An Investigation Into the Prevalence of Thyroid Disease on Kwajalein Atoll, Marshall Islands

Abstract

The prevalence of thyroid nodules and thyroid cancer was studied in the indigenous population residing on Ebeye Island, Kwajalein Atoll, in the Republic of the Marshall Islands. This island, centrally located in the nation, is home to about 25% of the nation's population, many who have migrated there from other atolls. The objective of the study was to obtain thyroid disease rate statistics on as much of the population as possible that was alive during the years of nuclear testing and to test the hypothesis that described a linearly decreasing prevalence of palpable nodules with increasing distance from the Bikini test site. 1,322 Marshallese born before 1965 were given a thyroid examination using neck palpation, fine needle aspiration biopsy, and high resolution ultrasound imaging. Approximately 40% of the total population living on this island who are at risk from exposure to radioactive fallout during the years 1946-1958 were screened. Of that group, 815 were alive at the time of the BRAVO test on 1 March 1954. Two hundred sixty-six people with thyroid nodules were found (32.6%): 132 were palpable nodules (16.2%), and 134 were nodules that could be diagnosed with ultrasound only (15.7%). Prevalence of palpable nodules was particularly high in men and women older than 60 y, in men who were 6 to 15 y of age at the time of the BRAVO test, and in women 1 to 10 y of age at the time of the BRAVO test. In 22 people, the clinical diagnosis was most likely cancer though histopathological evidence was only available from 11 operated cases. Of the 11 operated cases, 10 were cancer. Cancer prevalence was particularly high in those women born between 1944 and 1953 (7/220 = 3.2%), i.e., who were children during the early years of nuclear testing. The Ebeye data showed a marginally significant correlation between palpable nodule prevalence among women and distance to Bikini (r = -0.44, p = 0.06). This report summarizes the clinical findings of the thyroid examinations, the age distributions for nodular disease and cancer, and examines the relationship between prevalence of nodules and present day levels of 137Cs in the environment of each atoll.

Risk of Thyroid Cancer in the Bryansk Oblast of the Russian Federation after the Chernobyl Power Station Accident

“…Marked increases in childhood thyroid cancer have since been reported for areas surrounding the Chernobyl reactor especially in Belarus and Ukraine (66)(67)(68). Pacini et al evaluated thyroid cancer cases reported from registries in Belarus since 1986 and compared them with presumably unexposed cases reported from registries in France and Italy (66).…”

“…In addition, the combined effects of deviations in more than one of these assumptions were investigated. The detailed results of these sensitivity calculations were provided in the Pilot Study Final Report (pages [55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74]. Based on the results, the following conclusions were reached:…”

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

“…The medical monitoring has been described in detail elsewhere. 8,11 Three study populations (birth cohorts) were defined: those born before the BRAVO test on March 1, 1954 (Bravo cohort), those born between March 1, 1954 and the end of the bomb test period (end-of-testing cohort), and those born between March 1, 1959 and January 1, 1965 (after testing cohort), the latter group to serve as unexposed control. The end-of-testing cohort included people who were in utero for more than three months at the end of the last atomic bomb detonation in August 1958 and thus were born before March 1, 1959 since the fetal thyroid actively concentrates iodine from the fourth month of gestation.…”

“…' We previously showed that thyroid nodules were very common, in particular in female Marshallese, and that the prevalence increased with age, but we found little evidence that benign thyroid nodules were related to exposure from nuclear fallout. [8][9][10][11] In 2001, we published a monograph that summarized our previous findings systematically. 11 In the monograph, we reported that the occurrence of thyroid cancer in Marshallese was still high in 40 years after the nuclear test and that the association between thyroid cancer prevalence and radio-iodines exposure using the data collected until the end of 2000.…”

The Possible Contribution of 129i in the Drinking Water and Food Supply to the Nodular Formation of Thyroid Tissue

“…Tumor development reaches a peak in 25-29 y. They have also been reported to develop as much as 40 -45 y later (Kasatkina et al 1997;Nikiforov and Fagin 1997;Schneider et al 1993;Hamilton et al 1987;Takahashi et al 1997;Cotterill et al 2001). Humans are subjected to radiation from external and/or internal radioactive sources.…”