Mortality from cancer and other causes among workers at a metal refinery.

Hidden cases of occupational lung cancer among males were revealed by a case-control study in a town. The findings were confirmed by a prospective study on mortality among the employees of a metal refinery. It demonstrated not only a significantly increased mortality from lung cancer among copper smelters but also definite dose-response relationships between mortality from lung cancer and the degree of exposure. A very high excess mortality from lung cancer (0/E = 25.00) was observed among copper smelters who were considered to have been most heavily exposed to arsenic and/or other carcinogenic substances or workers who had been engaged in sintering and blast furnace operations for 15 years or more before 1949. The average latency period of lung cancer was 37.6 years, and unrelated to the level of exposure. Twenty-six of 29 deaths from lung cancer among copper smelters occurred after they had left the company. Other production workers and clerical workers showed no significant excess mortality from any kind of cancer.