Cadmium pigments are a class of pigments that have cadmium as one of the chemical components. They are highly toxic and can produce cadmium poisoning. The principal pigments are a family of yellow/orange/red cadmium sulphides and sulfoselenides. Cadmium yellow is cadmium sulphide (CdS); by adding increasing amounts of selenium, colours ranging from orange to nearly black (the colour of cadmium selenide) can be produced. Cadmium yellow is sometimes mixed with viridian to give a bright, pale green mixture called cadmium green.