A study on lung toxicity of respirable hard metal dusts in rats.

The aetiology of hard metal lung disease has not been clarified so far. The pulmonary toxicity of respirable dusts collected in a hard metal factory was studied in vivo in rats. The effect of the samples was examined 1, 4, 7 and 30 days after single intratracheal injection. Lactate dehydrogenase (LDH), acid phosphatase (AP), protein and phospholipid were determined in cellfree bronchoalveolar lavage (BAL) and lung tissue. The lungs and regional lymph nodes were processed histologically. Lung toxicity of the samples collected during hard metal production varied. Samples containing considerable amount of cobalt dissolved upon acid treatment were found to induce inflammation. It has been established that the biological effect of samples of identical composition is changed by heat treatment and pre-sintering. Our examinations seem to prove that cobalt plays a prominent role in the development of pathological alterations.