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.

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

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

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

Full Bio

Teresa S. Bowers, Ph.D.

Advising Principal

Expertise

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

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

Full Bio

Joel M. Cohen, Sc.D., DABT

Principal

Expertise

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

Full Bio

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

Principal Scientist

Expertise

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

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

Full Bio

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

Principal

Expertise

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

Full Bio

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

Principal

Expertise

• Contaminant Fate & Transport
• Environmental Forensics
• NAPL
• Historical Operations & Waste Practices
• Environmental Cost Analysis
• Site Characterization and Remediation Strategy

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

Full Bio

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

Principal

Expertise

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

Full Bio

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

Principal

Expertise

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

Full Bio

Ari S. Lewis, M.S.

Principal

Expertise

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

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)

Full Bio

David E. Merrill, M.S.

Advising Principal

Expertise

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

Full Bio

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

Principal

Expertise

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

Full Bio

Robyn Prueitt, Ph.D., DABT

Principal Scientist

Expertise

• Molecular Biology & Toxicology
• Carcinogenesis
• Human Genetics
• Molecular Epidemiology

Full Bio

Kim Reynolds Reid

Principal Scientist

Expertise

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

Full Bio

Lorenz R. Rhomberg, Ph.D., ATS

Advising Principal

Expertise

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

Full Bio

Jeffrey T. Rominger, Ph.D.

Principal Scientist

Expertise

• Contaminant Fate & Transport
• Environmental Forensics
• Fluid Dynamics
• Numerical Modeling
• PCBs

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

Full Bio

Caroline B. Tuit, Ph.D.

Principal Scientist

Expertise

• Chemical Fate/Transport
• Rare Earth and Minor Metals
• Sediment Management
• Cost Allocation
• Chemistry/Forensics

Full Bio

Peter A. Valberg, Ph.D., ATS

Advising Principal

Expertise

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

Full Bio

Tim Verslycke, Ph.D.

Principal

Expertise

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

Full Bio

A. Dallas Wait, Ph.D.

Advising Principal

Expertise

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