Asthma caused by metal carbides or hard metals

  • Diamond working
  • Glass industry
  • Metallurgist
Cobalt, Nickel, Tungsten.
Incidence: directly proportional to the exposure to the risk. Subjects are often atopic. An IgE-dependent mechanism has been demonstrated for some metals. The most useful of the metal carbides are: cobalt, tungsten, titanium and tantalum. Cobalt has been the most widely studied and in this case the pathology of the metal carbides is identical to the occupational allergy to cobalt dust. A cross reactivity may exist between cobalt and nickel.
All work in which these carbide dusts may be inhaled (e.g. mixture of powders) is dangerous. All the surrounding work areas are also likely to be exposed. In the glass industry, the greatest risk occurs when powders are mixed.
Rhinitis, coryza, spasmodic cough and dyspenoea. These symptoms may be complicated by concurrent bronchial obstruction which may manifest functional changes due to alveolitis and/or fibrosis. In 2001, a case of severe cardiac arrhythmia was reported in a diamond polisher, who had continued in his work for economic reasons despite being diagnosed as suffering from occupational asthma. It was suggested that there was a cause and effect relationship between the cardiac disease and the length of exposure.
Diagnostic methods
Skin tests are not used in current practice. Tests have been carried out using CoSO4. Skin prick tests were negative and IDR tests positive at a concentration of 10 mg/ml.
A bronchial provocation test (in hospital) is the only diagnostic method for Co. The bronchial response may be immediate or delayed.


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As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.