Radiological evaluation of early pleural and pulmonary changes in light asbestos exposure.

In a case-control study of 209 workers from a local railway maintenance and repair workshop, pleuropulmonary lesions were studied on chest radiographs. All workers were known to have been exposed to asbestos fibers of all kinds for a long period of time, but the exposure was light. A "dose index" of every worker was calculated based upon the type of working process and cumulated time spent in the working process. We found a certain dose-effect relationship between asbestos exposure and pleural thickening.