Sue Erhardt

Sue Erhardt

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Assistant Professor and Director of IR-4 Laboratory
Department of Entomology



PhD - Michigan State University, Analytical Chemistry/Environmental Toxicology (1989)
BA - Earlham College, Biology/Chemistry (1981)

Web: North Central Region IR-4 Project


Susan brought to the North Central Region IR-4 (NCR IR-4) laboratory years of experience of successfully leading laboratories. She first led the development of the PTRL-West residue laboratory located in Hercules, California, before moving to DowElanco as an environmental chemist. There she successfully led projects examining the environmental fate of pesticides utilizing radiolabeled compounds. Such work included both the examination of kinetics of the reactions, as well as the identification and isolation of reaction products. From there, Susan became the technical leader for the residue method development group where she was able to use both her analytical and leadership abilities. Susan joined the Discovery Organization of DowElanco to become part of the Activity Delivery Center of Expertise, whose mission it was to determine why new chemistries worked or did not work based on metabolism or physical property characteristics. Susan developed a variety of assays to assess how material moved in the xylem of a plant as well as updated methodologies examining electron transport inhibition to help inform chemical synthesis. She then moved to Dow Chemical in Midland, Michigan, to become a member of the Environmental Chemistry group. There she became one of the original scientists involved in the development of alternative in vitro methodologies for the assessment of bioaccumulation in fish. The work of the group continues to develop in vitro assays as acceptable alternatives procedures for regulatory assessment by the Environmental Protection Agency (EPA) and other regulatory bodies in place of currently existing guidelines which remain resource intensive. Dr. Erhardt became laboratory director of the NCR IR-4 project on Jan. 3, 2010.

Current assignment: Research 100%

Program Description

As laboratory director for the NCR IR-4 project, I oversee the analysis of field samples of specialty crops collected as part of studies conducted by the larger overall project IR-4. We are a laboratory that operates under good laboratory practices (GLP), which requires thorough documentation of all activities. The laboratory conducts pesticide residue analysis at the part per billion level (ppb) on specialty crops utilizing high-end analytical instrumentation such as LC-MS/MS. In addition, I interface with the IR-4 headquarters located at Rutgers University to communicate project status, provide counsel to the study directors who oversee the projects and submit analytical summary reports. The laboratory currently has six full-time and three part-time staff responsible for sample analysis. More than 600 samples are handled on an annual basis from receipt to disposal. Our data is submitted to the EPA or Ag Canada to generate pesticide tolerances or MRLs on specific minor use crops so growers can use the pesticides to address pest problems. We are funded through the United States Department of Agriculture - National Institute of Food and Agriculture (USDA-NIFA).

More information is available at our website: North Central Region IR-4 Project.


  • Analytical Chemistry
  • Environmental Chemistry
  • Environmental Modeling
  • Risk Assessment
  • Pesticide Residue Analytical Techniques

Professional Experience

  • 2010-Present – Laboratory Director IR-4 Project, Michigan State University, responsible for the direction, reporting and supervision of the analyses of raw agricultural commodities in support of minor use pesticide registration.
  • 2004-2009 – Senior Environmental Research Specialist, Dow Chemical, responsible for testing of industrial chemicals for registration of use and consulting with internal clients on environmental issues.
  • 1998-2004 – Metabolism Chemist, Discovery, Dow AgroSciences, responsible for meeting rapid ADME needs of Discovery organization in the in assessment of potential new actives for pesticide applications. Responsibilities included working with internal clients to develop and execute experimental plan.
  • 1993-1998 – Technical Leader, Residue Method Development, Regulatory Labs, DowElanco, responsible for 12 personnel involved with residue method development, oversaw hiring, study scheduling, instrument purchases/capital requests.
  • 1991-1993 – Environmental Fate Chemist, DowElanco, responsible for method development, conduct and reporting of environmental fate studies on bioactive materials using primarily 14-C labeled materials.
  • 1988-1991 – Manager, Residue Chemistry, PTRL-West, responsible for hiring personnel, interfacing with clients, report preparation, SOP development, instrumentation purchases in a GLP environment.

Selected Publications

  • Escher B, Cowan-Ellsberry CE, Dyer S, Embry MR, Erhardt, S, Halder M Kwon JH, Johanning K, Oosterwijk MTT, Rutishauser S, Segner H and Nichols J. Protein and lipid binding parameters to extrapolate from the in-vitro liver S9 metabolic assay to in-vivo rainbow trout (Oncorhynchus mykiss) bioaccumulation potential of hydrophobic organic chemicals. 2011. Chemical Research in Toxicology. 24: 1134-1143
  • Johanning K, Hancock G, Escher B, Adekola A, Bernhard MJ, Cowan-Ellsberry CE, Domoradzki J, Dyer S, Eickhoff C, Embry M, Erhardt S, Fitzsimmons P, Halder M, Hill J, Holden D, Johnson R, Rutishauser S, Segner H, Schultz I, and Nichols J. 2012. Assessment of Metabolic Stability Using the Rainbow Trout (Oncorhynchus mykiss) Liver S9 Fraction. Current Protocols Toxicology (In Review)
  • Anne V. Weisbrod, Jasminder Sahi, Helmut Segner, Margaret O. James, John Nichols, Irvin Schultz, Susan Erhardt, Christina Cowan-Ellsberry, Mark Bonnell, and Birgit Hoeger, 2009. The State of in Vitro Science for Use in Bioaccumulation Assessment for Fish, Environmental Toxicology and Chemistry 28:86–96.
  • Nichols, J, Susan Erhardt, Scott Dyer, Margaret James, Margo Moore, Kathleen Plotzke, Helmut Segner, Irvin Schultz, Karluss Thomas, Luba Vasiluk, Annie Weisbrod. Workshop Report: Use of In Vitro Absorption, Distribution, Metabolism, and Excretion (ADME) Data in Bioaccumulation Assessments for Fish. HERA (2007) in press.
  • Cowan-Ellsberry, C. E., Dyer, S. D., Erhardt, S., Bernhard, M. J. , Roe, A., Dowty, M. E. and Weisbrod, A. V. 2007. Approach for Extrapolating in vitro metabolism data to refine bioconcentration factor estimates. Chemosphere (2008), 70(10), 1804-1817.
  • Weisbrod, Annie; Bonnell, Mark; Dowty, Martin; Dyer, Scott; Erhardt, Sue; Escher, Beate; Nichols, John; Traas, Theo; Parkerton, Tom; Woodburn, Kent. The big picture: new concepts and method development for bioaccumulation assessment. Preprints of Extended Abstracts presented at the ACS National Meeting, American Chemical Society, Division of Environmental Chemistry (2006), 46(2), 789-792.
  • Cryer, Steven A.; Mann, Richard K.; Erhardt-Zabik, Susan; Keeney, F. Nelson; Handy, Paul R. Designing herbicide formulation characteristics to maximize efficacy and minimize rice injury in paddy environments. Pest Management Science (2001), 57(6), 479-490.
  • Erhardt-Zabik, Susan; Wolt, Jeff D. Design and interpretation of herbicide anaerobic aquatic metabolism studies.Weed Technology (1996), 10(1), 191-201.
  • Haven, P. L, Sims, G., K., Erhardt-Zabik, S. Fate of Herbicides in the Environment, in Handbook of Weed Management Systems, Edited by A. E. Smith. (1995), 245-278, Marcel Dekker, Inc., New York, New York.
  • Erhardt-Zabik, S.; Watson, J. T.; Zabik, M. J. Selective sensitivity of highly chlorinated species in negative ion mass spectrometry: implications for complex mixture analysis. Biomedical & Environmental Mass Spectrometry (1990), 19(3), 101-8.