Scanning Microscopy


Because of the relatively small data base existing for lung particulate burdens of subjects with no overt pneumoconioses, the total exogenous lung particulate concentrations of 91 subjects from the Cincinnati, Ohio urban area were determined using an automated scanning electron microscope-energy dispersive x-ray analysis-image analysis system. Four of these subjects were foundry workers and had the highest exogenous particle concentrations seen in the 91 lungs, ranging from 1860 to 2990 x 106 particles per gram of dry lung (ppg). The average exogenous particle concentration for the remaining 87 subjects was 476 ± 380 x 106 ppg with a range of 71 to 1860 x 106 ppg. The median size of the exogenous particles in the 87 lungs was narrow, ranging from 0.37 to 1.02 µm. The geometric mean particle size over all 87 lungs was 0.60 µm with a geometric standard deviation (σg) of 2.35. The total exogenous particle levels were elevated for the male subjects compared to females (p=0.015), and were positively associated with age (p=0. 021). However, no correlation was seen between total particle concentration and race or smoking history.

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