RETENTION OF ASBESTOS FIBERS IN THE HUMAN-BODY

The number, type, and size of retained asbestos fibers were measured b y scanning electron microscopy (SEM) in rung tissues of 10 workers who had died from lung cancer or mesothelioma. The levers were 190-3000 x 10(6) fibers/g of dry tissue in three crocidolite sprayers, 6-39 x 10 (6) fibers/g of dry tissue in two asbestos product workers and 13-280 x 10(6) fibers/g of dry tissue in five insulators exposed to anthophyl lite. The duration of past exposure corresponding to the limit of 1 mi llion fibers/g of dry tissue was 1 to 2 days in spraying, 3 to 10 days at the production plant and 1 to 4 months in insulation work. No long -term clearance of amphibole fibers, >5 mu m in length, could be demon strated. In one of the sprayers the fiber concentrations of lung paren chyma, visceral and parietal pleura, hilar lymph nodes, and kidney cor tex were orders of magnitude higher than in a series of unselected aut opsies. The size and aspect ratio of crocidolite fibers in various tis sues were similar, indicating that the translocation processes are rat her unselective in respect to fiber dimensions.