ENVIRONMENTAL BIOLOGY AND PATHOPHYSIOLOGY OF CADMIUM

Cadmium (Cd) is a soft, silver-white metal being together with zinc and mercury in group II b in the periodic table. It's melting and boiling point are 320.9 0 C and 765 0 C, respectively. Cd is rapidly oxidized into cadmium oxide in the air. When reactive gases such as carbon dioxide, sulphur dioxide, sulphur trioxide and hydrogen chloride or water vapour are present in the air, cadmium vapour reacts to produce cadmium carbonate, cadmium sulphite, cadmium sulphate, cadmium chloride or cadmium hydroxide. These compounds may be formed in chimneys and emitted into the environment. It is indicated that zinc-bearing coals of the central United States and carboniferous age coals of other countries contain large sub economic resources of cadmium. Although some cadmium compounds such as acetate, chloride and sulphate are soluble in water; cadmium oxide, carbonate and sulphide are insoluble.