Gradient

Principals

Gradient's Principals are nationally recognized experts and active contributors to the promotion of sound science 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.

Lisa A. Bailey, Ph.D. Full Bio

Lisa A. Bailey, Ph.D.

Principal Scientist

Expertise

  • Molecular Biology & Toxicology
  • Carcinogenesis
  • Mode-of-action Analyses
  • Human Exposure
  • Risk Assessment
  • DNA Damage, Repair and Mutagenesis
  • Weight of Evidence

Barbara D. Beck, Ph.D., DABT, ATS, AAAS Fellow Full Bio

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

Principal

Expertise

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

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

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

Principal

Expertise

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

Teresa S. Bowers, Ph.D. Full Bio

Teresa S. Bowers, Ph.D.

Principal

Expertise

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

Eric L. Butler, Ph.D. Full Bio

Eric L. Butler, Ph.D.

Principal

Expertise

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

Joel M. Cohen, Sc.D., DABT Full Bio

Joel M. Cohen, Sc.D., DABT

Principal Scientist

Expertise

  • Inhalation Toxicology
  • Alternative Assessment
  • Nanotechnology
  • Skin Sensitization
  • Proposition 65
  • Medical Device Biocompatibility
  • Extractables and Leachables
  • Pharmaceutical Non-Clinical Safety
  • Consumer Product Safety

David G. Dodge, M.S., DABT, CIH Full Bio

David G. Dodge, M.S., DABT, CIH

Principal Scientist

Expertise

  • Risk Communication
  • Human Health Risk Assessment
  • Industrial Hygiene
  • Historical State-of-Knowledge

Samuel A. Flewelling, Ph.D. Full Bio

Samuel A. Flewelling, Ph.D.

Principal

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 Full Bio

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

Principal

Expertise

  • Epidemiology
  • Toxicology
  • Exposure
  • Risk Assessment
  • Systematic Review
  • Product Safety

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

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

Jessie M. Kneeland, Ph.D. Full Bio

Jessie M. Kneeland, Ph.D.

Principal Scientist

Expertise

  • Chemical Fingerprinting
  • Organic Geochemistry
  • Oceanography
  • Climate Change Science
  • Environmental Forensics
  • Fate and Transport
  • Product Stewardship

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

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 Full Bio

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. Full Bio

Ari S. Lewis, M.S.

Principal

Expertise

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

Christopher M. Long, Sc.D., DABT Full Bio

Christopher M. Long, Sc.D., DABT

Principal

Expertise

  • Inhalation Toxicology
  • Human Health Risk Assessment
  • Exposure Assessment
  • Indoor/Outdoor Air Quality
  • Electric and Magnetic Fields (EMF)

David E. Merrill, M.S. Full Bio

David E. Merrill, M.S.

Principal

Expertise

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

Michael K. Peterson, M.E.M., DABT Full Bio

Michael K. Peterson, M.E.M., DABT

Principal

Expertise

  • Occupational Health
  • Product Safety
  • Human Health Risk Assessment
  • Applied Toxicology

Kim Reynolds Reid Full Bio

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 Full Bio

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. Full Bio

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

President

Expertise

  • Contaminant Fate & Transport
  • Environmental Forensics
  • Risk-based Remediation
  • Water Resources
  • Remedy Reasonableness
  • Cost Recovery/Allocation

Peter A. Valberg, Ph.D., ATS Full Bio

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. Full Bio

Tim Verslycke, Ph.D.

Principal

Expertise

  • Natural Resource Damage Assessment
  • Product Environmental Safety Assessment
  • Emerging Contaminants
  • Ecotoxicology and Ecological Risk Assessment

A. Dallas Wait, Ph.D. Full Bio

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