Suchergebnisse

Following the earthquake and tsunami in northern Japan on 11 March 2011, and the ensuing damage to the Fukushima Daiichi nuclear power plant complex, a request by the U.S. Ambassador to Japan to the U.S. Department of Health and Human Services (DHHS) Assistant Secretary for Preparedness and Response (ASPR) resulted in deployment of a five-person team of subject matter experts to the U.S. Embassy. The primary purpose of the deployment was to provide the U.S. Embassy in Tokyo with guidance on health and medical issues related to potential radiation exposure of U.S. citizens in Japan, including employees of the U.S. Department of State at consulates in Japan and American citizens living in or visiting Japan. At the request of the Government of Japan, the deployed health team also assisted Japanese experts in their public health response to the radiation incident. Over a three-week period in Japan and continuing for weeks after their return to the U.S., the team provided expertise in the areas of medical and radiation oncology, health physics, assessment of radiation dose and cancer risk, particularly to U.S. citizens living in Tokyo and the surrounding areas, food and water contamination and the acceptable limits, countermeasures to exposure such as potassium iodide (KI), the use of KI and an offered donation from the United States, evacuation and re-entry issues, and health/emergency-related communication strategies. This paper describes the various strategies used and observations made by the DHHS team during the first two months after the Fukushima crisis began.

It has now been over 60 years since U.S. nuclear testing was conducted in the Pacific islands and Nevada, exposing military personnel to varying levels of ionizing radiation. Actual doses are not well-established, as film badges in the 1950s had many limitations. We sought a means of independently assessing dose for comparison with historical film badge records and dose reconstruction conducted in parallel. For the purpose of quantitative retrospective biodosimetry, peripheral blood samples from 12 exposed veterans and 12 age-matched (>80 years) veteran controls were collected and evaluated for radiation-induced chromosome damage utilizing directional genomic hybridization (dGH), a cytogenomics-based methodology that facilitates simultaneous detection of translocations and inversions. Standard calibration curves were constructed from six male volunteers in their mid-20s to reflect the age range of the veterans at time of exposure. Doses were estimated for each veteran using translocation and inversion rates independently; however, combining them by a weighted-average generally improved the accuracy of dose estimations. Various confounding factors were also evaluated for potential effects on chromosome aberration frequencies. Perhaps not surprisingly, smoking and age-associated increases in background frequencies of inversions were observed. Telomere length was also measured, and inverse relationships with both age and combined weighted dose estimates were observed. Interestingly, smokers in the non-exposed control veteran cohort displayed similar telomere lengths as those in the never-smoker exposed veteran group, suggesting that chronic smoking had as much effect on telomere length as a single exposure to radioactive fallout. Taken together, we find that our approach of combined chromosome aberration-based retrospective biodosimetry provided reliable dose estimation capability, particularly on a group average basis, for exposures above statistical detection limits.

In recent years, the prospects that a nuclear device might be detonated due to a regional or global political conflict, by violation of present nuclear weapons test ban agreements, or due to an act of terrorism, has increased. Thus, the need exists for a well conceptualized, well described, and internally consistent methodology for dose estimation that takes full advantage of the experience gained over the last 70 y in both measurement technology and dose assessment methodology. Here, the models, rationale, and data needed for a detailed state-of-the-art dose assessment for exposure to radioactive fallout from nuclear detonations discussed in five companion papers are summarized. These five papers present methods and data for estimating radionuclide deposition of fallout radionuclides, internal and external dose from the deposited fallout, and discussion of the uncertainties in the assessed doses. In addition, this paper includes a brief discussion of secondary issues related to assessments of radiation dose from fallout. The intention of this work is to provide a usable and consistent methodology for both prospective and retrospective assessments of exposure from radioactive fallout from a nuclear detonation.