Cobalt lung in diamond polishers

Five diamond polishers with interstitial lung disease attributed to cobalt not alloyed to carbides of hard metals are described. The exposure originated from high-speed grinding tools with a polishing surface of microdiamonds cemented in very fine cobalt. Mineralogic analysis of lung tissue, lavage fluid, filtered air, and exhaust dust in the work environment revealed cobalt as the only toxic agent. Complaints consisted of work-related rhinitis, cough, chest tightness, dyspnea, anorexia, and weight loss, and were intensified in the absence of an adequate exhaust ventilation. Three subjects were in a rather subacute stage, as documented by open lung biopsy in 2 of them, and had a severe restrictive defect and markedly decreased diffusing capacity. Two patients presented a more chronic histologic pattern and had a less decreased diffusing capacity. Open lung biopsies showed in these 4 a fibrosing alveolitis, mainly of the centrilobular zones. In the former 2 patients, subacute lesions consisting of a mural mononuclear cell infiltrate, marked intra-alveolar desquamation, and multinucleated giant cells were found, whereas in the latter 2, centrilobular fibrosis with some microcyst formation was also already seen. Multiple multinucleated giant cells were present in the bronchoalveolar lavage fluid. Interruption of the exposure, with or without corticotherapy, caused a rapid regression of the complaints and a partial improvement of lung function.