Gradient

Principals

Gradient's Principals are nationally recognized experts and active contributors to the promotion of sound science. We maintain our position as leaders in our scientific specialties through professional certifications, peer-recognized publishing, panel and conference participation, continuing education, and hands-on work on some of the world's most challenging environmental issues.

Barbara D. Beck, Ph.D., DABT, ATS

Principal

Expertise

  • Inhalation Toxicology
  • Metals Toxicology
  • Historical Understanding of Toxicology
  • Regulatory Comment
  • Risk Communication

Leslie A. Beyer, M.S., DABT

Principal Scientist

Expertise

  • Occupational Health
  • Solvents
  • Historical Toxicology
  • Risk Assessment
  • Toxicology
  • Epidemiology
  • Toxic Tort Litigation Support

Andrew B. Bittner, M.Eng., P.E.

Principal Scientist

Expertise

  • NAPL Transport
  • Groundwater & Surface Water Modeling
  • Groundwater Hydrology
  • Soil Vapor Intrusion Modeling
  • Hydraulic/WWTP Modeling

Teresa S. Bowers, Ph.D.

Principal

Expertise

  • Statistical Methods
  • Geochemical Modeling
  • Exposure Modeling
  • Blood Lead Modeling
  • Lead, Arsenic, & PCBs
  • Cleanup Levels
  • Risk Communication

Catherine Petito Boyce, S.M.

Principal Scientist

Expertise

  • Exposure Modeling
  • Toxicity Assessment
  • Regulatory Comment
  • Cleanup Negotiations
  • Probabilistic Methods
  • Risk Assessment

Eric L. Butler, Ph.D.

Principal

Expertise

  • Environmental Forensics
  • Chemical Fingerprinting
  • Analytical Methods
  • Source Allocation
  • TPH, PAH, PCBs, Dioxins, Solvents, & Metals
  • Contemporary Archeology

Samuel A. Flewelling, Ph.D.

Principal Scientist

Expertise

  • Contaminant Fate & Transport
  • Hydraulic Fracturing
  • Hydrological Modeling
  • Chlorinated Solvents
  • NAPL
  • Metals
  • Induced Seismicity
  • Water Rights
  • Nutrients
  • Trace Metals
  • Petroleum Hydrocarbons

Julie E. Goodman, Ph.D., DABT, FACE, ATS

Principal

Expertise

  • Epidemiology
  • Toxicology
  • Risk Assessment
  • Product Safety
  • Carcinogenesis

Kurt Herman, M.Eng., P.G.

Principal

Expertise

  • Contaminant Fate & Transport
  • Environmental Forensics
  • NAPL
  • MGP and Wood Treating Sites
  • Historical Operations & Waste Practices
  • Environmental Cost Analysis

David E. Langseth, Sc.D, P.E., D.WRE

Principal

Expertise

  • Surface & Groundwater Hydrology
  • Water Quality Evaluation
  • Environmental Liability Evaluation

Tom A. Lewandowski, Ph.D., DABT, ERT, ATS

Principal

Expertise

  • Product Safety
  • Metals Toxicology
  • Pharmacokinetic Modeling
  • Risk Assessment
  • Alternative Assessment
  • Developmental Toxicology

Ari S. Lewis, M.S.

Principal

Expertise

  • Metals Toxicology
  • Molecular Toxicology
  • Human Health Risk Assessment
  • Arsenic Toxicology

Christopher M. Long, Sc.D., DABT

Principal Scientist

Expertise

  • Indoor/Outdoor Air Pollution
  • Air Sampling, Measurement, & Modeling
  • Exposure Assessment
  • Inhalation Risk Assessment
  • Electric and Magnetic Fields (EMF)

David E. Merrill, M.S.

Principal

Expertise

  • Risk-based Cleanup Negotiations
  • PCBs & Sediments
  • Multimedia Modeling
  • Statistical & Monte Carlo Methods
  • Database Design & Synthesis

Kim Reynolds Reid

Principal Scientist

Expertise

  • Environmental Chemistry
  • Sampling & Analysis Design
  • Inorganic/Organic Data Interpretation
  • Project Management
  • Quality Assurance Oversight

Lorenz R. Rhomberg, Ph.D., ATS

Principal

Expertise

  • Weighing Toxicologic Evidence
  • Quantitative Risk Methods
  • Pharmacokinetic Modeling
  • Chlorinated Solvents
  • Risk Policy & Methodology
  • Cumulative Risk

Manu Sharma, M.S., P.E.

President

Expertise

  • Contaminant Fate & Transport
  • Environmental Forensics
  • Hydraulic Fracturing
  • Risk-based Remediation
  • Cost Allocation/Liability Assessment
  • Water Resources

Peter A. Valberg, Ph.D., ATS

Principal

Expertise

  • Risk Communication
  • Inhalation Toxicology
  • Exposure Modeling
  • Airborne Pollutants & Particulates
  • Radiation & Radionuclide Risk
  • Electromagnetic Fields

Tim Verslycke, Ph.D.

Principal

Expertise

  • Environmental Risk Assessment
  • Standard & Regulatory Chemical Screening & Testing
  • Endocrine Disruptors
  • Pharmaceuticals in the Environment
  • Product Safety

A. Dallas Wait, Ph.D.

Principal

Expertise

  • Consumer Product Characterization
  • Natural Product Chemistry
  • Environmental Chemistry & Forensics
  • Test Method Evaluation & Design
  • Historical Analytical Chemistry Practices
  • Data Quality