A cohort study on mortality from cancer and other causes among workers at a metal refinery

A non-concurrent prospective study was made on deaths from cancer and other causes occurring among 2,675 male workers at a metal refinery from 1949 to 1971. The expected number of deaths computed by applying age- and cause-specific death rates of Japanese males to these workers was compared with the observed number of deaths. Among 839 copper smelters, significantly increased mortalities were noted for lung cancer (SMR = 1,189) and colon cancer, but nor for cancer of the stomach, liver (primary) and biliary passages, pancreas and skin or for leukemia, tuberculosis, cerebrovascular diseases, heart diseases and liver cirrhosis. A dose-response relationship was demonstrated between the mortality from lung cancer and the degree of exposure. A very high excess mortality from lung cancer (SMR = 2,500) was seen among copper smelters who were considered to have been most heavily exposed to arsenic or workers who had engaged in sintering and blast furnace operations for 15 years of more before 1949. The latent period of lung cancer was 37.6 years on average, and not related to level of exposure. Twenty-six of 29 deaths from lung cancer among copper smelters occurred after they had left the refinery. Other production workers and clerical workers showed no significant excess mortality from any kind of cancer.