Lung cancer mortality in a cohort of older pulp and paper workers

Abstract

The occurrence of deaths due to lung cancer was studied among 883 white male workers from a pulp and paper company in northern New Hampshire. All subjects had participated in a longitudinal study of respiratory morbidity, and data from interviews were used to construct lifetime cigarette smoking and occupational histories. Most of the subjects had entered follow-up in the 1960s and, at that time, their mean age was 51 years and they had worked for the pulp and paper company a mean of 25 years. By the end of follow-up in 1992, the 512 deceased subjects included 35 whose underlying cause of death had been lung cancer. With an internal comparison using the Cox proportional-hazards model, the hazard ratio for sulfite pulp mill work was 2.5 (95% CI 1.3-4.9), while controlling for the effects of age, cigarette smoking, and work in other parts of the pulping operation. In addition, the hazard ratio for the combination of >35 pack-years of smoking and >10 years sulfite mill work was greater than the product of the hazard ratios for each factor alone. While these findings are consistent with past asbestos exposure in the sulfite pulp mill environment, the absence of mesothelioma cases is inconsistent with this type of exposure.