, Cyanide (which is just carbon + nitrogen) ought to have no ill effect, while cuprous oxide ought to be poisonous.