Cobalt

Cobalt is an essential element, being required for the synthesis of vitamin B12. The metal is used to make high temperature, high strength alloys and for the preparation of tough carbide-tipped cutting and drilling tools. Cobalt is also used in the manufacture of semi-conductors, magnetic alloys and catalysts. Cobalt salts are highly coloured and have been used from the earliest times for pigment production. Dicobalt edetate is used in the treatment of cyanide poisoning.

Deficiency
Vitamin B12 – cobalamin – contains cobalt and deficiency of this vitamin, causing pernicious anaemia, is due to failure of absorption from the diet through absence of the so-called intrinsic factor.
Cobalt deficiency per se is virtually unknown in man, although occurring in animals: an anaemia results from the inability of microorganisms in the gut of the affected animals to manufacture sufficient quantities of vitamin B12.

Toxicity
Inorganic cobalt causes increased production of haemoglobin and can induce hypertriglyceridaemia and hypercholesterolaemia. Cardiomyopathy has been seen in individuals with chronic ingestion.
Inhalation of cobalt-containing dust is a hazard in the manufacture and use of hard metal alloy tools, and causes interstitial lung disease with cough and dyspnoea.
Although several other elements such as tungsten, nickel, vanadium and chromium may be involved, this so-called “hard metal” disease is thought to be largely due to the toxic effects of cobalt. Cobalt dermatitis may occur but the condition is more likely from associated chrome or nickel.

Laboratory Indices of Exposure
Urinary cobalt concentrations provide a sensitive index of recent exposure. Concentrations increase throughout the working day and week but return from very high to basal levels within 2-3 days.

References:
Taylor A. Cobalt Carcinogenesis. In, Biological Effects of Heavy Metals. Vol II Carcinogenesis, ed, Foulkes EC. CRC Press, Florida, 1990, pp 159-171
Lison D, Buchet J-P, Swennen B, Molders J, Lauwerys R. Biological monitoring of workers exposed to cobalt metal, salt, oxides and hard metal dust. Occup Environm Med 1994; 51: 447-50

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