Tellurium

Tellurium is a chemical element with symbol Te and atomic number 52.

Uses

Tellurium is used as a coloring agent in ceramics.
Tellurium is also used in the electronics industry, for example with cadmium and mercury to form photosensitive semiconductors. Cadmium telluride (CdTe) is used as a thin film in solar panels to convert sunlight into electricity. CdTe panels have an efficiency rating of between 11 and 13 percent compared to amorphous silicon solar panels which have an efficiency of between 7 to 9 percent.
It is used in vulcanizing rubber and in catalysts for petroleum cracking and in blasting caps for explosives.

Tellurium has no known biological function, although fungi can incorporate it in place of sulfur and selenium into amino acids such as telluro-cysteine and telluro-methionine. Organisms have shown a highly variable tolerance to tellurium compounds. Many bacteria, such as Pseudomonas aeruginosa, take up tellurite and reduce it to elemental tellurium, which accumulates and causes a characteristic and often dramatic darkening of cells. In yeast, this reduction is mediated by the sulfate assimilation pathway. Tellurium accumulation seems to account for a major part of the toxicity effects. Many organisms also metabolize tellurium partly to form dimethyl telluride, although dimethyl ditelluride is also formed by some species. Dimethyl telluride has been observed in hot springs at very low concentrations.

Tellurium and tellurium compounds are considered to be mildly toxic and need to be handled with care, although acute poisoning is rare. Tellurium poisoning is particularly difficult to treat as many chelation agents used in the treatment of metal poisoning will increase the toxicity of tellurium. Tellurium is not reported to be carcinogenic.Humans exposed to as little as 0.01 mg/m³ or less in air exude a foul garlic-like odor known as “tellurium breath.” This is caused by the body converting tellurium from any oxidation state to dimethyl telluride, (CH₃)₂Te. This is a volatile compound with a pungent garlic-like smell. Even though the metabolic pathways of tellurium are not known, it is generally assumed that they resemble those of the more extensively studied selenium because the final methylated metabolic products of the two elements are similar.
People can be exposed to tellurium in the workplace by inhalation, ingestion, skin contact, and eye contact. The Occupational Safety and Health Administration (OSHA) limits (Permissible exposure limit) tellurium exposure in the workplace to 0.1 mg/m³ over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set the recommended exposure limit (REL) at 0.1 mg/m³ over an 8-hour workday. In concentrations of 25 mg/m³, tellurium is immediately dangerous to life and health

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Te, atomic number 52