Dr. Johnson currently serves as the Director of Toxicology, US Army Public Health Center at Aberdeen Proving Ground, MD where he is responsible for the operational and technical arm of the Army Surgeon General and the Assistant Secretary of the Army for toxicological matters. He has worked extensively in the evaluation of the toxicity of military unique compounds and development and evaluation of a phased approach to the gathering toxicity data for new compounds under development. He has authored over 100 peer-reviewed publications, book chapters, and technical reports and serves on several NATO and EPA panels. He has been a member of Society of Environmental Toxicology and Chemistry (SETAC) since 1997 and currently serves on the Board of Directors for SETAC North America. He is the past chair of Ecological Risk Assessment World Interest Group, and a member of the World Science Committee for SETAC
and SETAC North America. Dr. Johnson is also a member of the International Board of Environmental Risk Assessors (IBERA). He has been a member of the Society of Toxicology since 2009.
Dr. Johnson is a Fellow of the Academy of Toxicological Sciences, Chair of the Tri-Service Toxicology Consortium (TSTC), past Steering Committee Chair of the Joint Army-Navy-NASA-Air Force (JANNAF) Subcommittee on Safety and Environmental Protection, and Past-President of the American Board of Toxicology (ABT).