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NEW METHODOLOGY FOR IDENTIFYING POTENTIAL HUMAN BIOMARKERS BY COLLECTION AND CONCENTRATION OF EXHALED BREATH CONDENSATE
Pleil, J D., M Colon, AND A B. Lindstrom. NEW METHODOLOGY FOR IDENTIFYING POTENTIAL HUMAN BIOMARKERS BY COLLECTION AND CONCENTRATION OF EXHALED BREATH CONDENSATE. Presented at Environmental Sampling and Analysis Seminar, Okinawa, Japan, July 8-22, 2001.
The objective of this task is to develop state-of-the-art methods for measuring xenobiotic compounds, to include the isolation of the analyte from the appropriate matrix (extraction), preconcentration (typically sorbent-based), and analysis via GC/MS and/or LC/MS. Once established, these methods will be applied in small scale pilot studies or demonstration projects. Particular emphasis will be placed on methods which are readily transferable to other laboratories, including those within the Human Exposure and Atmospheric Sciences Division (HEASD), the National Exposure Research Laboratory (NERL), other EPA Laboratories, Program Offices, Regions, and academic institutions.
Specific objectives of this task include the following:
1) Development of GC/MS and LC/MS methods for the measurement of key xenobiotic compounds and their metabolites (to include the pyrethroid pesticides, perfluorinated organic compounds, and the BFRs) in relevant environmental and biological matrices.
2) Development of efficient low cost methods for the extraction and clean up of these compounds collected from relevant matrices.
3) Determination of xenobiotic compound and metabolite concentrations in samples derived from laboratory and field monitoring studies to help assess exposures and evaluate associated risks.
In many studies of human exposure, the measurement of pollutant chemicals in the environment (air, water, food, soil, etc.) is being supplemented by their additional measurement in biological media such as human breath, blood, and urine. This allows an unambiguous confirmation of the identity and amount of the chemical exposure to the human subject. For volatile organic compounds (gaseous pollutants in air), breath is the simplest choice for the biological matrix because it is easy to get (especially compared to blood), it is easier to analyze trace gases in a gas phase (rather than liquid phase) matrix, and no infectious waste (needles, vials, leftover liquids) are generated.
The subsequent success of using breath as a "biological fluid" has created interest in measuring additional compounds that may serve as internally produced biomarkers of external chemical exposures which could serve as a simple, non-invasive exposure assessment tool for internal dose. Such biomarkers will most likely occur at very low concentrations compared to the exposure and will be very water soluble; these are two properties that make gas phase analysis difficult. We have developed a sampling and analytical method that accentuates the water soluble fraction of organic compounds in breath for GC-MS analysis. Multiple breaths are passed through special glassware at subambient temperature (-80C); upon heating to 37C, the condensed water is sparged with dry nitrogen into a standard 1-liter volume breath sampling container (SUMMA canister) also at -80C. When warmed to room temperature, the canister becomes positively pressurized and is then analyzed as a normal single breath sample, yet contains an elevated amount of the polar volatile organic compounds as trapped from 40 or 50 breaths. This allows more detailed analysis of the normally occurring metabolic products as well as putative biomarkers of exposure in breath.
To date, we have identified a variety of compounds in normal (healthy) adults that include C3 to C9 n-aldehydes, C3 and C4 branched aldehydes, benzaldehyde, various volatile alcohols including methanol, ethanol, butanol, 1- and 2-propanol, and methyl ethyl ketone. Additionally, variety of ketones, aldehydes, alcohols, terpenoids, ethers, acetates, etc. have been tentatively identified and work continues to unambiguously confirm as many compounds as possible. In the long run, we anticipate using patterns of endogenously produced compounds expressed in breath as an indicator of external exposure.
This work has been reviewed in accordance with the U.S. Environmental Protection Agency's peer and administrative review process and approved for presentation and publication. Mention of tradenames or commercial products does not constitute endorsement or recommendation for use.