Publication Date

2008-07-31

Availability

Open access

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Epidemiology (Medicine)

Date of Defense

2008-07-25

First Committee Member

Lora E. Fleming - Committee Chair

Second Committee Member

Kristopher L. Arheart - Committee Member

Third Committee Member

David J. Lee - Committee Member

Fourth Committee Member

James D. Wilkinson - Committee Member

Fifth Committee Member

Berrin Serdar - Outside Committee Member

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are environmental and occupational carcinogens that are produced by the incomplete combustion of organic material, such as from the burning of tobacco, coal, and petroleum products. In addition to causing cancer, exposure to PAHs is hypothesized to contribute to atherosclerosis and to lead to increased incidence rates of cardiovascular disease in populations. Considering the number of deaths attributable to tobacco smoke exposure, ambient air pollution, and occupational hazards, PAHs may be a significant contributor to the prevalence of cardiovascular disease in human populations. However, a clear exposure-response relationship between PAHs and measures of cardiovascular disease has not been demonstrated. While PAH exposure has been shown to be associated with indicators of cardiovascular disease in research animals, this relationship has not been studied comprehensively in human populations. Using data from the continuous National Health and Nutrition Examination Surveys (NHANES) 1999 - 2004 of a representative sample of the entire US civilian population, this study investigated predictors of total body burden of PAHs and associations between urinary metabolites of PAHs and biomarkers of cardiovascular disease in 4,492 study participants aged 20 years and older. Using various analytic approaches, this research project identified tobacco smoke exposure as a significant predictor of urinary levels of low molecular weight PAHs but not as a predictor of urinary levels of high molecular weight PAHs in a large population of individuals without known occupational exposure to PAHs. Worker occupational category was not associated with urinary levels of any PAH metabolites. The results of this study also indicate a possible association between exposure to PAHs and the development of cardiovascular disease in humans. Levels of multiple metabolites of specific PAHs, naphthalene, fluorene, and phenanthrene were significantly associated with increases in total cholesterol, triglycerides, WBC count, and C-reactive protein levels. Additionally, this study examined the utility of factor analysis for data reduction of 23 urinary PAH metabolites to two latent factors representing low and high molecular weight PAHs to streamline investigations of the associations of PAH exposures with various health outcomes. Results of this study suggest mechanisms by which PAH exposure contributes to the burden of cardiovascular disease on human populations and the methods by which human body burden on PAHs can be measured.

Keywords

Cardiovascular Disease; Polycyclic Aromatic Hydrocarbons; Occupation; Inflammatory Markers; Tobacco Smoke Exposure

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