Graduation Date

Fall 12-16-2016

Document Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Dr. Tricia LeVan


Agricultural workers are at risk for respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and chronic bronchitis, due to exposures and inflammatory agents found in their work environment. While previous studies have been conducted to examine agricultural effects of chronic respiratory diseases more closely, there are still several significant gaps in the existing literature.

This dissertation explores the relationship between agricultural exposures and respiratory diseases. Utilizing two populations, the Keokuk Country Rural Health Study and the AgLung Study, this research: 1) used principal factor analysis (PFA) to distill exposure data into essential variables characterizing long-term agricultural exposures in order to examine the relationship between agricultural exposures and chronic respiratory diseases, 2) examined the relationship between TLR4 299/399 polymorphisms with chronic bronchitis and pro-inflammatory cytokines in two agriculturally-exposed populations, and 3) examined the lung microbiome longitudinally in agriculturally-exposed individuals with stable COPD. The results of the studies included in this dissertation may assist in continuing to fill the gaps in knowledge in this area of study in order to improve respiratory health in agricultural workers.