News Media Resources: DTRA Fact Sheet - Radiation Exposure in U.S. Atmospheric Nuclear Weapons Testing (Nuclear Test Personnel Review Program)
Radiation Exposure in U.S. Atmospheric Nuclear Weapons Testing (Nuclear Test Personnel Review Program)
(Toll Free Hot Line: (800) 462-3683)
The Defense Threat Reduction Agency (DTRA) is the Department of Defense (DoD) Executive Agent for the Nuclear Test Personnel Review (NTPR) Program, which serves veterans who participated in U.S. atmospheric nuclear tests, served with the American occupation forces of Hiroshima and Nagasaki, Japan, or were prisoners of war in Japan at the conclusion of World War II. The primary purpose of the NTPR Program is to provide participation data and radiation dose information to veterans.
U.S. Atmospheric Nuclear Tests
Approximately 230,000 DoD military and civilian personnel participated in U.S. atmospheric nuclear tests that were conducted primarily in Nevada and the Pacific Ocean between 1945 and 1962. Many participants were exposed to low levels of ionizing radiation while performing various activities. Over 99 percent of these participants received radiation doses that were below the current federal occupational whole body dose limit (5 rem per year). The average whole body dose was about 0.6 rem. Current occupational dose limits for DoD personnel are codified in DoD Instruction 6055.8 (DODI 6055.8) and are based upon the Environmental Protection Agency's "Radiation Protection Guidance to Federal Agencies for Occupational Exposure" (1987).
Hiroshima and Nagasaki Occupation Forces
Approximately 230,000 veterans participated in the post-World War II occupation of Hiroshima and Nagasaki, Japan, or were prisoners of war in these areas. Over 95 percent of these participants received radiation doses below 0.1 rem. Only those Nagasaki occupation forces that regularly entered the Nishiyama area had the potential to receive doses up to 1 rem.
Units and Risk Facts
The "rem" is the traditional unit of radiation dose used to quantify the biological effect of ionizing radiation (gamma, x-ray, beta, neutron or alpha) in humans. Ionizing radiation is capable of displacing electrons from atoms or molecules, thereby producing ions. By comparison, other radiations such as microwaves and lasers are not capable of producing ions and are therefore examples of non-ionizing radiation. According to Report 93 of the National Council on Radiation Protection and Measurements (NCRP), members of the general U.S. population receive approximately 0.36 rem per year from natural background radiation sources (such as radon and cosmic rays) and man-made radiation sources (such as medical procedures, x-rays, and consumer products). As a basis of comparison, a standard diagnostic chest x-ray delivers a radiation dose of about 0.02 rem. Copies of NCRP Report 93 may be purchased from the NCRP (800-229-2652).
Scientists generally agree that the current federal occupational whole body dose limit (5 rem per year) carries a low risk of causing additional cancers above the level normally observed in the general population (20 excess fatal cancers in an exposed population of 10,000). The Health Physics Society states that the risk of health effects are either too small to be observed or are nonexistent at doses below 5 rem, and that radiogenic health effects have not been consistently demonstrated below 10 rem (Radiation Risk in Perspective, 2004).
According to the American Cancer Society (ACS) and the National Cancer Institute (NCI), the lifetime risk of developing any type of cancer for members of the U.S. population is greater than 40 percent (Cancer Facts and Figures 2005, SEER Cancer Statistics Review 1975-2002). In fact, ACS states that a man's lifetime risk for developing cancer is slightly less than one in two. The risk of being diagnosed with cancer generally increases with age, as evidenced by the fact that approximately three out of every four cancers are diagnosed in persons 55 and older. For further information on cancer incidence and diagnosis, contact ACS (404-320-3333) or NCI (800-4-CANCER).
Film Badges
The most common method for measuring dose from ionizing radiation at U.S. atmospheric nuclear tests was the issuance of a film badge. Of the 230,000 DoD participants at U.S. atmospheric nuclear tests, about 45 percent have recorded doses from film badges. None of the Hiroshima or Nagasaki occupation forces were issued film badges. The majority of films from these badges are maintained by the Department of Energy at the Nuclear Testing Archive in Las Vegas, Nevada (702-295-1628). Film badges are frequently examined and reevaluated whenever the registration of a film badge dose requires validation.
Until 1955, the availability of film badges varied. There were situations in which a group of personnel, such as a platoon or ship/aircraft crew, experienced similar conditions and were assigned a single film badge to represent the radiation dose for every individual in the cohort (group). The practice of monitoring a group in this manner was chosen because every member of the group performed similar work in roughly the same radiological environment over a similar duration of time.
After 1955, the DoD and the Atomic Energy Commission changed their policies to require that all participants having the potential for radiation exposure at an atmospheric test site be issued a film badge. Some film badges were damaged (by heat, humidity, and other causes), rendering them unreadable. A small number of film badges were issued and not returned or were lost before they could be analyzed.
For further information on film badges, see the National Academy of Sciences (NAS) report entitled "Film Badge Dosimetry in Atmospheric Nuclear Tests."
Reconstructed Doses
When radiation doses from film badges are not available, the NTPR Program performs dose reconstructions to calculate a dose from information contained in other records. These records include instrument readings from radiological surveys, aircraft penetration of nuclear clouds, and laboratory results of analyses. As a result, a significant portion of the NTPR effort has focused on characterization of radiological environments and developing technical assessment procedures to assess doses for personnel who were not issued film badges or personnel whose records are missing or incomplete.
Dose Reconstruction Methodology
In 1985, the NTPR dose reconstruction methodology was published in Title 32, Code of Federal Regulations, Part 218 (32 CFR 218). This methodology has been developed to provide a comprehensive analysis of both external and internal radiation doses, for application to units as well as individuals. Since 1985, the scientific methods used by the NTPR Program have been reviewed several times by the Government Accountability Office (GAO) and the NAS, most recently in 2003. See the NTPR Studies and Review fact sheet for more information on the results of these program reviews.
The NTPR Program uses the following three alternative approaches, as described in 32 CFR 218, to determine the radiation dose to individuals for whom film badge data are not available:
Determination of dose potential. Activities of an individual or their unit for the period of participation are researched. Unit locations and movements of the veteran are related to areas of radioactivity and radiation exposure. If personnel were beyond the range of initial radiation exposure from nuclear detonations (several miles), were not exposed to fallout, did not enter a radiologically contaminated area, and did not come into contact with radioactive materials, the dose evaluation will conclude that no radiation dose was received.
Dose based on, film badges of others. Film badge data from badged personnel are used to derive individual radiation doses for unbadged personnel. A homogeneous group of participants is identified, consisting of personnel who performed common activities and therefore had a similar potential for radiation exposure. Identification of homogeneous groups is based upon research of historical records, technical reports, and correspondence. Using standard statistical methods, the film badge data are examined along with unit records and any available statements/questionnaires concerning the veteran's activities to determine whether it is valid to assign an entire group's average radiation dose to an individual. Often the dose or the periods over which film badges were worn indicate that the group should be further subdivided into personnel performing common functions before proceeding with the analysis. For each homogeneous group, the mean and upper-bound radiation doses are obtained from the distribution of film badge readings. The upper-bound dose is the value corresponding to a 95 percent probability that the actual dose received by the veteran is lower. This procedure ensures that unbadged personnel are provided mean and upper-bound radiation doses that reflect the uncertainties exhibited by the spread of film badge readings within their homogeneous group. If individuals cannot be associated with a specific homogeneous group, then film badge doses for this group are not used.
Dose calculation. In accordance with 32 CFR 218, rigorous dose calculations are performed when film badge data are unavailable for all or part of the exposure period. The NTPR Program also performs calculations if film badges were damaged and cannot yield reliable dose information, if unique activities are credited to specific individuals, or if a neutron dose or a dose to the skin or an internal organ is necessary. These calculations involve correlating the activities of an individual (as described in statements/questionnaires/interviews) with the radiological environments encountered.
Dose Calculation Process
The calculation of radiation dose is a scientific practice commonly employed by health physicists when an individual's radiation exposure cannot be quantified by dosimetry (such as a film badge). The general process of radiation dose assessment and reconstruction for veterans is described here:
The conditions of radiation exposure are reconstructed to include all known activities based on statements/questionnaires from the veteran, as well as information from official reports and historical documents. These statements/questionnaires/interviews form the basis for documenting the veteran's activities and are subsequently used along with radiological information to provide dose information.
The radiation environment is characterized in time and space, and matched with the activities and locations of the unit or individual. In addition to external gamma radiation measured by film badges, the contributions from other types of radiation (such as neutrons) are considered and included.
Individual activities, as documented by statements/questionnaires/interviews from the veteran (including available shielding, body position, and other factors) are quantitatively associated with radiological environment information and a total integrated dose is calculated.
Any available and valid (undamaged and otherwise scientifically accurate) film badge dosimetry is analyzed and compared with the calculated radiation dose to establish correlation confidence to the calculations.
An uncertainty analysis is performed to consider the relative sensitivities of all parameter inputs and to provide an upper-bound radiation dose estimate (95th percentile).
Internal Dose
Where the potential existed for inhalation or ingestion of radioactive materials or fallout, internal dose commitments from alpha, beta and gamma radiation to the relevant target organ are derived. Since radioactive materials entering the body deliver their dose over a period of time (rather than instantly), internal radiation doses are determined for a 50-year period after the initial exposure, even if this period extends beyond the actual or expected lifetime of the veteran.
Comparison of Reconstructed Doses with Film Badge Records
Prior to implementation of the NTPR dose reconstruction methodology, it was applied to specific scenarios in which film badge data were available to determine if the methodology could accurately predict the film badge results. All parameters relating to radiation exposure (such as body position and activities performed) were identified, allowing the reconstructed dose to be directly compared to actual film badge readings. The resulting correlations were in satisfactory agreement and provided a high degree of confidence that NTPR dose reconstruction methodologies, as codified in 32 CFR 218, accurately predict film badge results.
Dose Information Requests
The NTPR Program can provide veterans with information relevant to their radiation exposure, and dose requests may originate from veterans, their representatives (as authorized under the Privacy Act), the VA, or Congress. However, obtaining confirmation of participation or a radiation dose estimate from the NTPR Program is not a prerequisite to filing a claim or obtaining priority health care.
The radiation dose reconstruction process, as outlined above, is based upon the evaluation of existing records and any available statements/questionnaires/interviews concerning the veteran's activities. Veterans wishing to assist the NTPR Program with confirmation of participation or a dose reconstruction may provide copies of military records to the NTPR Program.
NTPR Inquiries
Veterans desiring service or seeking information about the NTPR Program can address their inquiries to:
Nuclear Test Personnel Review Program
DTRA/TDND
8725 John J. Kingman Road
MSC 6201
Fort Belvoir, VA 22060-6201
Phone: 800-462-3683
Email: [email protected]
