admium is a metal that has several modern applications, including some dyes, certain types of batteries and electronics, some plastics and paints and in the protective coating applied in steel and iron manufacturing. Even at a low dose, it is extremely poisonous to humans. Cadmium was discovered in 1817, but widespread use didn’t occur until the early 20th century. Around this time in Japan, cadmium contaminated the water in a river basin. It was released into the water as a byproduct of mining concerns.