The Relationship of Thyroid Cancer with Radiation Exposure from Nuclear Weapon Testing in the Marshall Islands.
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.
[Show abstract] [Hide abstract] ABSTRACT: Background: Thyroid cancer is a common cancer in adolescents and young adults ranking 4th in frequency. Thyroid cancer has captured the interest of epidemiologists because of its strong association to environmental factors. The goal of this study is to identify thyroid cancer clusters in Florida for the period 2000-2008. This will guide further discovery of potential risk factors within areas of the cluster compared to areas not in cluster. Methods: Thyroid cancer cases for ages 15-39 were obtained from the Florida Cancer Data System. Next, using the purely spatial Poisson analysis function in SaTScan, the geographic distribution of thyroid cancer cases by county was assessed for clusters. The reference population was obtained from the Census Bureau 2010, which enabled controlling for population age, sex, and race. Results: Two statistically significant clusters of thyroid cancer clusters were found in Florida: one in southern Florida (SF) (relative risk of 1.26; P value of <0.001) and the other in northwestern Florida (NWF) (relative risk of 1.71; P value of 0.012). These clusters persisted after controlling for demographics including sex, age, race. Conclusion: In summary, we found evidence of thyroid cancer clustering in South Florida and North West Florida for adolescents and young adult.0Comments 2Citations
- "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. "
[Show abstract] [Hide abstract] ABSTRACT: Many chemical carcinogens are in food, water, air, household products, and personal care products. Although genetic susceptibility is an important factor in how an individual responds to exposure to a carcinogen, heritable genetic factors alone account for only a minor portion of cancer rates. We review the evidence that early life exposure to carcinogenic chemicals and ionizing radiation results in elevations in cancer later in life. Because cells are rapidly dividing and organ systems are developing during childhood and adolescence, exposure to carcinogens during these early life stages is a major risk factor for cancer later in life. Because young people have many expected years of life, the clinical manifestations of cancers caused by carcinogens have more time in which to develop during characteristically long latency periods. Many chemical carcinogens persist in the body for decades and increase risk for all types of cancers. Carcinogens may act via mutagenic, nonmutagenic, or epigenetic mechanisms and may also result from disruption of endocrine systems. The problem is magnified by the fact that many chemical carcinogens have become an integral part of our food and water supply and are in air and the general environment. The early life onset of a lifelong exposure to mixtures of multiple environmental chemical carcinogens and radiation contributes significantly to the etiology of cancer in later life.0Comments 8Citations
- "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  . 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. "
- "Ionizing radiation has been being described as the known major risk factor for thyroid cancer, especially papillary carcinoma, the most common thyroid cancer type (Nikiforov 2010). Convincing evidence exists of an association between exposure to external radiation and an increased risk of thyroid cancer (Mushkacheva et al. 2006; Pottern et al. 1990; Ron et al. 1995; Ron et al. 1989; Schneider et al. 1993; Shore et al. 1993; Shore et al. 2003; Yoshimoto et al. 1995); however, risks from internally deposited radioactive iodine were not well studied until recently (Zablotska et al. 2011; Kazakov, Demidchik, and Astakhova 1992; Shibata et al. 2001; Takahashi et al. 2003; Dobyns et al. 1974). Well-documented examples include medical therapeutic external beam radiation and accidental exposure to c-radiation and radioiodine as a result of nuclear weapon explosions or nuclear reactor accidents (Ron et al. 1995). "