Computed tomography findings in urban transportation workers with low cumulative asbestos exposure

To assess the frequency of computed tomography (CT) scan pleural and interstitial changes in a population of urban transportation workers with low cumulative exposure to asbestos, and to measure inter-reader agreement.

A total of 269 male volunteers (mean age 54.0 +/- 2.3 years, mean estimated cumulative exposure index 1.7 +/- 2.3 fibres/ml-years), underwent a CT scan which was read independently by three experienced readers, with further consensus reading in case of pleural or parenchymal abnormalities. Inter-reader agreement was assessed by means of Kappa statistic.

On consensus reading, four subjects had interstitial opacities, three had diffuse pleural thickening and 26 (9.7%) had pleural plaques that were unilateral in 65% of cases and < or =2 mm thick in 54% of cases. No correlation was observed between pleural plaques and latency, duration of exposure or cumulative exposure. The inter-reader agreement for the detection of pleural abnormalities was fair.

In this relatively young population with low cumulative exposure to asbestos, the prevalence of pleural abnormalities was low. These abnormalities were very limited in thickness and extent, leading to marked inter-reader variability and making it difficult to assess their relationship to asbestos exposure.