The incidence of malignant mesothelioma (1977-1996) and asbestos exposure in the population of an area neighboring Lake Iseo, northern Italy

The study was stimulated by the occurrence of malignant mesotheliomas among the workers of two adjacent factories located in Sarnico, near Lake Iseo (province of Brescia, northern Italy), one of which manufactured crocidolite and chrysotile ropes and gaskets until 1993. The aim of the study was: identification of malignant mesotheliomas occurring between 1977 and 1996 among the residents of 11 villages, which constituted the recruitment area of the work-force; estimation of the incidence of malignant pleural mesothelioma; collection of working histories of all cases to evaluate previous exposure to asbestos and radiation therapy. 21 cases of mesothelioma were detected (20 pleural, 1 peritoneal; 9 among males), and 20 were supported by histopathologic diagnosis. The incidence (x 100,000 person-years, standard: European population) was 2.5 (0.7-4.2) and 2.8 (1.2-4.3) among males and females, respectively, corresponding to a three-fold increase among males and a more than ten fold increase among women in comparison with the incidence reported by the Lombardy Cancer Registry. No cases had been exposed to radiation therapy, whereas all cases had been occupationally exposed to asbestos. Occupational exposure to asbestos had occurred in work on the production of crocidolite and chrysotile ropes and gaskets (6 males); in work in a textile factory producing cotton garments that was adjacent to and polluted by the former, where, in addition, chrysotile blankets were used for fireproofing in the weaving area and pipes were insulated using amosite-containing materials (10 cases, 6 among females); 5 cases occurred among women working in silk factories, where asbestos exposure was possible because of the presence of pipes insulated with asbestos and because women were handling temperature-controlled trays insulted with asbestos. In conclusion, the study demonstrated that the occurrence of mesothelioma was higher among females than males in the study area and that all cases of mesotheliomas had been occupationally exposed to asbestos.