Cadmium is a highly toxic metal. Dust of cadmium or its compounds is very dangerous and can kill. Some countries have banned cadmium from electronics. Cigarette smoking is the most important source of cadmium. Smokers have about 4 times more cadmium in their blood than nonsmokers (people who do not smoke). Cadmium is thought to be carcinogenic, although people still debate whether it is other things with the cadmium that cause cancer, like arsenic.