Tungsten

This chapter provides a detailed discussion on the occurrence and production, uses, chemical and physical properties, exposure and exposure limits, toxicokinetics, and effects of tungsten in humans. Tungsten is found worldwide in various tungstate minerals. The commerical ores are wolframite, (Fe, Mn)WO₄; scheelite, CaWO₄; ferberite, FeWO₄; and huebnerite, MnWO₄. The concentrated tungstate is reduced with hydrogen or carbon to obtain the pure metal. The largest use of tungsten is conversion to tungsten carbide (WC) for use in cutting and wear-resistent materials. Other uses include alloys, especially for high-strength alloys, incandescent lamp filaments, and compounds used as pigments, catalysts, analytical reagents, and other uses. The effects of tungsten in humans include information on acute toxicity, chronic toxicity, biochemistry, specific organs and systems, teratogenicity, mutagenicity, and carcinogenicity.