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Our Team

Michael Dourson

Michael L. Dourson, PhD, DABT, FATS, FSRA

President:

Dr. Michael Dourson is a board-certified toxicologist serving as TERA’s President and Director of Science. Most recently, he was Senior Advisor in the Office of the Administrator at the US EPA. Prior to this position, Dr. Dourson was a Professor in the Risk Science Center at the University of Cincinnati, College of Medicine and worked at TERA and US EPA. He was awarded the Arnold J. Lehman award from the Society of Toxicology, the International Achievement Award by the International Society of Regulatory Toxicology and Pharmacology, and 4 bronze medals from the U.S. Environmental Protection Agency. He has been elected as a Fellow of the Academy of Toxicological Sciences and as a Fellow for the Society for Risk Analysis. He has co-published more than 150 papers on risk assessment methods or chemical-specific analyses, and co-authored hundreds of government risk assessment documents, many of them risk assessment guidance texts. He has made over 150 invited presentations to a variety of organizations, and has chaired over 150 sessions at scientific meetings and independent peer reviews. He has been elected to multiple officer positions in the American Board of Toxicology (including its President), the Society of Toxicology (including the President of 3 specialty sections), the Society for Risk Analysis (including its Secretary), and President of the Toxicology Education Foundation, a nonprofit organization with a vision to help the public understand the essentials of toxicology. In addition to numerous appointments on government panels, such as EPA’s Science Advisory Board, he is a current member on the editorial board of Regulatory Toxicology and Pharmacology..

Bernard Gadagbui

Bernard K. Gadagbui, M.S., Ph.D., DABT, ERT

Vice President, Toxicology Excellence for Risk Assessment (TERA)

Executive Leader in Human Health Risk Assessment, Regulatory Toxicology, and Regulatory Science

Transforming Toxicological Science into Public Health Protection—and Developing the Next Generation of Scientific Leaders.

Dr. Bernard K. Gadagbui is a board-certified toxicologist (Diplomate of the American Board of Toxicology, DABT) and European Registered Toxicologist (ERT) with more than 25 years of international experience in regulatory toxicology, human health risk assessment, dose-response assessment, occupational toxicology, and regulatory science.

As Vice President of Toxicology Excellence for Risk Assessment (TERA), he provides executive scientific leadership for multidisciplinary programs supporting government agencies, multinational corporations, nonprofit organizations, and international organizations in addressing complex public health, environmental, pharmaceutical, and occupational health challenges. He also directs TERA’s internationally recognized Dose-Response Assessment Training Program, mentoring scientists and advancing excellence in evidence-based risk assessment.

Dr. Gadagbui’s expertise spans hazard identification, dose-response assessment, benchmark dose modeling, weight-of-evidence evaluation, exposure assessment, occupational exposure limits, health-based guidance values, pharmaceutical and medical device safety, and regulatory decision-making. His work has contributed to scientifically robust approaches for protecting workers, consumers, and the public.

A recognized educator and mentor, Dr. Gadagbui has trained toxicologists, risk assessors, regulators, and public health professionals from government, academia, industry, and consulting organizations around the world. His leadership in professional societies and scientific training reflects his enduring commitment to strengthening the global practice of regulatory science.

Dr. Gadagbui earned a B.Sc. (Hons.) in Biochemistry with Chemistry from the University of Ghana, followed by an M.S. in Biochemistry and a Ph.D. in Environmental Health from the University of Bergen, Norway. He is a Diplomate of the American Board of Toxicology (DABT) and a European Registered Toxicologist (ERT). His professional mission is to protect human health through sound science while developing the next generation of human health and environmental risk assessors through scientific excellence, education, mentorship, and international collaboration.

Chijioke Onyema

Chijioke Onyema, M.Sc., MPH

Toxicologist:

Chijioke Onyema is a Medical Microbiologist and Master of Public Health (MPH) graduate who hails from Lagos, Nigeria. His interest in human health was spurred by personal experience, having had a fair share of illnesses in his childhood (jaundice, pneumonia, and malaria, to mention a few). An internship at the Nigerian Institute of Medical Research (NIMR), an award for the second-best graduating student in his undergraduate class, and a master’s degree in Medical Microbiology from the University of Lagos, Nigeria only served to further fuel his quest for knowledge.

Having joined the Toxicology Excellence for Risk Assessment (TERA) in 2016 while pursuing his MPH degree at the University of Cincinnati, Chijioke is presently particularly interested in toxicological evaluations and risk/exposure assessments and has co-authored a few exposure assessment reports. He currently works as a Toxicologist with TERA and is a member of the renowned Society of Toxicology (SOT).

Valerie Ayers

Valerie Ayers

Executive Office Administrator:

Ms. Ayers joined TERA in 2006. She brings with her a wealth of administrative experience.

Christen Williams, MTSC, MCSE, CISSP, CCENT

IT & New Technology Manager:

Ms. Christen Williams is TERA’s IT Services and New Technology Manager. Ms. Williams has worked with TERA since 2010 and has 29 years of experience in graphic design, computer support, networking and design, server support, cloud computing, and cyber and network security. She is certified as Moxa Technical Support Certification, Microsoft Certified Systems Engineer, Certified Information Systems Security Professional, and Cisco Certified Entry Networking Technician.

Bethany Hanson

Bethany D. Hansen, M.A.

Communications Specialist:

Mrs. Hansen recently joined TERA as the Communications Specialist, and is leading TERA’s social media, public outreach, and public toxicology education. Mrs. Hansen earned her M.A. in Communications from Northern Kentucky University.  She has 6 years of experience in Communications through her former role as Executive Assistant at Cincinnati State Technical and Community College. 

Corporate Info

Resources

Our Brands

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Contacts

  • 1250 Ohio Pike, Suite 197, Cincinnati Ohio 45102
  • 513.488.1990
  • TERA@TERA.ORG

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WEEL OEL

Occupational Exposure Limits (OELs) are designed to safeguard the health of healthy workers during their careers. These limits are based on the assumption of repeated daily exposure throughout a working lifetime, typically averaged over an 8-hour workday. Their purpose is to prevent both immediate (acute) and long-term (chronic) health issues arising from workplace exposures. It’s important to note that OELs are not intended for the general public, which includes vulnerable groups like infants, the elderly, and those with pre-existing health conditions.

Workplace Environmental Exposure Levels (WEELs) are health-based guidelines for chemical hazards in the workplace. These values represent air concentrations believed to protect the majority of workers from negative health effects resulting from occupational chemical exposure.

The WEEL Process
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The development of new or revision of existing WEELs is typically assigned to voluntarily designated subcommittees. A subcommittee usually comprises 3 – 4 members from the WEEL Committee. New WEELs are developed using the OARS-WEEL administrative standard operating procedure (SOP), while existing WEELs are usually revised every 10 years, unless the availability of significant new data which may impact the existing WEEL value compels the committee to make a revision sooner. The OARS-WEEL SOP contains procedures and guidelines governing conflicts of interest, draft document preparation, literature searches, draft document review, balloting process, post-ballot WEEL documentation quality assurance scientific review, and publication.

Once a subcommittee has prepared a draft WEEL document, a review of the draft is scheduled for the next available Committee meeting. The WEEL Committee members are expected to have reviewed all such drafts prior to the meeting. If no major changes are necessary to a draft, the attending Committee membership may, by a simple majority, approve the WEEL for balloting. Alternatively, the Committee may direct the subcommittee to revise the WEEL and present it for further discussion at a future meeting. If a ballot is not approved by a two-thirds majority of non-abstaining Committee members, it is discussed at the next Committee meeting to determine the appropriate course of action. Once the WEEL is approved by a two-thirds majority of non-abstaining Committee members, copies of ballot comments are forwarded to the designated subcommittee and all substantive comments must be addressed in the final draft. If resolution of a substantive comment results in a change to the WEEL value or a change in the basis for the value, the draft must be re-balloted.

Once all comments have been addressed on a successfully balloted draft, document formatting and editorial review are performed by TERA, before the draft WEEL document is made available for public comment (usually for a period of 30 days but may be extended if the need arises). After the public comment period has elapsed, comments are addressed by the subcommittee responsible for that specific draft, after which the WEEL documentation is submitted to Toxicology and Industrial Health (TIH), a peer-reviewed medical journal that covers research in the fields of occupational health and toxicology, for publication. A thorough review of the galley proof by the scientific content quality coordinator at TERA, and proofreaders and editors at TIH is the penultimate step before eventual publication of the WEEL documentation.

The WEEL Committee

The OARS-WEEL Committee is composed of volunteer experts specializing in the scientific determination of occupational exposure levels. This committee actively seeks a balanced representation of professionals from toxicology and industrial hygiene, drawing upon a diverse range of experience from industry, government, academia, and consulting. Importantly, each member contributes to the Committee based on their individual expertise and not as an official representative of their respective employer, organization, or agency.