Yttrium [Y, 39]

Yttrium (Y), a silvery transition metal of group 3 in the periodic table of elements, is chemically similar to lanthanides, and often classified as a rare earth element. Yttrium has no known biological role, and exposure to its compounds can cause lung disease in humans. Worldwide Y content of soils is estimated to be about 15 mg/kg, within the range between 2 and 100 mg/kg. Atmospheric dust contains Y within the range of 0.2–2 mg/kg. Yttrium contents of higher plants vary considerably, mainly from 0.01 to 3.5 mg/kg, depending on soil and climatic factors. Yttrium content in the human body is estimated to be 0.5 mg. It may bind weakly to various organic ligands and may compete for the binding sites of some other elements. Water-soluble compounds of Y are considered mildly toxic, whereas its insoluble compounds are nontoxic. ⁹⁰Yttrium is one of the most useful radioisotopes in the development of antibody-based radioimmunotherapy.