Dr. Thiessen is experienced in the evaluation of exposures, doses, and risks to human health from trace levels of contaminants in the environment and in the use of uncertainty analysis for environmental and health risk assessment.  She recently led the Urban Environments Working Group of the International Atomic Energy Agency's MODARIA (Modelling and Data for Radiological Impact Assessments) program.  Prior to the MODARIA program, she led the Urban Remediation and Urban Areas Working Groups within the IAEA's EMRAS (Environmental Modelling for Radiation Safety) and EMRAS II programs and the Dose Reconstruction Working Group of the IAEA’s BIOMASS (Biosphere Modelling and Assessment Methods) program.  She served as a member of the 

Coordinating Committee for the​ MODARIA, EMRAS, EMRAS II, and BIOMASS programs.  She also serves on a committee for the revision of the International Atomic Energy Agency's Safety Report Series No. 19, "Generic Models for Use in Assessing the Impact of Discharges of Radioactive Substances to the Environment," and is involved in the preparation of an IAEA guidance document on implementation of remediation strategies following accidental releases of radioactivity.  Dr. Thiessen recently participated in two symposia on reconstruction of internal doses from Fukushima releases organized by Japan's National Institute of Radiological Sciences, and she has served as a consultant on environmental modeling issues to the Korea Atomic Energy Research Institute.  Dr. Thiessen has served on two National Research Council subcommittees, one dealing with guidance levels for air contaminants in submarines and one charged with the review of fluoride exposure and toxicology.  Dr. Thiessen has drafted several reports on the health effects of specific environmental contaminants for the U.S. Environmental Protection Agency.  Dr. Thiessen has also co-authored several papers on contaminant interception and retention by vegetation and assisted with a review paper on this topic prepared for the International Atomic Energy Agency.  She contributed to the development of a risk-based screening approach to prioritize further investigation of contaminants and exposure situations in various assessment contexts.  For the State of Tennessee, Dr. Thiessen led an analysis of human exposures, doses, and health risks to off-site individuals associated with historic releases of radionuclides to the Clinch River from DOE’s Oak Ridge facilities.  She also led in the application of risk-based screening techniques for the reconstruction of doses and health risks associated with releases of chemicals and radionuclides from the Oak Ridge facilities. She served as a consultant to the National Council on Radiation Protection and Measurements for the preparation of "A Guide for Uncertainty Analysis in Dose and Risk Assessments Related to Environmental Contamination" (NCRP Commentary No. 14, 1996).  Dr. Thiessen has contributed to a number of open literature publications in the use of international data sets to test and improve the accuracy of mathematical models used to assess the environmental fate and consequences of releases of radioactivity.

E-mail Dr. Thiessen at: kmt@orrisk.com

Kathleen M. Thiessen, Ph.D.


Senior Scientist