Excess of Mesotheliomas after Exposure to Chrysotile in Balangero, Italy

Occupational and Environmental Medicine. 2008 Jun 4. [Epub ahead of print] [Link]

Mirabelli D, Calisti R, Barone Adesi F, Fornero E, Merletti F, Magnani C.

Unit of Cancer Epidemiology, CeRMS and CPO-Piemonte, University of Turin, Italy.


Context: Chrysotile from the mine in Balangero, Italy, is considered to be tremolite-free. In a cohort study of miners and millers only two pleural cancers were reported, a finding considered to contribute evidence that chrysotile has a low potency for inducing mesothelioma. However, follow-up ended in 1987 and white-collar workers and employees of sub-contractors were not studied.

Population and Methods: To complete the case ascertainment, we searched the Registry of Malignant Mesotheliomas of Piedmont for records of cases among: mine employees; employees of subcontractors or of other firms transporting or refining Balangero asbestos, asbestos ore or mine tailings; individuals exposed to air pollution from the mine or living with mine employees; and individuals exposed to mine tailings from Balangero.

Results: We identified 4 new cases of pleural mesothelioma among blue-collar workers in the mine, in addition to the two reported in the cohort study. Thus, 6 mesotheliomas occurred, compared to 1.5 expected (p <0.01). We also identified 3 mesothelioma cases among white-collar employees at the mine, 5 in workers in the mine hired by subcontracting firms, and 3 among workers processing Balangero chrysotile outside the mine. Finally, 10 additional cases were identified due to non-occupational exposure or exposure to re-used mine tailings.

Conclusions: The cluster of 14 mesothelioma cases among workers who were active in the mine and 13 among other people exposed to Balangero chrysotile adds further evidence to the carcinogenicity of tremolite-free chrysotile.