Cobalt poisoning
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Cobalt poisoning is the intoxication which takes place when the levels of cobalt or a compound containing cobalt inside an animal increase to levels that are unsafe. Cobalt naturally occurs in animals in minute amounts and forms part of the structure of Vitamin B12 without which animals cannot live. However, when levels increase beyond a safe limit, cobalt is highly toxic and can cause death. Cobalt poisoning is less dangerous than Lead Poisoning because unlike Lead, cobalt is excreted by the body.
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[edit] How cobalt enters the body
Cobalt can enter the body by ingestion, inhalation, injection, or through the skin.[1] The group of people most likely to be affected with cobalt poisoning are potters because cobalt blue is popularly used as a glaze.
[edit] Method of action
Hydroxyl radicals may form when cobalt ions interact with reactive oxygen species. Such cytotoxic free radicals may then cause the production of further free radicals which reduce cellular glutathione concentrations and NADPH activity. The resulting oxidative stress leads to DNA and cellular protein damage (Timbrell, 1994).
Cobalt is immunogenic and acts as a hapten in the induction of bronchial and dermal hypersensitivity (Sjögren et al, 1980). Ionized cobalt is an important contributing factor in the aetiology of hard metal lung disease. Evidence for an autoimmune mechanism in this disorder is suggested by the recurrence of disease in a single transplanted lung despite no evidence of cobalt in the donated organ (Frost et al, 1993). In cobalt pneumoconiosis, non-respiratory symptoms may be due to cobalt-induced release of a tumour necrosis factor from sensitized pulmonary lymphocytes (Rolfe et al, 1992).
In animal studies, cobalt decreases synthesis of several enzymes including cellular cytochrome P450 (Timbrell, 1994). Cobalt inhibits aminolevulinic acid synthase and increases the activity of haem oxygenase which breaks down haem to biliverdin (Taylor and Marks, 1978; Timbrell, 1994).
[edit] Cobalt poisoning lawsuits
There have been numerous legal cases where potters have attempted to sue manufacturers of glazes containing the pigment cobalt blue for inadequately warning them about the dangers posed by chronic exposure to cobalt[2]. In most circumstances, these have been unsuccessful because the potters have been unable to prove that the cobalt came from the glaze or they have been unable to establish negligence.
[edit] History
Extensive studies have been carried out into the effects of cobalt intoxication on the body. In the past cobalt chloride was used to treat anemia however several patients receiving cobalt therapy developed symptoms such as ataxia and palpitations the symptoms would often resolve when the cobalt was withdrawn. There were also deaths in Belgium resulting from beer to which cobalt chloride had been added[3] as a foam regulator; this illustrated the danger posed by cobalt as the doses the drinkers received were very low.
[edit] References
- ^ Welcome to the IPCS INTOX Programme
- ^ Ceramics Today - Cobalt - Article by Jeff Zamek
- ^ Cobalt chloride (UK PID)
