Asbestos exposure, smoking habits, and cancer incidence among production and maintenance workers in an electrochemical plant.

The incidence of cancer was studied in a cohort of 287 men who were exposed to asbestos at a nitric acid production plant from 1928 onwards. During the observation period from 1953 through 1980 all cancer cases among the cohort members were identified in The Cancer Registry. For the whole cohort 42 cases of cancer were observed versus 30.6 expected. The figures for cancer of the lungs and pleura combined were 17 observed versus 3.7 expected. The corresponding figures for a heavily exposed subcohort were 11 observed and 1.2 expected. In that group there was also an increased incidence of colon cancer with 3 cases observed against 0.8 cases expected. Within the whole cohort four cases of pleural and one case of peritoneal malignant mesothelioma were found. There was also an increased incidence of malignant melanoma of the skin with 3 cases observed against 0.6 expected. For cancer cases that were registered as of unknown origin there were 7 cases observed and 1.4 expected. There was no increased rate ratio for cancer at any site before 20 years after the first asbestos exposure. The smoking habits of all cohort members were recorded and the relative rates for lung cancer were calculated in relation to smoking habits. In common with previous studies the results indicate a multiplicative model for the interaction between asbestos exposure and smoking in regard to lung cancer risk.