~y MEN NAL TNS ae ee ce Tr b> SUS ERI M2 SRE OG IZCTED . as COPYRIGHT Law ‘TITLE 17 U.S. CODE: BEST AVAILABLE COPY 67399 Ayes by fee ote a ah a yg. on os ° aa Saeed taal edles Maa Thyroid Neoplasia in Marshall Islanders Exposed to Nuclear Fallout Thomas E. Hamilton, MD, PhD: Gerald van Belle, PhD; James P. LoGerfo, MD, MPH We studied the risk of thyroid neoplasia in Marshall Islanders exposed to radioiodines in nuclearfallout from the 1954 BRAVO thermonuclear test. We screened 7266 Marshall Islanders for thyroid nodules;the islanders were from 14 atolls, including several southern atolls, which were the source of the best available unexposed comparison group. Using a retrospective cohort design, we determined the prevalenceof thyroid nodularity in a subgroup of 2273 persons who were alive in 1954 and whotherefore were potentially exposed to fallout from the BRAVOtest. For those 12 atolls previously thought to be unexposed to fallout, the prevalence of thyroid nodules ranged from 0.9%to 10.6%. Using the distance of each atoll from the test site as a proxy for the radiation dose to the thyroid gland, a weighted linear regression showed an inverse linear relationship betweendistance and the age-adjusted prevalenceof thyroid nodules. Distance was the strongestsingle predictor in logistic regression analysis. Anew absolute risk estimate was calculated to be 1100 excess cases/Gy/y/1 x 10* persons (11.0 excess Cases/rad/y/1 million persons), 33%higher than previous estimates. We conclude that an excess of thyroid nodules was not limited only to the two IT HASbeen 21 years since the publication of an early case series of thyroid neoplasia (including thyroid cancer and From the Departments of Medicine (Drs. Hamilton and LoGerfo) and Biostatistics (Or van Belle}, University of Washington, Seattle. The opinions, conclusions, and proposais in this article are those of the authors and do not necessarily representthe views of the Robert Wood Johnson Foundation or tha Marshall Islands Atornic Testing Litigation Project. . Reprint requests to Occupational Medicine Program, Harbormew Medicat Center, 325 Ninth Ave, Seattie, WA 98104 (Dr Hamilton). JAMA, Aug 7, 1987—Vol 258, No. 5 _ commonlate effect from this exposure has been the development of thyroid nodules. Between 1954 and 1985, thyroid nodules developed in approximately 33% of the Rongelap population, including 63% of children less than 10 years old at the time of exposure, and 10% of the Utrik population.*”* Previous investigators have assumed that Rongelap and Utrik were the only two northern atolls exposed to fallout radiation; in their studies they used as unexposed controls those living on other northern atolls during the 1954 BRAVOtest and benign nodules) developing in children of Marshall Islanders as a late effect of exposure to radioactive fallout.’ This exposure resulted from the detonation of a 15-megaton thermonuclear device on March 1, 1954, on Bikini Atoll in the northern Marshall Islands (Fig 1). This atmospheric nuclear test, code-named found the prevalence of thyroid nodules in this comparison group to be 6.3%.”* Although the estimates of thyroid dose for islanders from Rongelap and Utrik have been widely published, almost no information exists about the possible contamination of other northern atolls by radioiodines in 1954.*"*"" There is no verification that exposure to radioiodine did not occur on the other northern atolis. Radiation exposure to the thyroid gland in the Marshallese people resulted primarily from beta radiation from a mixture of radioiodines (I, “I, ™1, I) and, to some extent, gamma lands of Rongelap Atoll (86 inhabitants), and to a lesser extent, Utrik Atoll (167 inhabitants), The acute radiation sickness that developed in mostof the people from Rongelap has been well de- tion-induced thyroid neoplasia comes largely from two sources: (1) studies of children exposed to gamma radiation for benign diseases*™ and(2) studies of survivors exposed to gammaradiation northern atolls but extended throughout the northernatolls; this suggestsa linear dose-response relationship. scribed in previous reports.*" The most (JAMA 1987;258:629-636) BRAVO, heavily contaminated the is- radiation.*"” Knowledge about radia- Thyroid Neoplasia—Hamilton et al 629