G Craig Llewellyn, PhD
Principal and Scientific Director

Andrey I Nikiforov, PhD
Senior Scientific Advisor

Keith A Hostetler, PhD
Senior Managing Toxicologist

Louan C Fisher, RQAP-GLP
Senior Managing Consultant
QA and Scientific Affairs

Marisa O Rihner, RQAP-GLP
Senior Managing Consultant
QA and Regulatory Affairs

Benjamin L Burruss, RQAP-GLP
Senior Consultant

Julia Parker
Senior Consultant

Sari L Weston
Senior Consultant

Dotti S Bradshaw
Executive Assistant


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Professional Staff

TRS professional toxicologists are highly qualified, experienced, specialists who offer a wealth of experience in designing, monitoring, and evaluating toxicology, chemistry and environmental fate and effects data development programs as well as other scientific consulting services. TRS quality assurance professionals conduct GLP data and report audits and GLP facility inspections and have a combined 50 years of auditing experience.

TRS staff are dedicated professionals committed to providing the highest quality consulting services at a reasonable cost to our clients.


Please click on the links at left for a brief biography and a link to the curriculm vitae of each staff member. A printable brochure containing the biographies of our scientific staff also is available on our brochure page.