Indicators of asbestos exposure in autopsy routine. 2. Pleural plaques and occupation

The significance of pleural plaques as indicators of occupational exposure to asbestos was studied in 898 adult subjects examined at post-mortem in Torino (Italy) from September 1977 to June 1981. Pleural plaques were subdivided in three grades according to the total extension, and the subjects were allocated into four categories as to occupational exposure: definite, probable, possible and absent. The presence, as well as the grade of extension of the pleural plaques were significantly related to occupational exposure to asbestos; furthermore, a relationship between the length of the period elapsed from initial exposure to death, as well as between the duration of exposure and presence of such pleural changes, was recorded. Nevertheless, in individual cases, pleural plaques may be absent even in subjects with definite and long occupational exposure, while severe lesions can be observed in non exposed people. Therefore, plaque lesions of the pleura may be a useful indicator of exposure to asbestos in population studies, however their validity in individual cases observed in pathological routine is more limited.