Tellurium [Te, 52]

Tellurium (Te), a silvery-white metalloid of group 16 in the periodic table of elements, is one of the rarest stable elements in the Earth’s crust. Today, most Te is obtained as a by-product of mining and refining copper. Tellurium minerals are also associated with iron, silver, and gold deposits. The worldwide mean Te levels in soils are given as 0.006 mg/kg. The general range of Te in soils, given for various countries, is from 0.02 to 0.5 mg/kg. Tellurium concentrations in surface waters range from 0.17 to 0.9 ng/L, being highest in the Red Sea. Plants uptake Te relatively easily and correlate positively with its contents in growth media. Tellurium content in humans (70 kg) is estimated to be 0.7 mg. Organotellurium compounds, with reasonably stable Te–carbon bonds, are generally considered as less toxic, compared to inorganic, such as tellurate and tellurite. Tellurium nanoparticles can be used as antibacterial reagents against Escherichia coli.