[Longitudinal study of radiologic anomalies in subjects working in asbestos-insulated buildings]

The respiratory effects of environmental pollution by asbestos was examined in a cohort of subjects working inside university buildings partly insulated with asbestos containing materials (University of Jussieu in Paris). The present study concerned 727 subjects having undergone two standard radiographic examinations (postero-anterior and oblique chest x-ray) in the period 1981-1992. The first examination was realized between 01/01/81 and 31/12/85 and the second examination took place between 01/01/86 and 31/12/92. The subjects were classified into three groups according to their exposure status: the group G1 consisted of 161 workers occupationally exposed to asbestos; the group G2 comprised 416 subjects working for at least 15 yr in asbestos-insulated buildings without known occupational exposure to asbestos; the group G3 consisted of 150 workers working for at least 15 yr in the university with no known exposure to asbestos. Whatever the radiological abnormalities considered, no significant difference was observed between G2 and G3 in cross-sectional analyses of the two phases. The group G1 exhibited a significantly higher prevalence of pleural thickening compared to the other exposure groups after adjustment for confounding variables. Detailed examination of oblique x-ray allowed to confirm that pleural thickening were largely due to extrapleural fat. Concerning the changes in pleural abnormalities between the two phases of the study, no difference was observed between G2 and G3. This study was unable to show any excess of radiographic chest abnormalities among subjects working in asbestos-insulated buildings compared to non-exposed subjects. However, the participation in the second phase of examination was 51.2%. The study is still on-going. Therefore, it would be necessary to continue to follow-up the subjects because respiratory disorders could occur after a long latent period.