پلاك پرده جنب تظاهر ريوي اوليه در تماس با آزبست مطالعه اي بر كارگران معدن و كارخانه آزبست كرويزوتايل حاجات 0- نهبندان

PLEURAL PLAQUE AS AN ESSENTIAL PULMONARY INVOLVEMENT DUE TO ASBESTOS EXPOSURE, A STUDY ON HAJAT- NEHBANDAN CHRYSOTILE MINE & FACTORY WORKERS

Background & Aims: Asbestos with top physiochemical specialities has widely used in industries. But actually dangerous effects in many human organs, especially respiratory system, results in its restriction and serious intention. Benign pleural plaque and malignant mesothelioma are the main and serious effects of asbestos. Itʹs said that these effects (especially malignant mesothelioma) is rare by kind of chrysotile asbestos. Detection of pleural involvement is difficult in C.X.ray, done routinely in occupational periodic examination. This investigation is about a clinical finding in asbestos pleural involvement and HRCT vs. C.X.ray, as a suitable diagnostic device for evaluation of the pleural involvement due to Asbestos pulmonary changes. Materials & Methods: A total of 56 asbestos mine workers were randomly chosen. The level of asbestos in the different areas of the factory and mine was measured. All of the workers were interviewed and underwent clinical examination, C.X.ray & HRCT. HRCT was interpreted by 3 radiologists, first separately, then in consultation. Results: The mean value of asbestos in the respiratory field of asbestos exposed workers was about 80 times over standard limit (39.75 f/ml; TLV= 0.5 f/ml). HRCT finding demonstrates parenchymal involvement in 39 individuals (69.63%) & pleural involvement in form of pleural plaque or pleural thickening in 30 individuals (53.55%). But, according to ILO classification, C.X.ray shows parenchymal involvement in 6 individuals (10.9%) without any pleural involvement. There is a significant difference between HRCT& C.X.Ray in detection of the pulmonary changes (both parenchymal and pleural involvement) (p<0.01). Discussion: The results demonstrate no significant correlation between increases of pleural involvement and rise of Asbestos fibers in workers, respiratory field. But there is notification that, pleural plaque may be occurred without any respiratory sign & symptom. Also, this study demonstrates that, in evaluation of Asbestos pulmonary changes (especially pleural involvement), C.X.ray isnʹt valuable, but HRCT can plays an important role; especially when there is pleural lesions without parenchymal involvement.