Exposure of diamond polishers to cobalt

Interstitial pulmonary fibrosis due to 'hard metal' exposure is well known, and the presence of cobalt has always been considered as the causative factor. Recently interstitial pulmonary fibrosis has been described in diamond polishing workers. In this study the dust composition in different polisher's workplaces where diamond disks are in use has been determined. Careful investigation showed that the exposure to respirable dust was comparable to that of 'hard metal' workers. The dust consists mainly of iron and cobalt particles and small amounts of silica. No 'hard metals' have been found, and other fibrogenic agents such as beryllium have been excluded. These observations lend support to the hypothesis that crystalline cobalt particles can be responsible for pulmonary fibrosis even in the absence of carbides.