[Risk assessment of benign asbestosis (dose-effect relationship, time-effect relationship, co-factors)]

Despite the lack of precision of asbestos exposure assessments and the limitations of the main diagnostic epidemiological tool for asbestos-related diseases (i.e. standard X ray films), several issues concerning the risk of development of asbestos-related diseases are well established. For asbestosis, now a rare disease, the existence of a positive dose-response relationship, with a threshold or no-effect level, has been clearly demonstrated. The slope of the relationship curve is steeper for amphiboles than for chysotile, as it is for increased fiber length. Asbestosis is associated with an increased risk of bronchial carcinoma, however it is now known that exposure to asbestos of itself increases the risk of cancer even in the absence of any radiographic signs of pulmonary fibrosis. Pleural plaques occur even when the level of asbestos exposure is low. They are not only dose-dependent but are also latency-related. They have no prognostic significance in asbestos-exposed workers, but are associated with an increased risk for the subsequent development of mesothelioma and bronchial carcinoma when compared to the risk of the general population. Diffuse pleural thickening is associated with higher levels of asbestos exposure than those associated with pleural plaques. It usually follows a benign pleural effusion, which is a less frequent but earlier consequence of asbestos exposure than the other asbestos-related diseases documented above.