[Malignant mesothelioma and asbestos]

Malignant mesothelioma is a rare neoplasm of rapidly lethal course arising primarily in the pleura and less often in the peritoneum. In the majority of cases the disease is closely related to occupational exposure to asbestos. The latency period, calculated from the first contact with asbestos to the appearance of mesothelioma, is generally in the order of 20 years or more irrespective of the duration of exposure. A causal relationship can be established with certainty only by a careful history and positive tissue analysis for the presence of asbestos. The author's own series of 48 pleural mesotheliomas comprises 39 cases involving occupational exposure to asbestos, 6 others with asbestos demonstrable in pulmonary tissue but no discernible source in the history, and 3 where no relation to asbestos could be established at all. Although a dose-response relation may be assumed for asbestos as for all other carcinogens, the lack of data on asbestos dust concentrations at former places of work rendered determination of the minimal noxious dose difficult or impossible. It also remains unclear whether the various asbestos types, such as chrysotile and amphiboles, differ in pathogenic effect. It is hoped that careful registration and continuing study of mesotheliomas will shed further light on their relationship to asbestos and on the possible hazards of the mineral to the general population.