mee em neewater | SM A ee -7During the two-day period following the accident before the evacuation of the people occurred, the inhabitants absorbed radionuclides in the fallout by inhalation and ingestion of contaminated food and drinking water. Based on radiochemical analyses of pooled urine samples taken several weeks after the accident it was estimated that the adult thyroid gland in the main Rongelap group received about 160 rads from the radioiodine plus another 175 rads from the external gamma radiation. Taken into consideration in those calculations were the time and length of the fallout period, the isotope energies and half-lives of the various iodine nuclides, and the yield of the isotopes. Similar estimates for the smaller thyroid glands of the young children ranged from 700 to 1400 rads in the more heavily exposed group. Though "beta burns" were prevalent in the neck region, it is believed the beta energies were too weak to have contributed significantly to the thyroid dose. The thyroidsa of the Utirik children received an estimated 55 to 125 rads from iodine, plus the 14 rads from external gamma radiation. In 1963, 9 years after exposure to fallout, the first thyroid nodule was detected in a 12-year-old girl in the more heavily exposed group, and 2 further nodules were detected in 1964. In March, 1965, 5 other cases were noted and in addition hypothyroidism was diagnosed in two boys who had shown growth retardation. Five further cases were detected in Septenber of 1965 and 5 more in March, 1966, making a total now of 16 cases with nodules plus two cases of hypothyroidism, 19 Only one nodule was found to be malignant. These cases are described in Table I (page 11). Table II (page 13) summarizes the incidences of thyroid abnormalities in the various populations examined. Note that 79 percent of children less than 10 years of age at time of exposure in the more heavily exposed group developed ~ thyroid abnormalities, in comparison with no thyroid pathology noted in children of the same age range of the non-exposed population or in the lesser exposed populations. The incidence in those exposed at a greater age is considerably lower, and only slightly above that seen for the unexposed or less exposed populations. It should be noted that the only nodules noted in the unexposed population were in the older age group, that is, greater than 50 years of age. In most cases the thyroid glands contained multiple nodules ranging in diameter from a few millimeters to a few centimeters. All were nontender, some firm, others cystic, and Sometimes even hemorrhagic. No lymphadenopathy was noted. The microscopic sections of the benign lesions showed quite bizarre appearance with a wide variety of different sized follicles, some small and atrophic, others large with hyperplasia or cystic formation. The hyperplastic changes were characterized in some cases by infolding of the epithelium giving an arboreal appearance. These changes resemble those seen in iodine deficiency goiter (adenomatoid goiter). The one case of cancer of the thyroid occurred in a 42-year-old woman and was of the mixed papillary and follicular type. A hypothyroid etiology for growth retardation noted in children in the exposed group is strongly suggested by the findings of definite hypo- DOE ARCHIVES 10. onard, R. A.: Personal Commmication.