Cancer incidence among male pulp and paper workers in Norway

Objectives The study investigated cancer incidence among 23718 male pulp and paper workers employed continuously for at least 1 year between 1920 and 1993 in Norway. Methods The name, date of birth, personal identification number, dates of hire and termination for all employment periods, specific department, and job categories were registered for each worker. Six subcohorts were established (sulfite mill, sulfate mill, paper mill, maintenance department, administrative staff and other departments). Data on the cohort were linked with data in the Norwegian Cancer Register. The follow-up period for cancer incidence, date of death, or emigration was from 1953 through 1993. Results An excess incidence of lung cancer was found among both short- and long-term employees [standardized incidence ratio (SIR) 1.5, 95% confidence interval (95% CI) 1.13-2.03 and SIR 1.2, 95% CI 1.09-1.34, respectively], especially for workers with the longest latency (SIR 1.3, 95% CI 1.08-1.44) and for sulfite mill workers (SIR 1.5, 95% CI 1.09-1.99). The risk for pleural mesothelioma was also increased (SIR 2.4, 95% CI 1.45-3.75), especially among maintenance workers. The results also showed an increased risk for malignant melanoma(SIR 1.3, 95% CI 1.04-1.60), an unexpected finding. Conclusions Almost all the increased risk for lung cancer can be explained by a combination of smoking habits and asbestos use, although an effect of other work-related exposures (sulfur and chloride compounds, wood dust) cannot be excluded. Most of the cases of pleural mesothelioma occurred in departments where asbestos was used. Then is no clear explanation for the excess of malignant melanoma, and the finding may be a chance occurrence.