[Epidemics of lung tumors in a Biella tannery].
A cluster of 7 lung cancer deaths among workers of a small tannery in Biella is reported. The major process in the plant, until the end of World War II, was chromium and vegetable tanning. A historical cohort study was carried out on a total of 353 male workers. The expected number of death was estimated on the basis of local mortality rates. An SMR for lung cancer of 449 (95% C.L. 180-925) was found for the entire cohort. Excluding workers non specifically employed in tanning operations, the SMR for lung cancer increased to 1087 (95% C.L. 352-2533). In order to control for potential confounders a nested case-control study was planned. The next-of-kin of 8 cases deceased for lung cancer and 32 controls matched by age were interviewed on smoking habits and previous jobs. Logistic regression analysis showed an O.R. of 6.94 (95% C.L. 1.18-40.73), adjusted for smoking habits and occupational history, for subjects involved in tanning operations. A registry of incident cases of cancer was established in order to avoid biased findings based on cluster cases.