Citation:

Wallace, A., J. Pleil, K. Oliver, D. Whitaker, S. Mentese, K. Fent, AND G. Horn. Non-targeted GC/MS analysis of exhaled breath samples: Exploring human biomarkers of exogenous exposure and endogenous response from professional firefighting activity. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH - PART A: CURRENT ISSUES. Taylor & Francis, Inc., Philadelphia, PA, 82(4):244-260, (2019). https://doi.org/10.1080/15287394.2019.1587901

Impact/Purpose:

Non-targeted analysis (NTA) of breath-borne compounds can provide important information about environmental and occupational exposures to harmful compounds, including volatile organic compounds (VOCs) and polyaromatic hydrocarbons (PAHs). NTA is a rapidly evolving field requiring the harmonization of analytical instrumentation and data processing workflows to identify compounds from observed features.1,2,3 While NTA has frequently been employed using LC-MS instrumentation,2,4 some demonstrations of NTA with GC-MS are available. For example, Wang et al.5 used GC-MS to identify non-targeted metabolites in human plasma. Compound libraries alone are often not sufficient for accurate compound identification. Additional information such as the number of data sources and references in public databases as well as retention time (RT) prediction can be utilized to narrow down the list of potential compounds present in the samples.6,7 In the current work, both targeted and non-targeted analyses of firefighter breath samples were performed to identify compounds present in the samples that may be indicative of exposure. Although focused on occupational exposures, this work demonstrates the general value of expanding public health exposure assessment to chemicals not previously found in environmental scenarios of interest, especially at the community level, using NTA techniques.

Description:

A non-targeted analysis workflow was applied to analyze exhaled breath samples collected from firefighters pre- and post-structural fire suppression. Breath samples from firefighters functioning in attack and search positions were examined for target and non-target compounds in automated thermal desorption-GC/MS (ATD-GC/MS) selected ion monitoring (SIM)/scan mode and reviewed for prominent chemicals. Targeted chemicals included products of combustion such as benzene, toluene, xylenes, and polycyclic aromatic hydrocarbons (PAH) that serve as a standard assessment of exposure. Sixty unique chemical features representative of exogenous chemicals and endogenous compounds, including single-ring aromatics, polynuclear aromatic hydrocarbons, volatile sulfur-containing compounds, aldehydes, alkanes, and alkenes were identified using the non-targeted analysis workflow. Fifty-seven out of 60 non-targeted features changed by at least 50% from pre- to post-fire suppression activity in at least one subject, and 7 non-targeted features were found to exhibit significantly increased or decreased concentrations for all subjects as a group. This study is important for (1) alerting the firefighter community to potential new exposures, (2) expanding the current targeted list of toxicants, and (3) finding biomarkers of response to firefighting activity as reflected by changes in endogenous compounds. Data demonstrate that there are non-targeted compounds in firefighters’ breath that are indicative of environmental exposure despite the use of protective gear, and this information may be further utilized to improve the effectiveness of personal protective equipment.

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