Tellurium (Te)

For over a century, the ingestion of tellurium compounds has been known to be associated with a garlic-like odor of the breath, thus indicating that tellurium is absorbed by the gut, metabolized by tissues, and excreted through routes other than the feces. Other research has confirmed that homeostatic mechanisms for tellurium exist in animals and humans. Using sodium tellurite labeled with tellurium-127m (127mTe), Weight and Bell obtained findings indicating that 24% of the dose was absorbed from the colon in sheep and swine. They found urinary excretion was about three times fecal excretion when sodium tellurite was administered intravenously. The ratio was reversed following oral administration. Barnes et al. found the ratio of fecal to urinary excretion was 15 and 12 upon the oral administration of tellurium to guinea pigs and rats, respectively. De Meio and Henriques found that tellurium, as [121Te]sodium tellurite administered intravenously, appeared in the bile in addition to the urine. Schroeder et al. reported that the tellurium concentration in normal human urine was 0.63 mcg/ml.

In his review of tellurium, Klevay presented evidence that animals can synthesize dimethyltelluride.

The toxicity of orally administered tellurium is relatively low. When fed 375-1500 mcg of elemental tellurium per gram of diet for 21 days, rats developed a garlic odor in their breath, viscera, and urine but showed no pathological changes; in addition, those fed 375 and 750 mcg tellurium as Te02 per gram of diet developed redness and edema of the digits, temporary paralysis of the hind legs, and a loss of hair. Soluble tellurite or tellurate salts were toxic at concentrations of 25 to 50 mcg/g diet. Van Vleet observed a marked decrease in blood glutathione peroxidase over the last 6 weeks of a 10-week trial in pigs fed 500 mcg tellurium as the tetrachloride per gram of diet. This level of dietary tellurium also increased the incidence of vitamin E-selenium deficiency type signs of necrosis of cardiac and skeletal muscle. On the other hand, Whanger and Weswig reported that 10 mcg tellurium, as Te02 per gram of diet did not enhance liver necrosis in selenium-vitamin E deficient rats. Instead, tellurium apparently increased the life span of the rats. Whanger and Weswig suggested that decreased food consumption might have been partially responsible for the increased life span.