Cadmium is a chemical element with the symbol of Cd with the atomic number of 48, it is usually a byproduct of zinc mining, and it is quite poisonous as well, along with lead, arsenic, and other heavy metals. It behaves similar to zinc by oxidizing, and this stable metal is bluish, and mostly grey, but it is stable in the group 12 classification of the periodic table, like lead and mercury, and the average concentration of cadmium in the earth's crust is 0.1%.
It is not considered a transition metal, along with it's congeners in the group 12 classification. It was discovered as an impurity in zinc carbonate.
Cadmium exposure can be extremely dangerous, cadmium is classified as a heavy metal, so it is incredibly poisonous. One of the only efficient ways to get it out of a bloodstream is a chelation therapy, which includes using a material to bond to the heavy metal and filtering it out of the blood repeatedly. The same applies to other heavy metals such as lead, mercury, arsenic, chromium, and thallium.