Platinum Group Elements: Palladium, Iridium, Osmium, Rhodium, and Ruthenium

The platinoid metals (interchangeably referred to as the platinum group elements [PGE] or platinum group metals [PGM]) include palladium, iridium, osmium, rhodium, and ruthenium, and can be found together in nature in various concentrations. This chapter discusses the uses, physical and chemical properties, bioaccumulation, ecotoxicology and mammalian toxicology, sources of exposure, and industrial hygiene of PGE. Members of the PGE share similar physical and chemical properties with each other, including their ability to resist corrosion. Much like platinum, PGE have the potential to sensitize exposed individuals, with degree of toxicity depending on the exact metal and solubility. Palladium compounds have a low to moderate acute oral toxicity and the toxicity depend on their solubility. Iridium, palladium, and ruthenium/rhodium radioisotopes are used in brachytherapy to treat certain forms of cancer, including prostate, breast, and ocular.