Zheng (Jane) LI, Courtney d sandau pah and Combustion Exposure Biomarker Section


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Biomonitoring of Human Exposure to Biomass Burning -- A Proposed Collaboration with GA Tech

  • Zheng (Jane) Li, Courtney D Sandau

  • PAH and Combustion Exposure Biomarker Section

  • Organic Analytical Toxicology Branch

  • Division of Laboratory Sciences

  • National Center for Environmental Health

  • Centers for Disease Control and Prevention

  • Atlanta, GA 30341


What is Biomarker?

  • Biomarkers of exposure refer to cellular, biochemical, analytical, or molecular measures that are obtained from biological media such as tissues, cells, or fluids and are indicative of exposure to an agent.



What is Biomonitoring?

  • Assessment of internal dose exposure by measuring a toxicant, or its metabolite or reaction product (biomarker) in human blood, urine, saliva, adipose, or other tissue



Exposure and health effects pathway



Predicting levels of toxicants in people using environmental monitoring is very difficult and includes many assumptions



Biomonitoring provides unique information for --

  • The public health response to a known or suspected excessive exposure to a toxicant(s) or a pollutant(s).

  • Health research to determine what toxicants and what internal dose levels cause disease or death

  • Human data significantly decrease uncertainty in assessing human risk



National Report on Human Exposure to Environmental Chemicals (NHANES)



PAH & Combustion Exposure Biomarker Laboratory

  • CDC currently monitors Group A (2-4 aromatic ring) PAH-OH metabolites, conducted in our laboratory

  • Newly developed method has LOD for most of 23 OH-PAHs at low ppt

  • Expanding to include metabolites of Group B (5 and more aromatic ring, e.g. OH-benzo[a]pyrene), and amino-PAHs, metabolites of NO2-PAH.

  • Initializing and developing methods to monitor human exposure to biomass burning



Exposure Study on Biomass Burning – a Challenge

  • Large emissions

  • Numerous classes and uncountable chemicals released in biomass fires

  • Various emission profiles from different burning sources

  • Particles and aerosols with organic compounds condensed on the surface can be transported over long distance



Emissions From Biomass Burning



Potential Markers for Biomass Burning -- Methoxyphenols

  • One major group of compounds studied as biomarkers

  • Softwood guaiacyl compds

  • Hardwood syringyl compds

  • A urinary assay of methoxyphenols for biomonitoring wood smoke exposure has been developed



Potential Markers for Biomass Burning -- PAHs

  • A major group of organic pollutants formed during incomplete combustion

  • Mutagenic and carcinogenic

  • Most abundant ones are pyrene, phenanthrene, fluoranthene, benzo(a/e)pyrene, chrysene, etc.

  • Alkyl-PAHs, e.g. pimanthrene and retene, suggested to be the major source specific biomarkers in pine smoke



PAHs, Source-specific Markers

  • Relative amounts of alkyl-PAHs to the parent PAHs – petrogenic source vs. combustion source

  • Relative amounts of unstable or kinetic PAHs to the more stable or thermodynamic PAHs – combustion or anthropogenic input

  • Acenaphthene and acenaphthylene – combustion source; cadalene and retene – plant source



Analytical Techniques

  • Extraction

  • Solid phase extraction (SPE) or silica/florisil column for further sample clean up

  • Gas chromatography/mass spectrometry

    • GC/Time-of-flight (TOF) MS
    • GC x GC/TOFMS
    • GC/high-resolution MS
  • Isotope dilution for precise and accurate measurements



Identification of Unknown Markers -- GC/TOFMS



Identification of Unknowns -- GC x GC/TOFMS

  • 4-Dimensional GC x GC-TOFMS

  • Two distinctive separation mechanisms, such as polar and non-polar

  • Improving resolution, reducing chromatographic co-elution – more accurate analyte identifications

  • Ideal for obtaining maximum information from complex samples



GC x GC/TOFMS



GC x GC/TOFMS



Quantitation – GC/HRMS



Objectives

  • Identify source-specific markers for biomass combustions

    • Verify and confirm reported markers
    • Search for new ones
  • Identify optimal metabolites in human body for biomonitoring

  • Perform studies on populations exposed to biomass burning



Possible Population/Field Studies

  • Exposure assessment to indoor air pollution caused by domestic biomass burning in developing countries, e.g. China, India, etc.

  • Occupational and residential exposure to forest fires

  • Exposure study on large scale agricultural burning, e.g. sugarcane burning in Brazil and Costa Rica






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