ASBESTOS BODY FORMATION IN THE HUMAN LUNG - DISTINCTIONS, BY TYPE ANDSIZE

The fraction of fibers coated in a total of 3 800 asbestos fibers from 38 patients with disease related to asbestos (100 fibers per patient) was determined, according to asbestos fiber type and size parameters, Among the 3 800 fibers, 638 (16.8%) were coated and 3 162 were uncoat ed. All fibers were analyzed at 2 000x magnification (lower limit of d etection: 2 mu m for length and 0.06 mu m for diameter). The diameter of the totally coated fibers (28.4% of total bodies; 181/638) was not measured. The percentage of coated fibers varied with the asbestos typ e; it was 27.1% (335/1235) for amosite fibers, 16.0% (228/1423) for cr ocidolite, 6.6% (60/908) for tremolite or actinolite, 6.5% (14/214) fo r anthophyllite, and 5% (1/20) for chrysotile fibers. Most coated fibe rs were longer than 10 mu m and had an aspect ratio (length/diameter) of more than 20. Approximately 60% of coated fibers had an aspect rati o of more than 100. The longer the fiber, the greater the percentage o f coated fibers, regardless of diameter. The increase in the percentag e associated with length was more marked in fibers with a smaller diam eter; the percentage of coated fibers was, therefore, greater in fiber s 30 mu m or less in diameter. However, in fibers longer than 30 mu m, the relationship to percentage of coated fibers was not as clear, and the diameter was less important. Accordingly, the fibers with high as pect ratios, particularly long fibers, tended to show asbestos body fo rmation. The percentage of long fibers was highest in amosite, and the percentage of fibers with an aspect ratio of more than 100 was highes t in amosite and crocidolite. The percentage of coated fiber for these two fiber types was higher than for any other type.