Conflicting Effects of Occupational Endotoxin Exposure on Lung Health - A Hypothesis- Generating Review of Cancer and COPD Risk

128 Journal of Environmental Immunology and Toxicology Volume 1 Issue 3 Abstract Occupational exposure to endotoxin has been previously associated with increased risk of chronic obstructive pulmonary disease (COPD) and other chronic lung conditions. However, occupational endotoxin exposure has been shown to be associated with a decreased risk of several cancers, including lung cancer. The purpose of this review is to assess the current literature on endotoxin, COPD and lung cancer and generate directions for future research assessing the mechanisms of these contradictory effects of endotoxin on lung health. A systematic literature search was conducted to locate relevant papers in English, published up to June 2012, using Medline and NIOSH-TIC2. Based on the current literature, the mechanisms of endotoxin-related COPD causation and lung cancer protection appear to operate through differential effects of an inflammatory response to inhaled endotoxin. In particular, COPD risk and cancer prevention appear to both be driven by activation of cytokines, including TNF-α and IL-12, through inhaled endotoxin. In addition, genetic polymorphisms and both duration and level of exposure may be important determinants of disease. We recommend that further research on the role of endotoxin and lung disease focus on understanding the effects of the duration or level of exposure to endotoxin necessary for development of COPD, and on determining the stage of tumor development most affected by endotoxins.