Since 1980, we have collected fourteen cases of mesothelioma induced by environmental exposure to asbestos, going back to childhood in patients from north-east Corsica, in a region which was remote from the asbestos mine of Canari. There were eight men and six women with a mean age of 69.5 +/- 4 years. Six patients presented with bilateral calcified pleural plaques as evidence of environmental exposure. The mineral analysis carried out on five patients (four had thoracoscopies and one an alveolar lavage), showed a moderate deposit of chrysotile (0.3 to 3.4 x 10(6) fibres per gram of dry tissue), and elevated level of tremolite (1.4 to 62 x 10(6) fibres/g). The ambient dosage of asbestos has confirmed the existence of environmental pollution by chrysotile fibres and above all by tremolite. In addition, the same type of fibres have been identified in the parietal pleural of animals subjected to the same risk. In this region, the risk is estimated, on the basis of our results, as 10 cases of mesothelioma per 100,000 inhabitants per year.