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ORAU is playing a key role in the design and execution of the largest-of-its kind study of more than one million United States workers on the effects of long-term exposure to low-dose radiation. The Epidemiologic Study of One Million Persons, or “Million Persons Study” (MPS) is a national effort and the largest epidemiologic study of radiation exposure. The MPS strives to provide increased precision in risk estimates.

The study population includes: uranium and plutonium workers at multiple Department of Energy (DOE) locations, nuclear weapons test participants (atomic veterans), nuclear power plant workers, industrial radiographers, and medical workers (radiographers, radiologists, and other medical practitioners).

ORAU is partnered with the National Council on Radiation Protection and Measurements, Oak Ridge National Laboratory, Vanderbilt University and other non-profit organizations. The study has been supported by multiple government agencies such as DOE, National Cancer Institute, Nuclear Regulatory Commission, National Aeronautics and Space Administration, Centers for Disease Control and Prevention, and United States Navy.

Launched in 2012, the foundation of the MPS is a data center, constructed by ORAU, that captures 70+ years of occupational radiation data, dating from 1942 to present. In addition to the data access and data management, ORAU provides historical knowledge of DOE operations, as well as subject matter expertise in occupational epidemiology, radiation dose assessment and biostatistical modelling. 

An innovation and strength of the study are the methods used to assess internal organ dose resulting from radiation exposure that combines internal and external exposure to derive an overall organ dose. Such comprehensive dosimetry is required to produce the best radiation risk estimates for addressing current radiation issues on the effectiveness of low dose-rate exposures.

These estimates are relevant to:

  • Projecting risks from environmental contamination from nuclear waste, terrorist events, and radiations used in medical diagnosis or treatment;
  • Compensation issues related to prior exposures; improved protection standards for workers and the public; evaluation of the safety and radiation risks for astronauts leaving Earth’s orbit; and
  • Appropriateness of the linear non-threshold model as a principle for radiation protection guidance.

Contact us

For more information about ORAU's worker health and safety programs, contact us at 865.576.3115 or .

For more information about contracting with ORAU, contact Dominic Moro at 865.241.1446 or