Pneumoconiosis due to graphite dust.

Lassar Dunner (1945a) recorded the clinical and radiological findings in five men who had been exposed to " pure graphite " dust. They had been exposed for 17, 18, 20, 20, and 34 years respectively, and no other dusts were known to have been implicated. Three of the men had cough, sputum, and dyspnoea; the other two had no complaints. Radiographs showed reticulation with nodulation, and the question was raised in correspondence (Dunner, 1945b) whether there was a tissue reaction consistent with pneumoconiosis. Dunner believed that there was, and in later publications (Dunner and Bagnall, 1946; Dunner, 1948) described a form with a " snowstorm " appearance which became nodulated and in one case formed a cavity. It is doubtful, however, if such a thing as " pure graphite " exists commercially (except for manufactured varieties like " kish ") because, as explained by Dassanayake (1948), graphite is mined from vertical lodes in granite rock, and the miners develop similar lung changes to those found in metalliferous miners. The two fatalities here recorded followed long exposure to a mixed dust of graphite, free silica, various silicates, and possibly other substances used in the manufacture of crucibles. The hazard was not strictly comparable with Dunner's cases, therefore, but was more like that of coal-miners, judging from King and Nagelschmidt's (1945) analyses of dusts extracted from the dried lungs of South Wales coal-miners. There they found both free silica (quartz) and silicates (mica and kaolin) mixed with the coal. In our cases coal was replaced by graphite.