2.3. Asbestos-related lung diseases

Occupational or other environmental exposure to asbestos fibres may lead to hyaline plaques of parietal pleura, asbestos pleurisy, and asbestosis. Asbestos-induced malignancies of the respiratory tract include bronchogenic carcinoma and mesothelioma of the pleura. (Schwartz & Peterson 1998). Asbestosis leads to slowly progressive pulmonary fibrosis with a poor prognosis and a latency of 15-20 years from the first exposure to asbestos (Becklake 1976). The duration and intensity of asbestos exposure correlate to the quantity of fibres remaining in lung tissue and the quantity of asbestos bodies (AB) in bronchoalveolar lavage fluid (Davis 1994). There is a clear dose-response relationship between the severity of exposure of asbestos and the development of asbestosis. Pleural plaques and diffuse pleural thickening are also dependent on the cumulative dose of inhaled asbestos. 20-60% of construction workers exposed to high concentrations of asbestos develop signs of pleural fibrosis in chest radiographs. (Koskinen et al. 1998, Schwarz & Peterson 1998). It is unclear which individuals in an asbestos-exposed population are at risk of progressive pulmonary fibrosis. The chest radiographic finding is abnormal in a minority of the cases of pathologically demonstrated asbestosis (Kipen et al. 1987), and HRCT of the lungs is recommended for a diagnosis of asbestosis, especially in the early stages (Lynch 1998).