Is this the first large cohort study of radiation workers?
There have been several international collaborations that have included large numbers of radiation workers. One of the first was published in 1995 and included 95,000 workers from three countries (United States, United Kingdom and Canada). This 3-country study was subsequently expanded to a 15-country study and included some 400,000 radiation workers and was published in 2005. The current study is over twice as large as any previous study and, because it focuses on early workers in the U.S., for example those involved in the Manhattan Project as well as early radiologists, the follow-up for late effects is longer than that of other studies including the Japanese atomic bomb survivors, for which the exposure was in 1945.
Is the One Million U.S. Radiation Workers study comparable to any other investigation?
While there have been other international studies of occupational workers, the One Million U.S. Radiation Workers study is unique by focusing on early workers in the U.S., has larger numbers and longer follow-up than most previous studies and will incorporate internal intakes of radionuclides, which has rarely if ever been done in previous investigations.
How do you know that the study is feasible?
A comprehensive study of Rocketdyne (Atomics International) workers was conducted that demonstrated the feasibility of the approach to be taken. This approach was further enhanced in a pilot study initiated in 2010 and funded by the DOE for which rosters of workers and their existing dosimetry has been obtained on nearly 800,000 workers to date. In addition, and separate from this project in terms of funding and execution, but in collaboration with Vanderbilt, a U.S. National Institutes of Health grant was awarded to study the 120,000 atomic veterans included in previous cohorts to extend the follow-up and conduct comprehensive dose reconstructions for dose-response analyses. A second follow-up of the Rocketdyne (Atomics International) worker population has been completed and manuscript accepted for publication, and a second follow-up of the Mound worker population, with a focus on internal polonium exposures, is nearing completion.
How long will the One Million U.S. Radiation Workers study last?
The initial idea for the study of One Million U.S. Radiation Workers germinated in 2007 at a workshop held in Oak Ridge, Tennessee. Pilot funding was subsequently received from the DOE to develop the methods for studying such a large group of early U.S. radiation workers and evaluating feasibility. The pilot study will last through mid-2011. A full-scale study would be anticipated to last approximately five years and through about 2016. Continued follow-up at that time would then be considered to obtain additional information on lifetime radiation risks.
What is the purpose of this study?
The study of a million U.S. workers and military veterans would provide a definitive evaluation of risks associated with low-dose radiation exposures experienced over a prolonged period of time. This is the one area of scientific investigation for which strong evidence for effects is lacking.
Who will benefit from this study?
The purpose of the investigation is to provide a definitive evaluation of risk associated with low-dose radiation exposures experienced over a prolonged period of time. The implications are multi-faceted and include:
Protection standards for workers and the general population
Assessment of risk associated with the enhanced medical technologies, such as CT and nuclear medicine imaging
Expansion of nuclear power
Handling of nuclear waste
Compensation to workers with prior exposures to ionizing radiation
A service to U.S. workers and veterans and their families by providing a sound understanding of the risks they may have incurred while working in service to their country
Who We Study and How
How many workers are expected to be enrolled in the study?
Approximately one million U.S. radiation workers or atomic veterans will be enrolled in the study. Currently the cohorts include approximately 360,000 workers at the DOE nuclear weapons and processing facilities, 120,000 nuclear weapons test participants (atomic veterans), 200,000 nuclear power plant workers, and over 200,000 early radiation workers (primarily medical, but also industrial radiographers and research personnel).
How were workers selected for the study?
A wide net was cast to select the majority of early radiation workers in the U.S. for which radiation dosimetry was available or could be readily obtained. The DOE workers had been previously studied over the years, but a recent follow-up of workers at the over 20 facilities throughout the U.S. had not been conducted. The atomic veterans had been studied by the Medical Follow-Up Agency of the National Academies of Science, as well as the VA, and these previous populations in four cohort studies were available for subsequent follow-up and evaluation in a cost-effective manner. The nuclear power plant workers are being selected from the dosimetry files of Landauer Inc. with enhancements by the NRC REIRS database. It is hoped that early workers at specific nuclear power plants can be added to supplement the existing rosters. The "early radiation workers" cohort is currently identified as those who received >5 rem cumulative exposure within the Landauer Inc. computerized data files and microfilm files. Other populations of interest include the cohorts of U.S. Navy nuclear submariners as well as naval shipyard workers, but have not yet been pursued for possible inclusion. The selection criteria for workers to be included in the One Million U.S. Radiation Workers study includes focusing on epidemiologic cohorts that had been previously studied so that the extended follow-up could be conducted in an effective and cost-efficient manner. Populations with individual dosimetry are selected as well as those employed or exposed in the early days of nuclear activities in the U.S.
How are radiation doses calculated?
The dose reconstruction program will be as comprehensive as possible. The model followed will be that of our recent study of the Rocketdyne (Atomics International) workforce for which linkages were made to capture all career occupational doses, including those at DOE facilities, military installations, the NRC REIRS database, the DOE REMS database, as well as individual nuclear facilities. In addition, comprehensive internal radiation dosimetry is being conducted with the focus on radionuclides, such as polonium, uranium, plutonium, tritium, among others. The Oak Ridge National Laboratory is taking the lead role in these evaluations, which include incorporating information available from bioassay measurements, biokinetic models that have been developed over the years, and also probabilistic dose reconstruction models that have been recently developed to enhance and address the uncertainties associated with radiation dose estimation.
Who We Are
Who is conducting the study?
The International Epidemiology Institute is the lead institution directing the study. However, there are many participating and collaborating institutions whose involvement make the study possible. These collaborators include the Oak Ridge Associated Universities, Oak Ridge National Laboratory, Los Alamos National Laboratory, Vanderbilt University, Landauer Inc., University of Southern California and Harvard Medical School. Currently the cooperating government agencies include the U.S. Department of Energy (DOE), the U.S. Nuclear Regulatory Commission (NRC), the U.S. Department of Defense (DOD), the U.S. Department of Veterans Affairs (VA) and the National Cancer Institute (NCI).
Who is paying for this study?
Initial scoping efforts were supported by a Discovery Grant from the Vanderbilt-lngram Cancer Center (Center No. 404-357-9682). Subsequently, the ongoing pilot study is funded by a DOE research grant (Grant No. DE-SC0004307) to the International Epidemiology Institute, and a contract between the DOE and Oak Ridge Associated Universities (Contract No. DE-AC05-06OR23100). A separate but associated component of the One Million U.S. Radiation Worker study entitled "Cancer Mortality among Military Participants at U.S. Atmospheric Nuclear Weapons Tests" is supported by a cooperative agreement grant from the NCI (Grant No. UO1 CA137026) to Vanderbilt University.
Who will provide oversight of the study?
Oversight will be provided by an advisory committee that includes national and international experts on studies of radiation workers and radiation effects.
Where is the study taking place?
The study is taking place throughout the United States and includes working sites in Maryland, Tennessee, New Mexico, Illinois, California, Massachusetts, Washington and South Carolina.