Lung and other cancer site mortality in a cohort of Italian cotton mill workers

Abstract

Background Several studies report a lower than expected mortality in lung cancer among workers exposed to organic dust. A recent study also reported a decreased risk for cancer at other sites.Objectives. To evaluate the mortality from lung and other cancer sites in cotton mill workers.

Material and methods A cohort of 3961 Italian cotton mill workers was divided in those working with carding (exposed to high levels of endotoxin-containing cotton dust) and other tasks, which generally have lower exposure. Standardized mortality ratios (SMR), with 95% confidence intervals (CI), were calculated using death rates of the regional general population as a reference. Cancer mortality was analyzed in relation to the length of employment in the two task groups. An internal analysis was also performed through Poisson regression.

Results Among workers in carding departments, lung cancer SMRs were 1.88 (CI=0.69-4.08), 1.01 (0.20-2.94), and 0.22 (0.00-1.24) respectively for <6, 6-12, and >12 years of employment (chi square for trend=5.45; p<0.05). A significant (p=0.04) trend was confirmed by Poisson regression. No reduced risks were found for other forms of cancer, nor for those working with other tasks.

Comments The results support previous reports that a high and prolonged exposure to cotton dust and other endotoxin containing organic dusts is related to a lower the risk of lung cancer. There was no indication of a reduced risk for other forms of cancer.