A Comparison of Two Dose Assessment Methods for Exposures to Nuclear Detonation Radiation
A Comparison of Two Dose Assessment Methods for Exposures to Nuclear Detonation Radiation
Background:
- The National Cancer Institute was funded to study how much radiation U.S. veterans who served in the 1950s were exposed to. Researchers want to estimate how much radiation these veterans received. They will use two methods and compare them. One is to interview the veterans and study their military records. The other is to take blood samples and look for certain types of changes in the blood cells. Being exposed to some kinds of radiation is known to cause changes in blood cells. The amount of changes to these cells tells scientists about how much radiation was received.
Objectives:
- To better understand how to measure how much radiation a person has received.
Eligibility:
Design:
Understanding the potential consequences of exposures from nuclear detonations is a current national security concern. In the event of a nuclear detonation, an important priority for the scientific and national security community is to be able to estimate exposure to the general population for medical triage, treatment, follow-up and risk projection for public health purposes. The only available comprehensive exposure estimates for persons exposed to nuclear detonation radiation are from studies of wartime atomic bomb survivors. There is an urgent need to evaluate exposure assessment methods in other populations and to determine how well each works and the obstacles involved in the application of each.
In the absence of other studies of exposures to nuclear detonation radiation, the Atomic Veterans Epidemiologic Study (AVES)1, a large ongoing study of atomic veterans of 115,000 atomic veterans who participated in aboveground nuclear weapon tests during 1945-1962 provides a unique opportunity to evaluate the lasting biological effects of radiations received during nuclear detonations. That study has the means for identifying veterans who received the highest exposures as well as control subjects with minimal to no exposure. An overview of the AVES can be found at http://www.vbdr.org/meetings/2013/Presentations/02\_Dr\_Boice.pdf.
We propose to conduct a small methodologic investigation with the following objective: evaluate the level of agreement between radiation exposure estimates from the generally simple and inexpensive assessment strategy of model-based dose reconstruction with the only well-established long-term biologically-based dose estimation technique - quantification of chromosome aberration frequency. In this study, the dose reconstruction would include individual interview data.
The study would be conducted using a group of U.S. veterans exposed to nuclear detonation radiation during the 1950s and 1960s. While there are many thousands of veterans still alive today who participated in nuclear testing-related activities, only 16 have been identified that are still living and that have estimated exposures of sufficient magnitude for the chromosome aberration frequency assay to be successful. These particular veterans were exposed on Rongerik Atoll in the Pacific in 1954 and at the Nevada Test Site in 1951-1952. The dose estimates will also be compared against individual records of exposure obtained from radiation film-badges, when available. All the persons to be studied are part of the study cohort in the AVES study.
The primary purpose of evaluating the model-based dose reconstruction with the dose estimates based on chromosome aberration frequency will be to assess the presence of any substantial differences (either systematic or random) in doses now being estimated via model-based dose reconstruction in the AVES. Because the chromosome aberration frequency assay is difficult, expensive and somewhat invasive (requiring a blood sample), it is not practical in a study of many thousands of subjects as in the AVES. Determination that the model-based dose estimations are not systematically different from FISH-estimated doses is of substantial value to the AVES. To a limited degree, i.e., within the constraints of the small sample size, the study may be indicative of the potential for model-based dose estimates to be relied upon if mass exposures were to take place from a nuclear detonation.
It is noteworthy that the collection of samples and data to evaluate doses in this study will take advantage of a one-of-a-kind situation to obtain exposure-related data from a unique (and rapidly dwindling) population living persons exposed to atomic weapons detonation radiation a situation that cannot be repeated except under wartime or actual national threat situations.
EXPOSED VETERANS. Subjects for this investigation are required to have received, according to military records, whole-body radiation doses in excess of 0.25 Sv to ensure adequate detection of the radiation exposure by the FISH method. The recorded doses are crude dose estimates, often based on group radiation monitoring rather than on individual data, however, they are the only information available, upon which to select the study subjects that meet our criteria.
To date, 16 exposed veterans that meet this requirement have been identified by the AVES through accessing databases of the NTPRP constructed by the Dept. of Defense.