Previous studies have linked endotoxin exposure with increased risk of COPD, but a decreased risk for lung cancer. We examined these associations in a cohort of British Columbia (BC) sawmill workers followed between 1950 and 1995.Methods
The cohort comprised all male production and maintenance workers (n=25,685) at 14 BC sawmills employed for at least one year between 1950 and 1995. Lung cancer cases were identified through the provincial cancer registry, and COPD cases through the provincial hospital discharge data. We assigned cumulative endotoxin exposure for each subject based using a job-exposure matrix built on measurement data obtained at 4 of the study mills. Subjects were assigned to exposure quintile groups for analysis (groups between <1.5 ng/m3 and >14.7 ng/m3), and adjusted risk estimates for each group were calculated using Poisson regression, controlling for potential confounders (smoking that was indirectly addressed).Results
Relative risk of lung cancer for highest exposed group was 0.73 (95% CI 0.55–0.98) compared to the reference group, with a slight trend of decreasing risk with increasing endotoxin exposure. Relative risk for COPD in the highest exposed group was 1.9 (95% CI of 0.95–3.70) compared to the reference group, with a slightly increasing trend with increasing endotoxin exposure. Results did not change when different lag times were examined.Conclusion
Our findings of a protective effect for endotoxin exposure and lung cancer, and a positive association between endotoxin and COPD are consistent with previous studies, but at lower exposure levels.