Date on Master's Thesis/Doctoral Dissertation

5-2020

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Epidemiology and Population Health

Degree Program

Public Health Sciences with a specialization in Epidemiology, PhD

Committee Chair

Zierold, Kristina

Committee Co-Chair (if applicable)

Taylor, Kira

Committee Member

Groenewold, Matthew

Committee Member

Bhatnagar, Aruni

Committee Member

Rai, Shesh

Committee Member

Boone, Stephanie

Author's Keywords

Volatile organic compounds; VOCs; urinary biomarkers of exposure; cardiometabolic syndrome; nationally-representative; national health and nutrition examination survey (NHANES)

Abstract

BACKGROUND: The relative importance of environmental exposures such as volatile organic compounds (VOCs) is one of the paramount public health priorities of our time, yet is presently unstudied. VOCs are ubiquitous in the environment and have been associated with numerous adverse health effects, including a number of cardiovascular and metabolic effects that are components of Cardiometabolic Syndrome (CMS). OBJECTIVES: To examine the relationship between CMS and individual-level exposures to VOCs, measured as urinary metabolites of VOCs (UM-VOCs), in a nationally representative sample. METHODS: Associations between urinary biomarkers of exposure to 19 parent VOCs and CMS were assessed using the National Health and Nutrition Examination Survey (NHANES). To isolate effects from environmental VOC exposures, analyses were stratified by tobacco-smoke exposure status. CMS was treated dichotomously as well as ordinally and associations with VOCs were considered from a single pollutant, as well as multi-pollutant perspectives. Potential important groupings and interactions among VOCs, and their associations with CMS were evaluated using numerous traditional regression modeling and exploratory modeling methods including: backwards-selection model-building, factor analysis, LASSO penalized regression, and a cumulative VOC exposure score. RESULTS: Concentrations of eight UM-VOCs were significantly different between individuals with and without CMS. Among the non-smoke exposed participants, 6 UM-VOCs were significantly associated with increased odds of CMS. These associations were observed with metabolites from acrolein, 1,3-butadiene, crotonaldehyde, cyanide, and ethylbenzene/styrene. Furthermore, dose-response type relationships were observed with metabolites of acrolein, 1,3-butadiene, and crotonaldehyde. Metabolites from acrolein and ethylbenzene/styrene were associated with disease progression in ordinal logistic regression models and a cumulative VOC exposure score was significantly associated with the progression of disease towards clinically diagnosable CMS (OR: 1.015, 95% CI: 1.007, 1.024). DISCUSSION: This novel quantitative and nationally representative study investigated associations between individual-level exposures to VOCs and CMS. The results of this study point toward a potential causal role for certain VOCs in the development of CMS, a condition which ultimately greatly increases one’s risk of the deadliest non-communicable disease in the world, cardiovascular disease. These findings are important for the development of public health interventions and policies surrounding modifiable environmental pollution exposures.

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