Journal Article

Lung Cancer Risk: Effect of Dairy Farming and the Consequence of Removing that Occupational Exposure

Giuseppe Mastrangelo, John M. Grange, Emanuela Fadda, Ugo Fedeli, Alessandra Buja and John H. Lange

in American Journal of Epidemiology

Published on behalf of Johns Hopkins Bloomberg School of Public Health

Volume 161, issue 11, pages 1037-1046
Published in print June 2005 | ISSN: 0002-9262
Published online June 2005 | e-ISSN: 1476-6256 | DOI: http://dx.doi.org/10.1093/aje/kwi138
Lung Cancer Risk: Effect of Dairy Farming and the Consequence of Removing that Occupational Exposure

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The aim of this study was to confirm the exposure-dependent reduction in lung cancer risk reported for dairy farmers exposed to endotoxin and to evaluate the consequence of leaving dairy farming and taking employment in industry or services, where exposure to microbial agents is lower. Standardized mortality ratios, with 95% confidence intervals, for 2,561 self-employed dairy farmers were estimated, considering the general population of Veneto, Italy, from 1970 to 1998 as the reference. Sixty-two lung cancer cases, whose information was checked against clinical records, were compared with 333 controls in a cohort-nested case-control study. Odds ratios with 95% confidence intervals were estimated by logistic regression analysis. A downward trend of standardized mortality ratios for lung cancer across tertiles of number of dairy cattle on the farm was significant (p < 0.05) from 1970 to 1984 but not from 1985 to 1998, when most subjects were no longer dairy farmers. Age- and smoking-adjusted odds ratios for lung cancer significantly decreased with increasing number of dairy cattle (p for trend = 0.001) for workers for whom ≤15 but not >15 years had elapsed from the end of work to the end of follow-up. In conclusion, increased levels of endotoxin (or other associated environmental factors) might be protective against lung cancer; protection diminishes over time after that exposure is removed.

Keywords: case-control studies; cohort studies; dairying; endotoxins; lung neoplasms; tumor necrosis factor-alpha; CI, confidence interval; Th, T helper cell; TLR, toll-like receptor

Journal Article.  6508 words. 

Subjects: Public Health and Epidemiology

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