Jump to main content or area navigation.

Contact Us

Exposure Research

Human Exposure & Atmospheric Sciences Staff

Jeffre C. Johnson

Title: Research Chemist

EPA Division: Human Exposure and Atmospheric Sciences Division

EPA Branch: Exposure and Dose Research Branch

Jeffre’s expertise is in matching the emergent high performance computing needs of current and future pharmacokinetic modeling studies within HEASD/EDRB with the development of the necessary higher throughput algorithms. In particular, linkage of stochastic exposure models with PBPK models, an emergent are, will tax current PBPK modeling systems beyond the limits of computational tractability.

Thus, Jeffre is developing PBPK models for high performance computing (HPC) environments, with end targets being parallelized, high throughput PBPK models.

Jeffre has extensive expertise in PBPK modeling within the framework of the exposure related dose estimating model (ERDEM) in particular with regard to n-methyl carbamate cumulative risk assessment for carbaryl, aldicarb, and carbofuran.


  • M.S., Chemistry, University of Illinois at Urbana-Champaign, 1987
  • B.S., Chemistry, University of Wisconsin-Madison, 1982
  • Graduate level studies in computer science, Algorithmics, UNLV dept of Computer Science

Professional Experience:

  • Research Chemist, USEPA, NERL, 1991-present
  • Chemist, USDA, ARS, WHNRC, 1988-1991
  • Chemist, Tucson Water, 1987

Professional Societies and Affiliations:

  • American Chemical Society

Select Awards and Honors:

  • USEPA, Exceptional/Outstanding ORD Technical Assistance to the Regions or Program Offices, 2007

Select Presentations:

  • Zhang, X., Okino, M.S., Knaak, J.B., Tsang, A.M., Power, F.W., Xue, J., Harrison, L.S., Gerlach, R.W., Heravi, N.E., Johnson, J.C., Dary, C.C, A Physiologically Based Pharmacokinetic/Pharmacodynamic (PBPK/PD) Model for Estimation of Cumulative Risk from Exposure to Three N-Methyl Carbamates: Carbaryl, Aldicarb, and Carbofuran , 46th Annual Society of Toxicology Meeting, Charlotte, NC, March 25—29, 2007.
  • D. T. Chang, M.S.Okino, R. Tornero-Velez, J. B. Knaak, K. Enslein, F.W. Power, J. C. Johnson, C. S. Mazur, J. F. Kenneke, M. E. Dellarco, T. Collette and C. C. Dary, Suitability of Using QSAR to Generate Computationally Estimated Parameters in PBPK/PD Models, International Science Forum on Computational Toxicology, Research Triangle Park, NC, May 2007
  • D. T. Chang, T. L. Whitehead, M. S. Okino, J. F. Kenneke, C. S. Mazur, R. Tornero-Velez, J. Johnson and C. C. Dary, An In Silico Investigation of the Enantioselective Metabolism Rates of Triazole Fungicides, 14th Annual North American International Society for the Study of Xenobiotics Meeting, Rio Grande, Puerto Rico, October 2006
  • Johnson, J. C., Van Emon, J. M., Chuang, J. C. Quantitative ELISA of Polychlorinated Biphenyls in an Oily Soil Matrix Poster presented at Immunochemistry Summit VII & Third Workshop on Biosensors and Biological Techniques in Environmental Analysis, Las Vegas, NV, December 1-3, 1998.
  • Johnson, J. C., Van Emon, J. M., Chuang, J. C., Clarke, A. N., Wamsley, B. M., Reevaluation of Polychlorinated Biphenyl Contaminated Gencorp Lawrence Soil Using Quantitative Immunoassay presented at the 214th American Chemical Society National Meeting, Las Vegas, NV, September 7-11, 1997.
  • Johnson J. C., Van Emon, J. M., Immunoassay Test Kits in Environmental Monitoring presented at the 111th AOAC International Annual Meeting, San Diego, CA, September 7-11, 1997.

Select Publications:

  • Johnson, J. C., Van Emon, J. M., Clarke, A. N., Wamsley, B. N. Quantitative ELISA of Polychlorinated Biphenyls in an Oily Soil Matrix Using Supercritical Fluid Extraction, Analytica Chimica Acta, 428(2), 191-199, 2001.
  • Van Emon, J. M., Gerlach, C. L., Johnson, J. C., Immunoassay Test Kits in Environmental Monitoring in Current Issues in Regulatory Chemistry, pp. 135-150, AOAC International, Gaithersburg, MD, 2000.
  • Chuang, J. C., Miller, L. S., Davis, D. B., Peven, C. S., Johnson, J. C., Van Emon, J. M. Analysis of Soil and Dust Samples for Polychlorinated Biphenyls by Enzyme-linked Immunosorbent Assay (ELISA), Analytica Chimica Acta, 376(1): 67-75, 1998.
  • Johnson, J. C., Van Emon, J. M., Pullman, D. R., Keeper, K. R. Development and Evaluation of Antisera for Detection of the O,O-Diethyl Phosphorothionate and Phosphorothionothiolate Organophosphorous Pesticides by Immunoassay Journal of Agricultural and Food Chemistry, 46(8): 3116-3123, 1998.
  • Johnson, J. C., Van Emon, J. M. Quantitative Enzyme-linked Immunosorbent Assay for Determination of Polychlorinated Biphenyls in Environmental Soil and Sediment Samples Analytical Chemistry, 68(1): 162-169, 1996.
  • Johnson, J. C., Van Emon, J. M. Development and Evaluation of a Quantitative Enzyme Linked Immunosorbent Assay (ELISA) for Polychlorinated Biphenyls EPA/600/R-94/113, June 1994.

Published & Presented Research (1999-Present)

Contact Info:
Jeffre C. Johnson
Human Exposure & Atmospheric Sciences Division
National Exposure Research Laboratory
US EPA Office of Research and Development
944 East Harmon Avenue
Las Vegas, NV 89119
Telephone: 702-798-2177
Email: johnson.jeffre@epa.gov

Jump to main content.