The word cadmia, and thus cadmium, descends from Cadmus, the hero of Greek legend who founded the city of Thebes. Cadmus, sent to find his sister Europa after her abduction by Zeus, instead slew a dragon and sowed its teeth, from which sprang armed men; he is also credited in myth with bringing the alphabet to Greece. His name became attached in antiquity to certain earths and ores of the Thebes region, calamine among them, and so passed, by a long thread, to the metal Stromeyer drew out of zinc ore. The connection is etymological rather than symbolic, but it lends this modern, toxic metal a surprising descent from one of the founding heroes of Greek myth. Cadmium yellow later became a treasured pigment of painters.
Cadmium's industrial retreat accelerated after the European Union's RoHS directive, adopted in 2003 and in force from July 2006, restricted the metal, along with lead and mercury, in most electronic and electrical equipment, part of a broader regulatory response to the same toxicity that caused itai-itai disease. Nickel-cadmium batteries, once the standard rechargeable technology in cordless tools and electronics, have been steadily displaced by nickel-metal-hydride and lithium-ion chemistries, partly for environmental reasons and partly because NiCd cells suffer a well-known memory effect that gradually reduces their usable capacity if repeatedly recharged before fully discharged.