SC 1-25: Recent Epidemiologic Studies and Implications for the Linear-Nonthreshold Model

Members only

SC 1-25 will prepare a commentary reviewing recent epidemiologic studies and evaluate whether the new observations are strong enough to support or modify the linear nonthreshold (LNT) model as used in radiation protection today. The major recent studies, within the past 5 y, will be reviewed and strengths and limitations discussed, similar to the recent UNSCEAR (2013) annex coverage of childhood exposures to computed tomography (CT) exams and risks. While a comprehensive evaluation of LNT is not feasible within the 15 month time frame, the Committee will address briefly current understanding of new radiation biology. The commentary will be in support of the ongoing CC 1 report, Radiation Protection Guidance for the United States.

On December 8, 2015, the Co-Chairs, Staff Consultant, and NCRP President held a conference call to plan next steps. The first committee meeting was held December 17–18, 2015. The Committee discussed the rationale for the commentary and the intent of the commentary to inform CC 1 on the impact of recent epidemiological studies on the LNT model used to describe human response to radiation exposure. It was agreed that the commentary will not include a review of all literature but will include recent (within approximately 5 y) epidemiological studies that had been studied extensively and included adequate dosimetry. Ecological studies will not be included. A preliminary outline of the commentary was developed as follows:

  • Introduction
  • Epidemiological Studies
    • Cancer studies initially identified: atomic bomb, Chernobyl, CT exams, INWORKS, 15 Country Study (summary), Mayak, other worker studies, nuclear weapons (Atomic Veterans), Techa River, U.S. radiologic technologists, Million Person Study, high natural background, Taiwan.
    • Cardiac/circulatory: Atomic bomb survivor Studies, TB/Fluoroscopy Studies, Other Worker Studies.
  • Integration of New Findings
    • genetics, children, prenatal, noncancer effects (hypothyroidism)
  • Implications of findings for radiation protection and protective implementation
  • Improved communication to broader audiences

Writing assignments were made with a goal of each author having one writing assignment completed or one epidemiological study analyzed and written up by January 31, 2016 and posted to the Committee’s SharePoint site. Major epidemiological studies were identified and assigned primary and secondary reviewers. Potential expert reviewers were identified to review the completed commentary. The next meeting of the Committee will be by teleconference supported by WebEx on February 29, 2016.

SC 1-25 met via teleconference on February 29, 2016. It was reported that representatives of the U.S. Nuclear Regulatory Commission (NRC) had reiterated their interest in the commentary and were hopeful it could be completed by end of 2016, if possible. The Committee discussed progress to date and the need to keep the commentary short. A considerable amount of dosimetry information had been collected, and the Committee discussed how to best utilize this information. Following the conference call, a project planner was created to track the time goals of the Committee and the progress of authors.

A second teleconference was held on March 28 to review progress. Linda Walsh was added to the Committee membership to help with statistics. It was reported that representatives of the Government Accounting Office had expressed an interest in costs associated with use of linear nonthreshold (LNT) to establish radiation protection guidelines and regulations. They were keen on receiving a copy of the completed report by the end of 2016, if possible. With the amount of literature that needs to be reviewed and summarized, the Committee did not think it would be possible to complete the report before the original target date of March 31, 2017. Based on literature reviewed to date, the proposed table of contents was revised slightly and authors assigned to new sections. The Committee discussed plans to meet opportunistically in conjunction with the NCRP Annual Meeting.

NCRP is grateful to the U.S. Nuclear Regulatory Commission for financial support of this work.

The membership of SC 1-25 is:


was a Professor and Chief of the Epidemiology Division at New York University School of Medicine before going to the Radiation Effects Research Foundation (RERF) in Hiroshima-Nagasaki as Vice Chairman and Chief of Research. He is an author of ~100 radiation-related publications and is currently working with other RERF investigators on studies of radiation and various diseases.

He has served on numerous governmental and scholarly committees, including as a long-time member of the International Commission on Radiological Protection and NCRP, and has served on various committees or task groups for the United Nations Scientfic Committee on the Effects of Atomic Radiation, the World Health Organization, the National Academy of Sciences, the National Cancer Institute, and the U.S. Environmental Protection Agency, among others. His interests include the effects of radiation on both cancer and noncancer disease incidence, and understanding the epidemiologic and biological modification of radiation effects by various environmental, genetic and age factors.

roy e. shore, Chairman
Dr. Lawrence Dauer 


is Associate Attending Physicist, and Associate Clinical Member in the Departments of Medical Physics and Radiology at Memorial Sloan-Kettering Cancer Center (MSKCC) in New York City. He earned an MS in Health Physics and a PhD in Adult Education. He is certified in comprehensive health physics by the American Board of Health Physics and is past chair of the Radiation Safety Committee of the American Association of Physicists in Medicine (AAPM), past President of the Greater New York Chapter of the Health Physics Society (HPS), Executive Council Member of the Medical Physics Section of the HPS, a Member of the Joint Safety Committee of the Society for Interventional Radiology and the American College of Radiology, past council member of the Radiological and Medical Physics chapter of the AAPM, and a member of editorial and review boards of several scientific journals. He serves as the Chair of the MSKCC Emergency Management Committee, a member of the Radiation Injury Treatment Network. In 2005, he received the Elda E. Anderson Award from HPS. He is a Council member and serves on he Board of Directors of the NCRP. He also serves as a member of the International Commission on Radiological Protection Committee 3 on protection in medicine, a member of the science council for the International Organization for Medical Physics, and was on the program committee for the International Atomic Energy Agency's International Conference on Radiation Protection in Medicine-Setting the Scene for the Next Decade. He serves on the Radiation Advisory Committee of the U.S. Environmental Protection Agency's Science Advisory Board. He has several publications in the topical areas of radiation protection and risks in the fields of detection, radiology, interventional radiology, x-ray imaging, nuclear medicine, and radiation oncology, as well as surgery and medicine.

lawrence t. dauer, Co-Chair
DavisS Scott Davis
Beck H


Beck H

was a physicist for the U.S. Department of Energy (DOE)/ERDA/Atomic Energy Commission for over 36 y. Mr. Beck retired in 1999 as the Director of the Environmental Science Division of the DOE Environmental Measurements Laboratory (EML) in New York City and is presently a self-employed consultant specializing in environmental radiation dose reconstructions. During his tenure at EML, he also served as Director of the EML Instrumentation Division, and as Acting Deputy Director of the Laboratory. Mr. Beck has authored well over 100 publications in the areas of radiation physics, radiation measurement, dose reconstruction, environmental radiation, and radiation dosimetry. He served as Scientific Vice President for Radiation Measurements and Dosimetry of NCRP from 1996 to 2003, and in 2004 was elected to Distinguished Emeritus membership in NCRP. From 2004 to 2006, he served as a member of the National Academy of Sciences, National Research Council (NAS/NRC) Board on Radiation Effects Research /Nuclear and Radiation Studies Board.

He currently serves as a member of the Veterans (federal advisory) Board on Dose Reconstruction and the U.S. Scientific Review Group, DOE Russian Health Studies Program. He has served as an expert member on a number of NCRP and NAS/NRC scientific studies related to radiation dosimetry and as Chair of two NCRP committees and one NCRP Program Committee. He is a member of the American Association for the Advancement of Science, the American Nuclear Society, and a Fellow of the Health Physics Society.

harold l. beck

Emily A. Caffrey

is President and owner of Radian Scientific, currently supporting Risk Assessment Corporation in independent environmental dose and risk assessments. She graduated in 2016 with her PhD in Radiation Health Physics from Oregon State University. Her research included environmental dose assessment and computational dosimetry methods. She has published several articles on radioprotection of the environment. In addition to consulting, she is also an adjunct faculty member at the University of Alabama at Birmingham, assisting them in starting a new graduate level health physics program and teaching Introduction to Health Physics, Principles of Dosimetry, Non-ionizing Radiation, and Advanced Radiation Biology. She is interested in statistical uncertainty analysis, data interpretation, risk assessment, and source term development.

Emily A. Caffrey



is President of Cascade Scientific, Inc., an environmental consulting firm. Dr. Grogan received her PhD from Imperial College of Science and Technology at the University of London in 1984 and has more than 25 y of experience in radioecology, environmental dose reconstruction, and the assessment of radioactive and nonradioactive hazardous wastes. She first worked at the Paul Scherrer Institute in Switzerland on the performance assessment of radioactive waste disposal for the Swiss National Cooperative for the Disposal of Radioactive Waste (Nagra). Dr. Grogan was actively involved in the early international cooperative efforts to test models designed to quantify the transfer and accumulation of radionuclides and other trace substances in the environment.

Validation of computer models developed to predict the fate and transport of radionuclides in the environment remains a key interest of hers. In 1989 Dr. Grogan returned to the United Kingdom as a senior consultant to Intera Information Technologies before moving to the United States a few years later, where she has worked closely with Risk Assessment Corporation managing the technical aspects of a wide variety of projects that tend to focus on public health risk from environmental exposure to chemicals and radionuclides. Dr. Grogan has served on committees for the National Academy of Sciences, the International Atomic Energy Agency, the U.S. Environment Protection Agency, and NCRP. She co-edited the text book Radiological Risk Assessment and Environmental Analysis published by Oxford University Press in July 2008, and authored the chapter on Model Validation.

helen a. grogan

Randall N. Hyer


Randall N. Hyer, Senior Fellow and Assistant Director for Environmental, Health and Safety, Center for Risk Communication.

Dr. Hyer graduated with distinction from the U.S. Naval Academy, and served 12 y on active duty in the U.S. Navy. After earning his medical degree from Duke University, Dr. Hyer served as the 40th Winter-Over Medical Officer and Assistant Officer-in-Charge with Operation DEEP FREEZE at McMurdo and South Pole Stations in Antarctica. Dr. Hyer earned his PhD from Oxford, studying the molecular genetics of juvenile diabetes and helped determine the role of the insulin gene in disease susceptibility.

In 1994, the National Institutes of Health awarded Dr. Hyer the "NIH Outstanding Research Award for Clinical Trainees." Trained in public health at Walter Reed Hospital and Harvard University, Commander Hyer supported four major military operations in the European, African, and southwest Asian theatres to include service as Chief Public Health Advisor for the Kosovo operations and Deputy Surgeon for the Mozambique flood relief operations. Dr. Hyer then spent 4 y at the World Health Organization (WHO) in Geneva as the first WHO Civil Military Liaison Officer and served as part of the WHO's outbreak response team to deadly outbreaks like anthrax, SARS, and avian influenza as well as having organized missions during the 2005 Tsunami response. His experiences with the media in outbreaks and emergencies led him to coauthor the popular WHO handbook, Effective Media Communication During Public Health Emergencies.

Appointed a U.S. Congressional Fellow for Senator Pete V. Domenici (R-New Mexico), he helped introduce legislation to safeguard genetic privacy that eventually became the Genetic Information Non-discrimination Act (GINA) of 2008. In 2005, Dr. Hyer joined Merck Vaccine Division in Global Medical Affairs and Policy. His focus has been the human papilloma virus (HPV) vaccine. In 2009, he was transferred to MSD in Tokyo, Japan.

Randall N. Hyer



is currently Professor Emeritus and Clinical Professor at the Department of Radiology at the University of New Mexico School of Medicine. He was chairman of the department for 18 y from 1994 to 2003. He is currently in the Radiology and Nuclear Medicine Service at the New Mexico Federal Regional Medical Center.

He graduated with a BA in Mathematics from Columbia University and in 1970 he received his MD from Thomas Jefferson University. He performed a rotating internship at the University of Chicago and subsequently completed a Radiology and Nuclear Medicine Residency at Massachusetts General Hospital. He received an MS in Public Health from Harvard University in 1975. He is a fellow of both the American College of Radiology and the American College of Nuclear Physicians. He is board certified in both radiology and nuclear medicine.

Dr. Mettler has authored over 360 scientific publications including 20 textbooks, and holds four patents. The books are on Medical Management of Radiation Accidents, Medical Effects of Ionizing Radiation and Radiology and Nuclear Medicine. He was a Scientific Vice President of NCRP and remains a member. He has chaired several committees for the Institute of Medicine/National Research Council and is a member of the Nuclear and Radiation Studies Board of the National Academies. He is also an academician of the Russian Academy of Medical Sciences. Dr. Mettler has been listed in "The Best Doctors in America" since 1994 as an expert in both nuclear medicine and radiation injury. He has been a certifying examiner for the American Board of Radiology for 30 y.

He was the United States Representative to the United Nations Scientific Committee on the Effects of Atomic Radiation 28 y. He is an Emeritus Commissioner of the International Commission on Radiation Protection (ICRP). He was the Health Effects Team Leader of the International Chernobyl Project. He has served as an expert on radiation effects and accidents for the Centers for Disease Control and Prevention, the World Health Organization, the International Atomic Energy Agency, the International Agency on Research on Cancer, and for the Costa Rican, Peruvian, Panamanian, Polish governments. He was a co-author of the NCRP and ICRP reports on radiation protection during radiological terrorism and has been a member of multiple subgroups on radiological terrorism for the U.S. Department of Homeland Security. He is currently a health advisor to the Japanese Cabinet for the Fukushima nuclear disaster.

fred a. mettler, jr.



recently retired as the Associate Director for Health for the National Health and Environmental Effects Research Laboratory of the U.S. Environmental Protection Agency (EPA). He also served as Director of the Environmental Carcinogenesis Division at EPA and as senior science adviser at the Chemical Industry Institute of Toxicology. He has been employed at the Biology Division of the Oak Ridge National Laboratory and has served as associate director for the Oak Ridge–University of Tennessee Graduate School for Biomedical Sciences. Dr. Preston's research and current activities have focused on the mechanisms of radiation and chemical carcinogenesis and the approaches for incorporating these types of data into cancer risk assessments.

Dr. Preston was chair of Committee 1 of the International Commission on Radiological Protection (ICRP), a member of the ICRP Main Commission, and a member of the U.S. delegation to the United Nations Scientific Committee on the Effects of Atomic Radiation. He is an associate editor of Environmental and Molecular Mutagenesis, Mutation Research, Chemico-Biological Interactions, and Health Physics. Dr. Preston has had more than 200 peer-reviewed papers and chapters published. He received his BA and MA from Peterhouse, Cambridge University, England, in genetics and his PhD from Reading University, England, in radiation genetics. He has served on the National Research Council's Committee to Assess the Scientific Information for the Radiation Exposure Screening and Education Program and the Task Group on the Biological Effects of Space Radiation.

r. julian preston



is President of Risk Assessment Corporation. He is a graduate of the U.S. Naval Academy and served in the U.S. Navy Nuclear Submarine Program and retired a Rear Admiral in the U.S. Naval Reserve in 1999. Dr. Till received an MS from Colorado State University in 1972 and a PhD from the Georgia Institute of Technology in 1976. In 1977 Dr. Till formed Risk Assessment Corporation to perform research on radionuclides released to the environment by nuclear facilities. His career has focused on the development of methods to estimate dose and risk to humans from radionuclides and chemicals in the environment. He has served on committees for the National Academy of Sciences, the International Commission on Radiological Protection, and the International Atomic Energy Agency. He has published widely in the open literature including the first textbook on radiological risk assessment published by the U.S. Nuclear Regulatory Commission in 1983 and an updated version, Radiological Risk Assessment and Environmental Analysis (2008).

In 1995, Dr. Till received the E.O. Lawrence Award from the U.S. Department of Energy in the field of Environmental Science and Technology. In addition to his scientific work, Dr. Till also owns and operates his family farm, growing corn and soybeans near Neeses, South Carolina.

john e. till
Wakeford R Richard Wakeford
No Image Linda Walsh



is Professor Emeritus and former Radiation Safety Officer at the Mayo Clinic in Rochester, Minnosota. He received his BS and MS degrees in Biology from South Dakota State University and his PhD in Health Physics from Purdue University. He is board certified by the American Board of Health Physics and the American Board of Medical Physics. He served on the Purdue University faculty from 1970 to 1980 and the Mayo Clinic staff and faculty from 1980 to 2010. Dr. Vetter is a member of the National Academies Nuclear and Radiation Studies Board, the Government Liaison for the Health Physics Society (HPS), and a member of the Executive Council of the International Radiation Protection Association. He is a Fellow of HPS and the American Association of Physicists in Medicine and received the HPS Founders Award.

He is past Editor-in-Chief of Health Physics, past president of HPS, past president of the American Academy of Health Physics, and author or coauthor of more than 220 publications, books, book chapters, and other articles. He served as Vice Chair of the U.S. Nuclear Regulatory Commission Advisory Committee for Medical Uses of Isotopes and member of the Radiation Advisory Committee of the U.S. Environmental Protection Agency Science Advisory Board. He served on the Board of Directors of NCRP, Chair of the NCRP Nominating Committee, and Chair of three and member of two NCRP scientific committees resulting in four NCRP reports and one NCRP statement. Dr. Vetter has received outstanding alumnus awards from South Dakota State University, the Purdue School of Pharmacy and Pharmacal Sciences, the Purdue School of Health Sciences, and the Purdue College of Health and Human Sciences.

richard j. vetter, Staff Consultant
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Last modified: March 15, 2017