The Million Person Study, whence it came and why

Abstract

Purpose

The study of low dose and low-dose rate exposure is of immeasurable value in understanding the possible range of health effects from prolonged exposures to radiation. The Million Person Study (MPS) of low-dose health effects was designed to evaluate radiation risks among healthy American workers and veterans who are more representative of today’s populations than are the Japanese atomic bomb survivors exposed briefly to high-dose radiation in 1945. A million persons were needed for statistical reasons to evaluate low-dose and dose-rate effects, rare cancers, intakes of radioactive elements, and differences in risks between women and men.

Methods and materials

The MPS consists of five categories of workers and veterans exposed to radiation from 1939 to the present. The U.S. Department of Energy (DOE) Health and Mortality study began over 40 years ago and is the source of ∼360,000 workers. Over 25 years ago, the National Cancer Institute (NCI) collaborated with the U.S. Nuclear Regulatory Commission (NRC) to effectively create a cohort of nuclear power plant workers (∼150,000) and industrial radiographers (∼130,000). For over 30 years, the Department of Defense (DoD) collected data on aboveground nuclear weapons test participants (∼115,000). At the request of NCI in 1978, Landauer, Inc., (Glenwood, IL) saved their dosimetry databases which became the source of a cohort of ∼250,000 medical and other workers.

Results

Overall, 29 individual cohorts comprise the MPS of which 21 have been or are under active study (∼810,000 persons). The remaining eight cohorts (∼190,000 persons) will be studied as resources become available. The MPS is a national effort with critical support from the NRC, DOE, National Aeronautics and Space Administration (NASA), DoD, NCI, the Centers for Disease Control and Prevention (CDC), the Environmental Protection Agency (EPA), Landauer, Inc., and national laboratories.

Conclusions

The MPS is designed to address the major unanswered question in radiation risk understanding: What is the level of health effects when exposure is gradual over time and not delivered briefly. The MPS will provide scientific understandings of prolonged exposure which will improve guidelines to protect workers and the public; improve compensation schemes for workers, veterans and the public; provide guidance for policy and decision makers; and provide evidence for or against the continued use of the linear nonthreshold dose-response model in radiation protection.

Keywords:

• Million Person (Worker) Study
• radiation epidemiology
• low-dose rate effects
• cancer
• heart
• cognition

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.

Notes

1 LNT refers to the linear-nonthreshold (LNT) dose-response model as used in radiation protection. Its purpose is to give regulators an approach to manage the potential risk of low-dose radiation exposures where radiation epidemiology is incapable of providing clear or convincing evidence or risk. It is inappropriate to use the LNT model in risk assessment for individuals or populations since it incorporates many assumptions and judgments that are not related to radiation risk (ICRP 2007; Boice 2017b; Shore et al. 2018; NCRP 2018b).

Additional information

Funding

This work was supported in part by a grant from the U.S. Nuclear Regulatory Commission (NRC-HQ‐60‐14‐G‐0011), grants from the Centers for Disease Control and Prevention (5UE1EH000989, 5NUE1EH001315), grants from the National Aeronautics and Space Administration (NNX15AU88G, 80NSSC17M0016), and grants from the U.S. Department of Energy (Grant No. DE-SC0008944 awarded to the National Council on Radiation Protection and Measurements, which included interagency support from the U.S. Nuclear Regulatory Commission, the U.S. Environmental Protection Agency, and the National Aeronautics and Space Administration; and more recent Grants No. DE-AU0000042 and DE-AU0000046). Contract support also was recently received from the Naval Sea Systems Command (N00024-17-C-4322). Further, contract support was received by Oak Ridge National Laboratory from the Office of Radiation and Indoor Air, U.S. Environmental Protection Agency, under Interagency Agreement DOE No. 1824 S581‐A1, under contract No. DE-AC05‐00OR22725 with UT-Battelle; and contract support was received by Oak Ridge Associated Universities from the U.S. Department of Energy under contract No. DE-SC0014664. The Radiation Nuclear Countermeasures Program of the National Institute of Allergy and Infectious Diseases (NIAID) provided support to the NCI under NIAID agreement #Y2-Al-5077.

Notes on contributors

John D. Boice

John D. Boice Jr. is President of the National Council on Radiation Protection and Measurements and Professor of Medicine at Vanderbilt University. He is an international authority on radiation effects and served on the Main Commission of the International Commission on Radiological Protection and on the United Nations Scientific Committee on the Effects of Atomic Radiation. He directs the Million Person Study of Low-Dose Health Effects.

Sarah S. Cohen

Sarah S. Cohen is a Principal Epidemiologist at EpidStat Institute where she directs observational research studies in the areas of pharmacoepidemiology, nutritional epidemiology, and occupational epidemiology as well as leads large data management projects and statistical analyses. She is also an Adjunct Assistant Research Professor of Medicine in the Department of Medicine at Vanderbilt University School of Medicine. She has been a collaborator on the Million Person Study of Low-Dose Health Effects for nearly 20 years, providing analytic support as well as co-authoring numerous publications.

Michael T. Mumma

Michael T. Mumma is the Director of Information Technology at the International Epidemiology Institute and the International Epidemiology Field Station for Vanderbilt University Medical Center. He has over 20 years of experience in data analysis and conducting epidemiologic investigations.

Elizabeth D. Ellis

Elizabeth D. Ellis currently works in the Health, Energy and the Environment Program, Oak Ridge Associated Universities. Dr. Ellis does research in Public Health, Occupational Health, and Epidemiology. A major project is contributing to the ‘Million Person Study.’ She is also active in human subject protection in research.