ABSTRACT
This chapter provides a detailed discussion on the occurrence and production, uses, chemical and physical properties, exposure and exposure limits, toxicokinetics, and effects of hafnium in humans. The crustal abundance of hafnium is 5 ppm. Hafnium is found in all zirconium minerals. It is removed from zirconium only for nuclear applications since hafnium has a much greater thermal neutron capture cross section than Zr. Hafnium is used for control rods in water-cooled reactors, light bulb filaments, electrodes, and special glasses and as a getter in vacuum tubes. It accompanies all exposures to zirconium except any that might be due to the Zr alloys used in the nuclear industry. The effects of hafnium in humans include information on acute toxicity, chronic toxicity, biochemistry, specific organs and systems, teratogenicity, mutagenicity, and carcinogenicity.
