Toxicometallomics for research on the toxicology of exotic metalloids based on speciation studies

Tellurium and antimony are widely used in industry because of their unique chemical and physical properties. Although these metalloids, which belong to period 5 of the periodic table of elements, are known to be non-essential and harmful, or the so-called "exotic" elements, little is known about their toxic effects and metabolism. The present review describes the role of speciation in considering the metabolism of tellurium and antimony from the viewpoint of toxicometallomics. Inorganic tellurium in the form of tellurite is reduced and simply methylated in the body. Rat red blood cells accumulate tellurium in the form of dimethylated tellurium, and tellurium is excreted into urine as trimethyltelluronium. Although selenium, which belongs to the same group as tellurium, is known to be excreted in the form of selenosugar as the major urinary metabolite, tellurosugar was not detected by an inductively coupled plasma-mass spectrometer hyphenated with an HPLC. Speciation studies revealed that the major metabolic pathway of antimony is oxidation in human and rat, and methylation also occurs as a minor metabolic pathway in humans.