I've noticed that many glow-in-the-dark objects you can purchase in the store are green. Occasionally I would come across something that was orange or blue, but mostly it seems that green is the ubiquitous glow-in-the-dark color.

Does this have anything to do with common wavelengths of light emitted from the relaxing of electrons in some of the more common phosphorescent compounds? Are some phosphorescent compounds just more readily available or "safe" for use in toys?