Cadmium and sewage sludge This essay concentrates on the heavy metal cadmium, and its occurrence in the environment, its pathways into and out of the human body and its movement into and out of Sewage sludge. Firstly, I will provide a clear definition of the Heavy Metal Cadmium. Cadmium is a naturally occurring element in the earth’s crust. Pure cadmium is a soft silver-white metal, but this form is not common in the environment. Rather, cadmium is most often encountered in combination with other elements such as oxygen (cadmium oxide), chlorine (cadmium chloride), or sulphur (cadmium sulphide). These compounds are all stable solid