Occupational pleural disorders almost exclusively concern those who have had exposure to asbestos fibres (and perhaps also refractory ceramic fibres).
Nonmalignant pleural disorders, such as localised pleural plaques, are a relatively frequent occurrence, even in those who have had light exposure to asbestos. Pleural plaques are considered as biomarkers of past exposure to asbestos. It is generally accepted that the mere presence of asbestos- induced pleural plaques does not usually lead to symptoms or impairment and that such plaques are not precursors of a malignant evolution. In contrast, pleurisy and diffuse pleural thickening are more serious manifestations of pleural disease that may result from relatively high cumulative exposure to asbestos. All of these nonmalignant pleural disorders may be seen in isolation or they may accompany asbestosis or malignant asbestos-induced disease.
Malignant mesothelioma is a pleural (or pericardial or peritoneal) tumour which is typically caused by asbestos exposure, either occupationally or environmentally. The majority of mesothelioma cases (>90%) are asbestos related and occupational exposure is the major contributor to its occurrence, though environmental sources have been identified in some countries. The latency period between exposure and the clinical manifestation of mesothelioma is usually ≥ 30 years, and the tumour may occur even after brief or low exposure. It has been predicted that the increase in the occurrence of malignant mesothelioma, which has paralleled the industrial use of the material, will continue until approximately 2020 in most European countries, killing about 250 000 people between 1995 and 2029. According to this prediction, one in 150 men born between 1945 and 1950 will die of this ‘rare’ tumour, for which no effective cure is presently available.
Mesothelioma mortality rates vary considerably between countries and it has been shown that these rates correlate strongly with the amount of asbestos imported into a country (figure 2). In Europe, mortality rates vary more than 10-fold between countries (figure 3), and it is likely that this variation reflects the differences in asbestos use post-second world war, although the low rates seen in some countries might also be associated with diagnostic issues.