31 13 and 18 years of age and in a 41-year-old decided that 5 such cases should be brought to the thyroidism in growth-retarded boys were also noted at this time. In September 1965 a further examination wascarried out by two of us (R.A.C. and J.E.R.), and 5 more exposed people were found with nodules varying in size from 2 to 8 mm. One of these was a 45-year-old woman in the group that received only an estimated 69 rads. Thecases up to this point were recently reviewed." In March 1966 nodules of the thyroid gland were detected in 5 additional exposed children. Table 17 gives some pertinent dataon all these cases. Table 18 showsthe distribution of the thyroid abnormalities (nodules and hypothyroidism) by age. In Table 19 results are presented on the various populations studied along with the estimated radiation doseto the thyroid gland. It is noteworthy that the preponderanceof thyroid abnormalities tion in nodule size, though presumably they had woman, the first adult case. Two cases of hypo- have occurred in children exposed at <10 years of age and only in the more heavily exposed group (15 of 19 children, 78.9%). No cases with thyroid abnormalities were detected in the children in the lower exposure groupsof the same age range (6 Ailingnae children, 40 Utirik children) or in the 61 unexposed Rongelap children. Two adults with thyroid nodules were noted in the more heavily exposed Rongelap group and onein the Ailingnae group. In the Utirik and unexposed populations a low incidence of thyroid nodules was found, and these occurred onlyin the older age group. In view of the potential seriousness of the thyroid abnormalities in the Marshallese, it was de- cided that the exposed people should receive thyroid hormonetreatment for the remainderof their lives in order to suppress TSH secretion. Such treatment might prevent further development of nodules and possibly induce regression of existing nodules. The treatment might also stimulate growth in retarded children. Accordingly, at the time of the September 1965 survey, the 55 people in the more heavily exposed group were started on Lthyroxine at a daily dose of 0.3 mg to all people <50 years of age and 0.2 mg to all people >50. The new cases with thyroid nodules wereleft in the Islands under hormone treatment, with the idea that, if at the time of the next survey (March 1966) the nodules had not regressed or further nodules had developed, consideration would be given to bringing them to the United States for study and possible surgery. In March 1960 it was United States. These cases had not shown reducbeen on the hormone therapy for the 6-month period. Four children with thyroid nodules who were not considered to have had an adequatetrial therapy with thyroid hormone were left in the Islands to be re-evaluated later. In one 40-year-old man a nodule had disappeared, presumably as a result of therapy. Surgical Cases Of the 16 cases with nodules, a total of 11 have had surgery. In 1964, the first 3 cases in teen-age girls were operated upon® at the U.S. Naval Hospital, Guam.'*** In July 1965, 3 cases were brought to the Medical Research Center at Brookhaven National Laboratory (Figure 22) and later taken to the New England Baptist Hospital, Boston, for surgery.** In May 1966, 5 additional cases were brought to Brookhavenfor further examinations (Figure 23) and werelater taken to the New England Deaconess Hospital in Boston for surgery.** At Brookhaven, detailed thyroid studies were carried out, including '**I and **"Tc uptake studies and scans before and after TSH administrationt and measurement of basal metabolism rate, serum protein-boundiodine, serum thyroxine (7,) level, and serum antithyroglobulin antibodytiter. Brief hospital summaryreports on these cases are presented in Appendix 6. Gross Appearance. In all 9 children operated upon, the glands were found at surgery to be multinodular, although in somecases the nodules had appearedclinically to be solitary. The nodules varied in diameter from a few mm to several cm, in consistency from fluctuant to relatively hard, and in color from pale grey to pink or red. Cyst formation was present in many, and some had hemorrhagic areas. Figure 24 showsthe gross appearance in some cases with benign nodulesat surgery. In one adult (No. 59), there was a solitary nodule, and the surrounding tissue appeared normal. In the other adult (No. 64), the gland also did not show multiple nodularity, but contained two firm, yellow, malignant nodules about | cm in diameter (Figure 26). *Surgery was performed by Captain C.A. Broaddus, MC. USN **Surgery was performed by Dr BP. Colcock of the Lahey Chic tWe are grateful to Dr. H.L. Atkins for these analyses