eral forms of radioactive iodine in producing thyroid injury was more fully appreciated and accounted for the increased thyroid abnormalities noted (see Table 1). Several years after exposure, a trend toward retardation of growth was noted in some of the exposed Rongelap children,particularly in boys exposed when they were less thanfive years old (A-22,24). At ten years old, two boys, exposed at one year of age, became markedly stunted. In fact, they were shorter than their brothers who were a year younger. At this time, they exhibited clinical signs of severe loss of thyroid function. It was not immediately apparent that the growth retardation wasrelated to thyroid maifunction since the thyroid hormonelevels were normal. Soon after, a more refined test of thy- roid hormones showed that a form of protein in the blood, peculiar to the Marshallese people, had caused spurious readings of thyroid hormone levels. The hormonelevels were depressed and were responsible for the growth retardation. Nine years after exposure, thyroid nodules were detected in a 12-year-old Marshallese girl and the following year two other exposed children developed nodules of the gland. Tumors of population. Recurrence of non-cancerous tumors in two individuals following surgery has required a second operation. Table 3 lists the number andtypes of thyroid tumors diagnosed at surgery. The time of development of thyroid tumors was related to the amountof radiation to the gland.i.e., the greater the amountofradiation, the earlier the development of the tumor. Wefound later that the exposed Rongelap people generally showed reduced thyroid function, even those that had not had thyroid surgery (A-36); also, the degree of reduction in © those that had had surgery was greater than would be expected from the amountof thyroid gland which was removed (A-19). One exposed Utirik man, who had not had thyroid surgery, had slight reduction of thyroid function. A treatment program giving thyroid hormoneto Rongelap people, although not strictly adhered to, apparently prevented clinical effects of this reduced function. However, it was apparent that serious effects of loss of thyroid function could develop, and the importanceof maintaining a strict program of thyroid treatment was the thyroid gland,'! both benign and malignant, continued to develop in adults as weil as children, particularly in the exposed Rongelap group, to a lesser extent in the exposed Ailingnae, and, later, a slight increase was noted.in the lessear-expesedUtirikgroup. The — incidance ofthyroré.turmees4s (he dhéxpoad / group westhesame as in Scherrdpopila tionss About one-thirtofthe expoaddeTin pee: people haye developedthyroidabhéttha ies5 (see.Table 2); Thegreatest tattdencewastn”°= children exposed attess than 10‘yearsof'age, which is due to their smaller and more active thyroid glands. Two of the three Rongelap children exposed in utero later developed benign thyroid tumors, suggesting that radioiodines transferred from the motherto the fetus were partly responsible for development of the thy- : iva COM CeeRine Re rsely " rey ~ wh: stkinkbay Fa can yeep oF netNR cvs 2 ve OL 7? 5 roid tumors.*? The incidence of thyroid abnor- malities in the Utirik population has been slightly higher than that seen in the unexposed ‘lhe term “thyroid tumor” is used hareto include adenomatous nodules, adenomas and cancer. Reeentiy, a thyroid tumor wasfoundiin a Utirik man (one of eight) exposed in ucero. It is jess certain that bus tumor was related to the mother's exposure. Two Rongelap boys with growth retardation due to radiation effects on their thyroid glands. 23 s008i 14