[Pulmonary pathology due to cobalt and hard metals]

For forty years, cases of interstitial pneumonia and bronchial asthma have been described in hard metal workers (i.e., alloys of tungsten carbide and cobalt). Recently we have reported comparable pulmonary lesions in workers in the diamond industry who were exposed to cobalt unassociated with tungsten carbide. The exposure came from the diamond cobalt discs used for polishing diamonds, which had as the hard element microdiamonds, cemented in an alloy of pure cobalt. The hard metals on the other hand consisted of cobalt and tungsten carbide. Forty-seven diamond cutters (i.e., nearly 1% of those exposed) presented with broncho-pulmonary pathology due to cobalt. Nineteen had a fibrosing alveolitis, sometimes documented by a pulmonary biopsy and more often by a broncho-alveolar lavage which revealed characteristic multinucleated giant cells. Thirteen had occupational asthma, often proved by specific inhalation provocation tests to cobalt or by lung function measurements at the place of work. Two patients had mixed forms and in thirteen a probable diagnosis was suggested. The pathogenesis of cobalt might be explained by cytotoxic action such as has been demonstrated in animal experiments. Either results suggest a sensitising or allergic action. Tungsten carbide does not produce pulmonary lesions but its association with cobalt intensifies the effects of the latter.