The Relationship of Thyroid Cancer with Radiation Exposure from Nuclear Weapon Testing in the Marshall Islands.

Department of Public Health, Yamagata University School of Medicine, Iida-Nishi, Yamagata, Japan.
Journal of Epidemiology (Impact Factor: 3.02). 04/2003; 13(2):99-107. DOI: 10.2188/jea.13.99
Source: PubMed


The US nuclear weapons testing program in the Pacific conducted between 1946 and 1958 resulted in radiation exposure in the Marshall Islands. The potentially widespread radiation exposure from radio-iodines of fallout has raised concerns about the risk of thyroid cancer in the Marshallese population. The most serious exposures and its health hazards resulted from the hydrogen-thermonuclear bomb test, the Castle BRAVO, on March 1, 1954. Between 1993 and 1997, we screened 3,709 Marshallese for thyroid disease who were born before the BRAVO test. It was 60% of the entire population at risk and who were still alive at the time of our examinations. We diagnosed 30 thyroid cancers and found 27 other study participants who had been operated for thyroid cancer before our screening in this group. Fifty-seven Marshallese born before 1954 (1.5%) had thyroid cancer or had been operated for thyroid cancer. Nearly all (92%) of these cancers were papillary carcinoma. We derived estimates of individual thyroid dose proxy from the BRAVO test in 1954 on the basis of published age-specific doses estimated on Utirik atoll and 137Cs deposition levels on the atolls where the participants came from. There was suggestive evidence that the prevalence of thyroid cancer increased with category of estimated dose to the thyroid.

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    • "The main environmental risk factor for thyroid cancer reported in the literature is exposure of the thyroid gland to radiation. Potential sources that have been studied include radiation that comes from the atmosphere, ground water, energy plants, and medical procedures [14, 18–23]. It appears that younger age increases susceptibility to the effects of radiation on the thyroid gland. "
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    • "There is other evidence that early life exposure to radiation elevates risk for cancer later in life. Prepubertal children exposed to ionizing radiation from atomic bomb tests in the Marshall Islands from 1946 to 1958 developed thyroid cancer 15 to 29 years after exposure, but exposed adults had little or no increased risk [39] [40]. Similarly, after the accident at the Chernobyl nuclear reactor in 1986, an increased risk for thyroid cancer was found among individuals who were younger than 18 at the time of exposure, and their risk remained elevated for more than 2 decades. "
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