Ethane and n-pentane in exhaled breath are biomarkers of exposure not effect

Abstract

The relationship of exhaled ethane and n-pentane to exhaled NO, carbonylated proteins, and indoor/outdoor atmospheric pollutants were examined in order to evaluate ethane and n-pentane as potential markers of airway inflammation and/or oxidative stress. Exhaled NO and carbonylated proteins were found to have no significant associations with either ethane (p = 0.96 and p = 0.81, respectively) or n-pentane (p = 0.44 and 0.28, respectively) when outliers were included. In the case where outliers were removed n-pentane was found to be inversely associated with carbonylated proteins. Exhaled hydrocarbons adjusted for indoor hydrocarbon concentrations were instead found to be positively associated with air pollutants (NO, NO₂ and CO), suggesting pollutant exposure is driving exhaled hydrocarbon concentrations. Given these findings, ethane and n-pentane do not appear to be markers of airway inflammation or oxidative stress.

Keywords::

• Ethane
• pentane
• nitric oxide
• carbonylated proteins
• oxidative stress
• exhaled breath analysis

Acknowledgements

We thank members of the Rowland-Blake research group from the Department of Chemistry, University of California Irvine, who assisted in the laboratory and with data analysis. We also thank staff from the Department of Epidemiology, University of California Irvine, the General Clinical Research Center (MO1 RR00827), University of California Irvine, the California Air Resources Board, and the South Coast Air Quality Management District, who assisted in the collection of data. MPSA acknowledges the Comer foundation for a research fellowship. The project described was supported by grant number ES012243 from the National Institute of Environmental Health Sciences, U.S. National Institutes of Health, the U.S. Environmental Protection Agency grant number RD83241301, and the California Air Resources Board contract number 03-329. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the funding agencies. The authors declare they have no competing financial interests.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.