Combined effects of underground mining (nonuranium mines) and smoking were analyzed in a case-control study of male lung cancer in northern Sweden. Lung cancer cases exposed to underground mining had a considerably lower average cumulative tobacco consumption than other lung cancer cases, indicating that smoking is especially dangerous for underground miners. When relative risks were estimated, a synergistic effect of multiplicative type was found between smoking and underground mining.
Of 199 persons employed in the manufacture and handling of Canadian military gas mask canisters containing pure crocidolite, 1939 to 1942, by the end of 1975, 56 had died, 120 were still alive, and 23 could not be traced. Nine (16%) of the deaths were probably due to malignant mesothelioma, six involving the peritoneum. The risk of mesothelioma after crocidolite exposure appears to be many times greater than that after chrysotile.