Pleural plaques, asbestos exposure, and asbestos bodies in bronchoalveolar lavage fluid

The profiles of occupational asbestos exposure were investigated in a series of 66 hospital patients in whom pleural plaques constituted the only asbestos-induced abnormality. The relationship between a radiological semiquantitative score of pleural plaques and indices of asbestos exposure was also examined. On the basis of a standardized occupational questionnaire, four classes of asbestos exposure were distinguished in our study population: no evidence of exposure, low-level exposure, sporadic exposure at higher levels, and a remaining group of individuals with substantial exposure. Asbestos body count in bronchoalveolar lavage fluid (BALF) was used as an objective indicator of cumulative lung retention of asbestos. Our results support the data indicating that pleural plaques may occur in subjects with low-level or sporadic asbestos exposure. Although it is admitted that pleural plaques are strongly associated with past asbestos exposure, our data suggest that the stage of pleural plaques was not correlated to the level, frequency, duration of exposure nor to the amount of asbestos bodies in the BALF in subjects free of any lung parenchymal abnormalities on high resolution computerized tomography.