Zirconium is a chemical element with symbol Zr and atomic number 40. It is a lustrous, grey-white, strong transition metal. Zirconium is mainly used as a refractory and opacifier, although it is used in small amounts as an alloying agent for its strong resistance to corrosion. Zirconium forms a variety of inorganic and organometallic compounds such as zirconium dioxide and zirconocene dichloride, respectively. Five isotopes occur naturally, three of which are stable. Zirconium compounds have no known biological role.
Short-term exposure to zirconium powder can cause irritation, but only contact with the eyes requires medical attention. Persistent exposure to zirconium tetrachloride resulted in increased mortality in rats and guinea pigs and a decrease of blood hemoglobin and red blood cell in dogs.
Zirconium is not considered an industrial health hazard. Reports of zirconium-related adverse reactions are rare and, and in general, rigorous cause-and-effect relationships have not been established. There is no evidence that zirconium is carcinogenic or genotoxic.