Detection and analysis of endogenous polar volatile organic compounds (PVOCs) in urine for human exposome research

Abstract

Background: The human exposome, defined as ‘…everything that is not the genome’, comprises all chemicals in the body interacting with life processes. The exposome drives genes x environment (GxE) interactions that can cause long-term latency and chronic diseases. The exposome constantly changes in response to external exposures and internal metabolism. Different types of compounds are found in different biological media.

Objective: Measure polar volatile organic compounds (PVOCs) excreted in urine to document endogenous metabolites and exogenous compounds from environmental exposures.

Methods: Use headspace collection and sorbent tube thermal desorption coupled with bench-top gas chromatography-mass spectrometry (GC-MS) for targeted and non-targeted approaches. Identify and categorize PVOCs that may distinguish among healthy and affected individuals.

Results: Method is successfully demonstrated to tabulate a series of 28 PVOCs detected in human urine across 120 samples from 28 human subjects. Median concentrations range from below detect to 165 ng/mL. Certain PVOCs have potential health implications.

Conclusions: Headspace collection with sorbent tubes is an effective method for documenting PVOCs in urine that are otherwise difficult to measure. This methodology can provide probative information regarding biochemical processes and adverse outcome pathways (AOPs) for toxicity testing.

Keywords:

• Biomarkers
• urinary metabolites
• gas chromatography/mass spectroscopy
• human exposome
• adverse outcome pathways
• non-targeted analysis

Acknowledgments

The authors are grateful to Adam Biales, Andrew Lindstrom, Karen Oliver, and Michael Madden of US EPA, and William Funk of Northwestern University School of Medicine for expert advice. We are also grateful to Marsha Morgan of US EPA for organizing the original Ex-R study. This work was reviewed according to US EPA protocols and approved for publication. Reference to manufacturers and trade names are not recommendations for use.

Disclosure statement

No potential conflict of interest was reported by the authors.