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Biological Sciences Staff information

Chuck Timchalk

Health Impacts & Exposure Science


Dr. Timchalk received a B. S. in Biology in 1978 from the State University of New York, and a Ph.D. in 1986 from the Department of Pharmacology and Toxicology, The Albany Medical College. He is currently certified as a Diplomat of the American Board of Toxicology. In 1986 he joined the Dow Chemical Company as a post-doctoral fellow and while at Dow he was a Research and Technical Leader within the Pharmacokinetics and Metabolism group prior to accepting his current position. In 1997 he joined PNNL as a Staff Scientist. In this position he is continuing to pursue his interest in human health research. Dr. Timchalk is currently the principal investigator or co-investigator on several DHHS/NIH grants and DoD Cooperative Biological Engagement Program. His research has been published in over 90 peer reviewed manuscripts, and has resulted in numerous patents and book chapters. He has likewise provided support on technical review and numerous advisory committees. He has held a number of leadership positions (including President) within the Society of Toxicology, Biological Modeling Specialty Section. Over the course of his career Dr. Timchalk has been acknowledged both for his professional accomplishments and for his ongoing interest in supporting the development of young scientists. His research has been recognized by awards from the Environmental Business Journal (Technical Merit award, 2001), and R&D 100 Nomination (2004). In addition, he received the Department of Energy, Office of Science Outstanding Mentor Award recipient (2002); and the Pacific Northwest National Laboratory, Chester I. Cooper Mentor of the Year Award (2003).

Research Interests

  • Global health: providing training to scientist within low- & middle-income countries on programmatic grant development to achieve sustainability in a global research environment.
  • Development of multidisciplinary integrated research programs and teams to advance exposure assessment and toxicology through the development and implementation of novel technologies.
  • Diagnostic non-invasive biological monitoring (development/validation of sensors).
  • Development of physiologically based pharmacokinetic and pharmacodynamic model for single agents and mixtures.
  • Life-stage specific sensitivities to toxic agents: modeling early development.

Education and Credentials

  • 1982 - 1986 Doctor of Philosophy (Ph.D.) The Albany Medical College of Union University, Department of Pharmacology & Toxicology, Albany, NY 12208 Emphasis: Toxicology/ Pharmacology
  • 1974 - 1978 Bachelor of Science (B. S.) State University of New York at Oneonta, Oneonta, NY, 13820. Major: Biology Minor: Chemistry
  • Diplomat of the American Board of Toxicology, DABT (1994 - present) Re-certified (2000-2004; 2005-2009; 2010-2014)

Affiliations and Professional Service

  • Society of Toxicology- Full Member (1987- present)
  • Society of Toxicology- Biological Modeling Specialty Section (2000-present)
  • Society of Toxicology- Mixtures Specialty Section (2010-present)
  • Society of Toxicology- Councilor, Biological Modeling Specialty Section (2002-2004)
  • Society of Toxicology- Vice President-Elect, Biological Modeling Specialty Section (2004)
  • Society of Toxicology- Vice President, Biological Modeling Specialty Section (2005)
  • Society of Toxicology- President, Biological Modeling Specialty Section (2006)
  • Society of Toxicology- Past President, Biological Modeling Specialty Section (2007)
  • Sigma Xi, Scientific Research Society- Full Member (1986 - 2008)
  • International Society for the Study of Xenobiotics (1995 - present)
  • Pacific Northwest Society of Toxicology (1999- present)
  • Michigan Society of Toxicology (1995 - 1997)

Awards and Recognitions

  • Albany Medical College Trustees Scholarship (1982 - 1986)
  • National Research Service Award, NIEHS 5T32 ES07058-05 (1982 - 1983)
  • Albany Medical College Teaching Assistantship (1983 - 1986)
  • Albany Medical College Student Travel Program Grant (1985)
  • Society of Toxicology, Student Travel Award (1985 - 1986)
  • Society of Toxicology, Risk Assessment Specialty Section Best Paper Award (1999)
  • Environmental Business Journal Technical Merit Award " Saliva Biomonitor (2001)
  • Department of Energy, Office of Science Outstanding Mentor Award recipient (2002)
  • Pacific Northwest National Laboratory, Chester I. Cooper Mentor of the Year Award (2003)
  • R&D 100 Nomination, Pacific Northwest National Laboratory " Saliva Biomonitoring Technology (2004)
  • Environmental Business Journal Technical Merit Award " Insecticide Biosensor (2006)
  • Society of Toxicology, Biological Modeling Specialty Section- Best Paper Award (2011) - Hinderliter et al Reg. Tox. and Pharm., 61(1): 82-92, PMID: 21722690.
  • Society of Toxicology, Biological Modeling Specialty Section- Best Paper Award (2012) " Corley et al Toxicol. Sci. 128(2): 500-516, PMID: 22584687

PNNL Publications


  • Poet TS, C Timchalk, MJ Bartels, JN Smith, R Mcdougal, D Juberg, and PS Price. 2017. "Use of a probabilistic PBPK/PD model to calculate Data Derived Extrapolation Factors for chlorpyrifos." Regulatory Toxicology and Pharmacology 86:59-73.  doi:10.1016/j.yrtph.2017.02.014
  • Smith JN, ZA Carver, TJ Weber, and C Timchalk. 2017. "Predicting Transport of 3,5,6-Trichloro-2-pyridinol into Saliva Using a Combination Experimental and Computational Approach." Toxicological Sciences 157(2):438-450.  doi:10.1093/toxsci/kfx055
  • Timchalk C, TJ Weber, and JN Smith. 2017. "The Need for Non- or Minimally-Invasive Biomonitoring Strategies and the Development of Pharmacokinetic/Pharmacodynamic Models for Quantification." Current Opinion in Toxicology 4:28-34.  doi:10.1016/j.cotox.2017.03.003


  • Corley RA, S Kabilan, AP Kuprat, JP Carson, RE Jacob, KR Minard, JG Teeguarden, C Timchalk, S Pipavath, RW Glenny, and DR Einstein. 2015. "COMPARATIVE RISKS OF ALDEHYDE CONSTITUENTS IN CIGARETTE SMOKE USING TRANSIENT COMPUTATIONAL FLUID DYNAMICS/PHYSIOLOGICALLY BASED PHARMACOKINETIC MODELS OF THE RAT AND HUMAN RESPIRATORY TRACTS." Toxicological Sciences 146(1):65-88.  doi:10.1093/toxsci/kfv071
  • Timchalk C, TJ Weber, and JN Smith. 2015. "Computational Strategy for Quantifying Human Pesticide Exposure based upon a Saliva Measurement." Frontiers in Pharmacology 6:Article No. 115.  doi:10.3389/fphar.2015.00115


  • Smith JN, PM Hinderliter, C Timchalk, MJ Bartels, and TS Poet. 2014. "A Human Life-Stage Physiologically Based Pharmacokinetic and Pharmacodynamic Model for Chlorpyrifos: Development and Validation." Regulatory Toxicology and Pharmacology 69(3):580-597.  doi:10.1016/j.yrtph.2013.10.005


  • Teeguarden JG, C Housand, JN Smith, PM Hinderliter, R Gunawan, and C Timchalk. 2013. "A Multi-Route Model of Nicotine-Cotinine Pharmacokinetics, Pharmacodynamics and Brain Nicotinic Acetylcholine Receptor Binding in Humans." Regulatory Toxicology and Pharmacology 65(1):12-28.  doi:10.1016/J.YRTPH.2012.10.007
  • Lanekoff IT, M Thomas, JP Carson, JN Smith, C Timchalk, and J Laskin. 2013. "Imaging Nicotine in Rat Brain Tissue by Use of Nanospray Desorption Electrospray Ionization Mass Spectrometry." Analytical Chemistry 85(2):882-889.  doi:10.1021/ac302308p
  • Zhang W, Y Tang, D Du, JN Smith, C Timchalk, D Liu, and Y Lin. 2013. "Direct analysis of trichloropyridinol in human saliva using an Au nanoparticles-based immunochromatographic test strip for biomonitoring of exposure to chlorpyrifos." Talanta 114:261-267.  doi:10.1016/j.talanta.2013.06.012


  • Corley RA, S Kabilan, AP Kuprat, JP Carson, KR Minard, RE Jacob, C Timchalk, RW Glenny, S Pipavath, TC Cox, C Wallis, R Larson, M Fanucchi, E Postlewait, and DR Einstein. 2012. "COMPARATIVE COMPUTATIONAL MODELING OF AIRFLOWS AND VAPOR DOSIMETY IN THE RESPIRATORY TRACTS OF RAT, MONKEY, AND HUMAN." Toxicological Sciences 128(2):500-516.  doi:10.1093/toxsci/kfs168
  • Smith JN, J Wang, Y Lin, EM Klohe, and C Timchalk. 2012. "Pharmacokinetics and Pharmacodynamics of Chlorpyrifos and 3,5,6-Trichloro-2-pyridinol in Rat Saliva After Chlorpyrifos Administration." Toxicological Sciences 130(2):245-256.  doi:10.1093/toxsci/kfs251
  • Timchalk C, JN Smith, AL Hjerpe, TS Poet, and SK Lee. 2012. "Regional Brain Dosimetry for the Organophosphorus Insecticide Chlorpyrifos in the Preweanling Rat." Chapter 13 in Parameters for Pesticide QSAR and PBPK/PD Models for Human Risk Assessment. ACS Symposium Series, vol. 1099, ed. JB Knaak, C Timchalk and R Tornero-Velez, pp. 195-213.  American Chemical Society, Washington DC. 


  • Hinderliter PM, PS Price, MJ Bartels, C Timchalk, and TS Poet. 2011. "Development of a Source-to-Outcome Model for Dietary Exposures to Insecticide Residues: An Example Using Chlorpyrifos." Regulatory Toxicology and Pharmacology 61(1):82-92.  doi:10.1016/j.yrtph.2011.06.004
  • Smith JN, C Timchalk, MJ Bartels, and TS Poet. 2011. "In Vitro Age-Dependent Enzymatic Metabolism of Chlorpyrifos and Chlorpyrifos-Oxon in Human Hepatic Microsomes and Chlorpyrifos-Oxon in Plasma." Drug Metabolism and Disposition 39(8):1353-1362.  doi:10.1124/dmd.111.038745
  • Du D, J Wang, L Wang, D Lu, JN Smith, C Timchalk, and Y Lin. 2011. "Magnetic Electrochemical Sensing Platform for Biomonitoring of Exposure to Organophosphorus Pesticides and Nerve Agents Based on Simultaneous Measurement of Total Enzyme Amount and Enzyme Activity ." Analytical Chemistry 83(10):3770-3777.  doi:10.1021/ac200217d
  • Lee SK, TS Poet, JN Smith, AL Hjerpe, R Gunawan, and C Timchalk. 2011. "IMPACT OF REPEATED NICOTINE AND ALCOHOL COEXPOSURE ON IN VITRO AND IN VIVO CHLORPYRIFOS DOSIMETRY AND CHOLINESTERASE INHIBITION." Journal of Toxicology and Environmental Health Part A 74(20):1334-50. 
  • Lu D, J Wang, L Wang, D Du, C Timchalk, RC Barry, and Y Lin. 2011. "A novel nanoparticle-based disposable electrochemical immunosensor for diagnosis of exposure to toxic organophosphorus agents." Advanced Functional Materials 21(22):4371-4378.  doi:10.1002/adfm.201100616
  • Price PS, KD Schnelle, CB Cleveland, MJ Bartels, PM Hinderliter, C Timchalk, and TS Poet. 2011. "Application of a Source-to-Outcome Model for the Assessment of Health Impacts from Dietary Exposures to Insecticide Residues." Environmental Health Perspectives 61(1):23-31.  doi:10.1016/j.yrtph.2011.05.009
  • Wang L, D Du, D Lu, CT Lin, JN Smith, C Timchalk, F Liu, J Wang, and Y Lin. 2011. "Enzyme-linked immunosorbent assay for detection of organophosphorylated butyrylcholinesterase: A biomarker of exposure to organophosphate agents." Analytica Chimica Acta 693(1-2):1-6. 
  • Wang L, D Lu, J Wang, D Du, Z Zou, H Wang, JN Smith, C Timchalk, F Liu, and Y Lin. 2011. "A Novel Immunochromatographic Electrochemical Biosensor for Highly Sensitive and Selective Detection of Trichloropyridinol, a Biomarker of Exposure to Chlorpyrifos." Biosensors and Bioelectronics 26(6):2835-2840 .  doi:10.1016/j.bios.2010.11.008


  • Busby-Hjerpe AL, JA Campbell, JN Smith, S Lee, TS Poet, D Barr, and C Timchalk. 2010. "Comparative Pharmacokinetics of Chlorpyrifos versus its Major Metabolites Following Oral Administration in the Rat." Toxicology 268(1-2):55-63.  doi:10.1016/j.tox.2009.11.022
  • Timchalk C, JA Creim, V Sukwarotwat, RJ Wiacek, RS Addleman, GE Fryxell, and W Yantasee. 2010. "In Vitro and In Vivo Evaluation of a Novel Ferrocyanide Functionalized Nanopourous Silica Decorporation Agent for Cesium in Rats ." Health Physics 99(3):420-429.  doi:10.1097/HP.0b013e3181bca9b0
  • Timchalk C. 2010. "Biomonitoring of Pesticides: Pharmacokinetcs of Organophosphorus and Carbamate Insecticides." Chapter 19 in Anticholinesterase Pesticides: Metabolism, Neurotoxicity and Epidemiology, ed. T Satoh and RC Gupta, pp. 267-287.  John Wiley & Sons, Hoboken, NJ. 
  • Timchalk C. 2010. "Organophosphorus Insecticide Pharmacokinetics." Chapter 66 in Hayes' Handbook of Pesticide Toxicology, 3rd ed, vol. 2, ed. RI Krieger, pp. 1409-1433.  Academic Press, London, United Kingdom. 
  • Lee S, TS Poet, JN Smith, AL Busby-Hjerpe, and C Timchalk. 2010. "Effect of In Vivo Nicotine Exposure on Chlorpyrifos Pharmacokinetics and Pharmacodynamics in Rats ." Chemico-Biological Interactions 184(3):449-457. 
  • Lee SK, TS Poet, JN Smith, AL Busby-Hjerpe, and C Timchalk. 2010. "Effect of in vivo nicotine exposure on chlorpyrifos pharmacokinetics and pharmacodynamics in rats." Chemico-Biological Interactions 184(3):449-457.  doi:10.1016/j.cbi.2010.01.024
  • Sangvanich T, V Sukwarotwat, RJ Wiacek, RM Grudzien, GE Fryxell, RS Addleman, C Timchalk, and W Yantasee. 2010. "Selective Capture of Cesium and Thallium from Natural Waters and Simulated Wastes with Copper Ferrocyanide Functionalized Mesoporous Silica." Journal of Hazardous Materials 182(1-3):225-231.  doi:10.1016/j.jhazmat.2010.06.019
  • Smith JN, J Wang, Y Lin, and C Timchalk. 2010. "Pharmacokinetics of the Chlorpyrifos Metabolite 3,5,6-Trichloro-2-Pyridinol (TCPy) in Rat Saliva." Toxicological Sciences 132(2):315-325. 
  • Still K, D Gardner, R Snyder, T Anderson, J Honeyman, and C Timchalk. 2010. "Development of Occupational Exposure Limits for the Hanford Tank Farms." Inhalation Toxicology 22(5):427-444.  doi:10.3109/08958371003592297
  • Timchalk C, PM Hinderliter, and TS Poet. 2010. "Modeling Cholinesterase Inhibition." Chapter 6 in Quantitative Modeling in Toxicology, ed. K, Krishnan and M Andersen, pp. 137-165.  John Wiley & Sons, Ltd, New York. 
  • Yantasee W, RD Rutledge, W Chouyyok, V Sukwarotwat, G Orr, CL Warner, MG Warner, GE Fryxell, RJ Wiacek, C Timchalk, and RS Addleman. 2010. "Functionalized Nanoporous Silica for Removal of Heavy Metals from Biological Systems; Adsorption and Application." ACS Applied Materials & Interfaces 2(10):2749-2758.  doi:10.1021/am100616b
  • Yantasee W, T Sangvanich, JA Creim, K Pattamakomsan, RJ Wiacek, GE Fryxell, RS Addleman, and C Timchalk. 2010. "Functional Sorbents for Selective Capture of Plutonium, Americium, Uranium, and Thorium in Blood." Health Physics 99(3):413-419. 
  • Zou Z, D Du, J Wang, JN Smith, C Timchalk, YQ Li, and Y Lin. 2010. "Quantum Dot-Based Immunochromatographic Fluorescent Biosensor for Biomonitoring Trichloropyridinol, a Biomarker of Exposure to Chlorpyrifos." Analytical Chemistry 82(12):5125-5133.  doi:10.1021/ac100260m


  • Barry RC, Y Lin, J Wang, G Liu, and C Timchalk. 2009. "Nanotechnology-Based Electrochemical Sensors for Biomonitoring Chemical Exposures ." Journal of Exposure Science and Environmental Epidemiology 19:1-18.  doi:10.1038/jes.2008.71
  • Du D, J Wang, JN Smith, C Timchalk, and Y Lin. 2009. "Biomonitoring of Organophosphorus Agent Exposure by Reactivation of Cholinesterase Enzyme Based on Carbon Nanotube-Enhanced Flow-Injection Amperometric Detection ." Analytical Chemistry 81(22):9314-9320. 
  • Garabrant DH, LL Aylward, S Berent, Q Chen, C Timchalk, CJ Burns, SM Hays, and JW Albers. 2009. "Cholinesterase inhibition in chlorpyrifos workers: Characterization of biomarkers of exposure and response in relation to urinary TCPy." Journal of Exposure Science and Environmental Epidemiology 19(7):634-642.  doi:10.1038/jes.2008.51
  • Lee S, AL Busby, C Timchalk, and TS Poet. 2009. "Effects of Nicotine Exposure on In Vitro Metabolism of Chlorpyrifos in Male Sprague-Dawley Rats." Journal of Toxicology and Environmental Health Part A 72(2):74-82.  doi:10.1080/15287390802477288
  • Lin Y, J Wang, G Liu, and C Timchalk. 2009. "Portable Analytical Systems for On-Site Diagnosis of Exposure to Pesticides and Nerve Agents." Chapter 7 in Nanoscience and Nanotechnology for Chemical and Biological Defense, ACS Sympoisum Series, vol. 1016, ed. R. Nagarajan, W. Zukas, T. A. Hatton, S. Lee, pp. 85-98.  Oxford University Press, DC. 
  • Lowe ER, TS Poet, DL Rick, MS Marty, JL Mattson, C Timchalk, and MJ Bartels. 2009. "The Effect of Plasma Lipids on the Pharmacokinetics of Chlorpyrifos and the Impact on Interpretation of Blood Biomonioring Data." Toxicological Sciences 108(2):258-272. 
  • Lowe ER, TS Poet, DL Rick, MS Marty, JL Mattsson, C Timchalk, and MJ Bartels. 2009. "The effect of plasma lipids on the pharmacokinetics of chlorpyrifos and the impact on interpretation of blood biomonitoring data. ." Toxicological Sciences 108(2):258-272.  doi:10.1093/toxsci/kfp034
  • Smith JN, JA Campbell, AL Busby-Hjerpe, S Lee, TS Poet, D Barr, and C Timchalk. 2009. "Comparative chlorpyrifos pharmacokinetics via multiple routes of exposure and vehicles of administration in the adult rat." Toxicology 261(1-2):47-58.  doi:10.1016/j.tox.2009.04.041


  • Jacob RE, KR Minard, GJ Laicher, and C Timchalk. 2008. "3D He-3 diffusion MRI as a local in vivo morphometric tool to evaluate emphysematous rat lungs." Journal of Applied Physiology 105:1291-1300.  doi:10.1152/japplphysiol.90375.2008
  • Wang J, C Timchalk, and Y Lin. 2008. "Carbon Nanotube-Based Electrochemical Sensor for Assay of Salivary Cholinesterase Enzyme Activity: An Exposure Biomarker of Organophosphate Pesticides and Nerve Agents." Environmental Science & Technology 42(7):2688-2693.  doi:10.1021/es702335y
  • Liu G, J Wang, RC Barry, CE Petersen, C Timchalk, PL Gassman, and Y Lin. 2008. "Nanoparticle-Based Electrochemical Immunosensor for the Detection of Phosphorylated Acetylcholinesterase: An Exposure Biomarker of Organophosphate Pesticides and Nerve AgentsOrganophosphate Pesticides and Nerve Agents ." Chemistry - a European Journal 14(32):9951-9959.  doi:10.1002/chem.200800412
  • Timchalk C, and TS Poet. 2008. "Development of a Physiologically Based Pharmacokinetic and Pharmacodynamic Model to Determine Dosimetry and Cholinesterase Inhibition for a Binary Mixture of Chlorpyrifos and Diazinon in the Rat." NeuroToxicology 29(3 Sp Iss):428-443.  doi:10.1016/j.neuro.2008.02.004
  • Wang H, J Wang, C Timchalk, and Y Lin. 2008. "Magnetic Electrochemical Immunoassays with Quantum Dot Labels for Detection of Phosphorylated Acetylcholinesterase in Plasma." Analytical Chemistry 80(22):8477-8484.  doi:10.1021/ac801211s
  • Yantasee W, B Charnhattakorn, GE Fryxell, Y Lin, C Timchalk, and RS Addleman. 2008. "Detection of Cd, Pb, and Cu in non-pretreated natural waters and urine with thiol functionalized mesoporous silica and Nafion composite electrodes." Analytica Chimica Acta (620):55-63.  doi:10.1016/j.aca.2008.05.029
  • Yantasee W, K Hongsirikarn, CL Warner, D Choi, T Sangvanich, MB Toloczko, MG Warner, GE Fryxell, RS Addleman, and C Timchalk. 2008. "Direct detection of Pb in urine and Cd, Pb, Cu, and Ag in natural waters using electrochemical sensors immobilized with DMSA functionalized magnetic nanoparticles." The Analyst 133(3):348-355.  doi:10.1039/b711199a


  • Timchalk C, JA Campbell, G Liu, Y Lin, and AA Kousba. 2007. "Development of a Non-Invasive Biomonitoring Approach to Determine Exposure to the Organophosphorus Insecticide Chlorpyrifos in Rat Saliva." Toxicology and Applied Pharmacology 219(2-3):217-225.  doi:10.1016/j.taap.2006.10.002
  • Kousba AA, TS Poet, and C Timchalk. 2007. "AGE-RELATED BRAIN CHOLINESTERASE INHIBITION KINETICS FOLLOWING IN VITRO INCUBATION WITH CHLORPYRIFOS-OXON AND DIAZINON-OXON." Toxicological Sciences 95(1):147-155.  doi:doi:10.1093/toxsci/kfl123
  • Marty MS, JY Domoradzki, SC Hansen, C Timchalk, MJ Bartels, and JL Mattsson. 2007. "The Effect of Route, Vehicle, and Divided Doses on the Pharmacokinetics of Chlorpyrifos and its Metabolite Trichloropyridinol in Neonatal Sprague-Dawley Rats." Toxicological Sciences 100(2):360-373.  doi:10.1093/toxsci/kfm239
  • Timchalk C, AL Busby, JA Campbell, LL Needham, and D Barr. 2007. "Comparative Pharmacokinetics of the Organophosphorus Insecticide Chlorpyrifos and its Major Metabolites Diethylphosphate, Diethylthiophosphate and 3,5,6-Trichloro-2-pyridinol in the Rat." Toxicology 237(1-3):145-157.  doi:10.1016/j.tox.2007.05.007
  • Timchalk C, AA Kousba, and TS Poet. 2007. "An Age-Dependent Physiologically-Based Pharmacokinetic/Pharmacodynamic Model for the Organophosphorus Insecticide Chlorpyrifos in the Preweanling Rat." Toxicological Sciences 98(2):348-365.  doi:10.1093/toxsci/kfm119
  • Yantasee W, C Timchalk, and Y Lin. 2007. "Microanalyzer for Biomonitoring of Lead (Pb) in Blood and Urine ." Analytical and Bioanalytical Chemistry 387(1):335-341.  doi:10.1007/s00216-006-0940-1
  • Yantasee W, CL Warner, T Sangvanich, RS Addleman, TG Carter, RJ Wiacek, GE Fryxell, C Timchalk, and MG Warner. 2007. "Removal of Heavy Metals from Aqueous Systems with Thiol Functionalized Superparamagnetic Nanoparticles." Environmental Science & Technology 41(14):p.5114-5119.  doi:10.1021/es0705238
  • Yantasee W, Y Lin, K Hongsirikarn, GE Fryxell, RS Addleman, and C Timchalk. 2007. "Electrochemical Sensors for the Detection of Lead and Other Toxic Heavy Metals: The Next Generation of Personal Exposure Biomonitors." Environmental Health Perspectives 115(12):1683-1690. 


  • Poet TS, and C Timchalk. 2006. Proposed Occupational Exposure Limits for Non-Carcinogenic Hanford Waste Tank Vapor ChemicalsPNNL-15736, Pacific Northwest National Laboratory, Richland, WA. 
  • Timchalk C, Y Lin, KK Weitz, H Wu, RA Gies, DA Moore, and W Yantasee. 2006. "Disposition of Lead (Pb) in Saliva and Blood of Sprague-Dawley Rats Following a Single or Repeated Oral Exposure to Pb-Acetate." Toxicology 222(1-2):86-94.  doi:10.1016/j.tox.2006.01.030
  • Barton HA, TP Pastoor, K Baetcke, JE Chambers, J Diliberto, NG Doerrer, JH Driver, CE Hastings, S Iyengar, R Krieger, B Stahl, and C Timchalk. 2006. "The Acquisition and Application of Absorption, Distribution, Metabolism, and Excretion (ADME) Data in Agricultural Chemical Safety Assessments." Critical Reviews in Toxicology 36(1):9-35. 
  • Liu G, C Timchalk, and Y Lin. 2006. "Bioelectrochemical Magnetic Immunosensing of Trichloropyridinol: A Potential Insecticide Biomarker." Electroanalysis 18(16):1605-1613. 
  • Minard KR, DR Einstein, RE Jacob, S Kabilan, AP Kuprat, C Timchalk, LL Trease, and RA Corley. 2006. "Application of Magnetic Resonance (MR) Imaging for the Development and Validation of Computational Fluid Dynamic (CFD) Models of the Rat Respiratory System." Inhalation Toxicology 18(10):787-794.  doi: 10.1080/08958370600748729
  • Timchalk C, TS Poet, and AA Kousba. 2006. "Age-dependent pharmacokinetic and pharmacodynamic response in preweanling rats following oral exposure to the organophosphorus insecticide chlorpyrifos ." Toxicology 220(1):13-25.  doi:10.1016/j.tox.2005.11.011


  • Campbell JA, C Timchalk, AA Kousba, H Wu, BR Valenzuela, and EW Hoppe. 2005. "Negative Ion Chemical Ionization Mass Spectrometry for the Analysis of 3,5,6-trichloro-2-pyridinol in Saliva of Rats Exposed to Chlorpyrifos." Analytical Letters 38(6):939-949. 
  • Cole TB, BJ Walter, DM Shih, AD Tward, AJ Lusis, C Timchalk, RJ Richter, LG Costa, and CE Furlong. 2005. "Toxicity of chlorpyrifos and chlorpyrifos oxon in a transgenic mouse model of the human paraoxonase (PON1) Q192R polymorphism." Pharmacogenetics and Genomics 58(8):589-598. 
  • Furlong CE, TB Cole, BJ Walter, DM Shih, A Tward, AJ Lusis, C Timchalk, RJ Richter, and LG Costa. 2005. "Paraoxonase 1 (PON1) Status and Risk of Insecticide Exposure." Journal of Biochemical and Molecular Toxicology 19(3):182-183.  doi:10.1002/jbt.20079
  • Liu G, SL Riechers, C Timchalk, and Y Lin. 2005. "Sequential Injection/Electrochemical Immunoassay for Quantifying the Pesticide Metabolite 3, 5, 6-Trichloro-2-Pyridinol." Electrochemistry Communications 7(12):1463-1470. 
  • Minard KR, C Timchalk, and RA Corley. 2005. "T2-Shortening of 3He Gas by Magnetic Microspheres." Journal of Magnetic Resonance 173(1):90-96. 
  • Slikker W, JF Young, RA Corley, DC Dorman, RB Conolly, T Knudsen, BL Erstad, RH Luecke, EM Faustman, C Timchalk, and DR Mattison. 2005. "Improving Predictive Modeling in Pediatric Drug Development: Pharmacokinetics, Pharmacodynamics, and Mechanistic Modeling." In NPA Workshop: PBPK/PD Models for Developing Humans: Risk Assessment Strategies and Research Recommendations. Published in Annals of the New York Academy of Science, vol. 1053, pp. 505-518.  New York Academy of Sciences, New York.  doi:10.1196/annals.1344.044
  • Timchalk C, TS Poet, MN Hinman, AL Busby, and AA Kousba. 2005. "PHARMACOKINETIC AND PHARMACODYNAMIC INTERACTION FOR A BINARY MIXTURE OF CHLORPYRIFOS AND DIAZINON IN THE RAT." Toxicology and Applied Pharmacology 205(1):31-42. 
  • Yantasee W, C Timchalk, GE Fryxell, BP Dockendorff, and Y Lin. 2005. "Automated portable analyzer for lead(II) based on sequential flow injection and nanostructured electrochemical sensors ." Talanta 68(2):256-261. 
  • Yantasee W, C Timchalk, KK Weitz, DA Moore, and Y Lin. 2005. "Optimization of A Portable Microanalytical System to Reduce Electrode Fouling from Proteins Associated with Biomonitoring of Lead (Pb) in Saliva." Talanta 67(3):617-624. 
  • Yantasee W, LA Deibler, GE Fryxell, C Timchalk, and Y Lin. 2005. "Screen-Printed Electrodes Modified with Functionalized Mesoporous Silica for Voltammetric Analysis of Toxic Metal Ions." Electrochemistry Communications 7(11):1170-1176.  doi:10.1016/j.elecom.2005.08.018


  • Poet TS, AA Kousba, SL Dennison, and C Timchalk. 2004. "Physiologically Based Pharmacokinetic/Pharmacodynamic Model for the Organophosphorus Pesticide Diazinon." NeuroToxicology 25(6):1013-1030.  doi:10.1016/j.neuro.2004.03.002
  • Timchalk C. 2004. "Comparative Inter-Species Pharmacokinetics of Phenoxyacetic Acid Herbicides and Related Organic Acids. Evidence that the Dog is Not a Relevant Species for Evaluation of Human Health Risk. ." Toxicology 200(1):1-19. 
  • Busby AL, AA Kousba, and C Timchalk. 2004. "The In Vivo Quantitation of Diazinon, Chlorpyrifos and their Major Metabolites in Rat Blood for the Refinement of a Physiologically-based Pharmacokinetic/pharmacodynamic Models." Journal of Undergraduate Research Volume IV, 2004:36-40. 
  • Kousba AA, LG Sultatos, TS Poet, and C Timchalk. 2004. "Comparison of Chlorpyrifos-Oxon and Paraoxon Acetylcholinesterase Inhibition Dynamics: Potential role of a peripheral binding site ." Toxicological Sciences 80(2):239-248. 
  • Timchalk C, TS Poet, AA Kousba, JA Campbell, and Y Lin. 2004. "Noninvasive Biomonitoring Approaches to Determine Dosimetry and Risk Following Acute Chemical Exposure: Analysis of Lead or Organophosphate Insecticide in Saliva ." Journal of Toxicology and Environmental Health Part A 67:635-650. 


  • Poet TS, H Wu, AA Kousba, and C Timchalk. 2003. "In Vitro Rat Hepatic and Intestinal Metabolism of the Organophosphate Pesticides Chlorpyrifos and Diazinon." Toxicological Sciences 72(2):193-200. 
  • Kousba AA, TS Poet, and C Timchalk. 2003. "Characterization of the In Vitro Kinetic Interaction of Chlorpyrifos-Oxon with Rat Salivary Cholinesterase: A Potential Biomonitoring Matrix." Toxicology 188(2-3):219-232. 
  • Thrall KD, RE Schwartz, KK Weitz, JJ Soelberg, GL Foureman, JD Prah, and C Timchalk. 2003. "A Real-time Method to Evaluate the Nasal Deposition and Clearance of Acetone in the Human Volunteer." Inhalation Toxicology 15(6):523-538. 


  • Lin Y, C Timchalk, DW Matson, H Wu, and KD Thrall. 2001. "Integrated Microfluidics/Electrochemical Sensor System for Monitoring of Environmental Exposures to Lead and Chlorophenols." Biomedical Microdevices 3(4):331-338. 
  • Timchalk C, TS Poet, Y Lin, KK Weitz, R Zhao, and KD Thrall. 2001. "Development of an Integrated Micro-Analytical System for Lead in Saliva and Linkage to a Physiologically Based Pharmacokinetic Model Describing Lead Saliva Secretion ." American Industrial Hygiene Association Journal 62(3):295-302. 
  • Timchalk C, HE Trease, LL Trease, KR Minard, and RA Corley. 2001. "Potential Technology for Studying Dosimetry and Response to Airborne Chemical and Biological Pollutants." Toxicology and Industrial Health 17(5-10):270-6. 


  • Lin Y, DW Matson, WD Bennett, KD Thrall, and C Timchalk. 2000. "Integrated Microfluidics/Electrochemical Sensor System for Field-Monitoring of Toxic Metals ." In Microreaction technology: industrial prospects: IMRET 3 : proceedings of the Third International Conference on Microreaction Technology , ed. W. Ehrfeld, pp. 588-596.  Springer, Berlin, Germany. 
  • Yantasee W, Y Lin, K Hongsirikarn, GE Fryxell, S Addleman, and C Timchalk. 2000. "Electrochemical Sensors for the Detection and Quantification of Lead and Other Toxic Heavy Metals: The Next Generation of Personal Exposure Biomonitors." Environmental Health Perspectives 115(12):1683-1690. 


  • Lin Y, R Zhao, KD Thrall, C Timchalk, WD Bennett, and DW Matson. 1999. "Integration of Microfluidics/Electrochemical System for Trace Metal Analysis by Stripping Voltammetry." In Proceedings of SPIE. Microfludic Devices and Systems II: September 20-21, 1999, Santa Clara, California, vol. 3877, ed. C.H. Ahn and A.B. Frazier, pp. 248-256.  SPIE , Bellingham, WA. 

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