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Current Research

1. Biomarkers of exposure to biomass smoke

Methoxypohenols are generated from the pyrolysis of the wood polymer lignin, therefore they are useful markers for exposure to woodsmoke. We have developed GC/MS methodology to measure methoxyphenols in air particulate and in urine samples. We have demonstrated associations between woodsmoke exposure and urinary methoxyphenol biomarkers in wildland firefighters, and in rural communities from Guatemala.

• Dills, R.L., Paulsen, M., Ahmad, J., Kalman, D.A., Simpson, C.D. Evaluation of Urinary Methoxyphenols as Biomarkers of Woodsmoke Exposure, Environ. Sci. Technol. 40(7): 2163-2170, 2006
  
• Clarke, M. Paulsen, M., Canuz, E., Smith, K.R. and Simpson, C.D. Urinary Methoxyphenol Biomarkers and Woodsmoke Exposure: Comparisons in Rural Guatemala with Personal CO and Kitchen CO, Levoglucosan, and PM2.5, Environ. Sci. Technol. 41(10): 3481-3487, 2007.
• Neitzel, R., Naeher, L.P., Paulsen, M., Dunn, K. Stock, A., and Simpson, C.D.  Biological Monitoring of Smoke Exposure among Wildland Firefighters: Comparison of Urinary Methoxyphenols with Personal Exposures to Carbon Monoxide, Particulate Matter and Levoglucosan, J. Exposure Sci. Environ. Epi., 19(4):349-358, 2009.

2. Biomarkers of exposure to diesel exhaust

Diesel exhaust is a major constituent of ambient particulate air pollution, and substantial occupational exposures to diesel exhaust exist (e.g miners, truck mechanics). Diesel exhaust is considered to be carcinogenic and to exacerbate allergic responses. In this project we aim to improve assessment of exposure to diesel exhaust by measuring levels of urinary metabolites of diesel-specific nitro-PAH (e.g. 1-nitro-pyrene metabolites).

• Toriba, A., Kitaoka, H., Dills, R., Mizukami, S., Tanabe, K., Takeuchi, N., Ueno, M., Kameda, T., Ning, T., Hayakawa, K., and Simpson, C.D. Identification and Quantification of 1-Nitropyrene Metabolites in Human Urine as a Proposed Biomarkers for Exposure to Diesel Exhaust, Chem. Res. Toxicol 20(7): 999-1007, 2007.

3. Use of molecular markers for measurement and source apportionment of particulate air pollution

Because different sources of air pollution show differential toxicity in humans, it is important to apportion exposure to air pollution among the different sources. We are studying the utility of source specific molecular markers to improve source apportionment of particulate air pollution

• Larson, T., Gould, T., Simpson, C.D., Claiborn, C., Lewtas, J., Wallace, L., and Liu, L.J.S. Source Apportionment of Indoor, Outdoor and Personal PM2.5 In Seattle, WA Using Positive Matrix Factorization, J. Air Waste Manage. Assoc. 54: 1175-1187, 2004.
• Ward, T.J., Hamilton, R., Dixon, R.W., Paulsen, M., Simpson, C.D. Characterization and Evaluation of Woodsmoke Tracers in PM: Results from the 2003 Montana Wildfire Season, Atmos. Environ. 40: 7005-7017, 2006.
• Miller-Schulze, J.P., Paulsen, M., Toriba,A., Tang,N., Hayakawa,K., Tamura,K., Dong,L., Zhang,X., and Simpson.C.D. Nitro Polycyclic Aromatic Hydrocarbons in Urban Air Particulate Collected in Shenyang, China and Their Relevance to Emission Sources and Atmospheric Conditions Environ. Sci. Technol. (in press: accepted, December, 2008)

4. Markers of oxidative stress associated with exposure to particulate air pollution

F2-isoprostanes (F2-iPs) are derived from the free-radical mediated oxidation of arachidonic acid. 3-nitrotyrosine (3NT) is generated in part from the reaction of peroxynitrite and tyrosine. Levels of both compounds are indicative of oxidative stress /in vivo/.

5. Biomarkers of exposure to organo-phoshporus pesticides.

Organo-phosphorus pesticides (OPs) have widespread commercial application. The current procedure used in Washington State to monitor workplace exposures involves measuring cholinesterase activity in workers' blood samples. We are developing an HPLC/MS/MS method to measure OP-cholinesterase adducts in plasma that will be more sensitive and specific to OP exposure than existing methods.

• New Methods for Measuring Exposure to Organophosphorus Pesticides

6. Use of Metabolomics to identify novel exposure biomarkers

Metabolomics’, can be defined as the "systematic study of the small-molecule metabolite profiles that result from exogenous stimuli, including exposure to environmental toxicants.” Metabolomics offers great promise for the development of early biomarkers of toxin exposure, and of disease resulting from those exposures. We are exploring proteomic and metabolomic approaches to identify novel biomarkers associated with exposure to organophosphorus pesticides.