LUNG CONTENT-ANALYSIS OF CASES OCCUPATIONALLY EXPOSED TO CHRYSOTILE ASBESTOS

The lung contents of six workers who had been occupationally exposed t o chrysotile asbestos were examined. Five were lung cancer cases from Quebec, Canada. The sixth, an American worker who had developed pleura l mesothelioma, was particularly interesting. with the lung content st rikingly distinct from the Canadian cases; chrysotile, the predominant fiber in his lung, was present at a concentration 300 times that of t he average total fiber content in the Canadian cases. The fiber length distribution of the chrysotile recovered from the U.S. mesothelioma c ase was indistinguishable from that of chrysotile specimens known to p roduce mesotheliomas in rats. It was also found that the characteristi cs of the calcium-magnesium-iron silicate fibers present in atl six ca ses were not readily comparable to tremolite asbestos specimens known to induce mesotheliomas in animals.