COBALT AND POSSIBLE OXIDANT-MEDIATED TOXICITY

The occurrence of interstitial lung disease similar to hard metal lung disease in diamond polishers who had been exposed to cobalt (in the a bsence of tungsten carbide) through the use of polishing disks contain ing microdiamonds sintered with cobalt, led us to experimentally test the hypothesis that cobalt has pro-oxidant activity in lung tissue. Se veral experiments were carried out in which we measured indices of oxi dant stress, mainly changes in the oxidation state of glutathione and in the activity of the pentose phosphate pathway, upon exposure of ham ster pulmonary tissue to CoCl2 in vivo by intratracheal instillation, or in vitro by incubating lung slices. These experiments indicated tha t cobalt ions are capable of causing thiol oxidation in lung tissue as an early manifestation of oxidant stress, but more studies are needed to establish the relevance of this mechanism in the causation of lung disease in subjects exposed to cobalt-containing dusts.