Surface of localized pleural plaques quantitated by computed tomography scanning: no relation with cumulative asbestos exposure and no effect on lung function.

To evaluate if there is a relation between the size of asbestos plaques and the level of past exposure and pulmonary function, we measured the surface of localized pleural plaques found on high-resolution (HR) CT scan, using a computerized video display unit-imaging system, in 73 workers (mean age, 43.5 yr) who had worked from 23 to 27 yr in an asbestos-cement factory. Their estimated cumulative exposure to asbestos ranged from 16.4 to 98.7 fiber-years/ ml (mean, 26.3 fiber-years/ml). Lung function measurements included lung volumes, maximal expiratory flows, and diffusing capacity. A control group of 21 workers was examined by the same procedures. Plaques were detected by CT in 51 (70%) asbestos-exposed subjects and in none of the control subjects. The average calculated plaque surface was 47.9 +/- 61.7 cm2 (median, 22.1 cm2; range, 0 to 278.4 cm2). There was no relation between plaque surface and cumulative asbestos exposure (p = 0.24). In the 51 subjects with pleural plaques, the surface of the pleural lesions was not related to cumulative asbestos exposure, or to smoking history or time since first exposure. Neither the presence nor the extent of the plaques was correlated with lung function parameters.