associated with thyroid injury in some of the children, have been discussed in detail in this report. The greatest incidence of these abnormalities has been in the higher-dose Rongelap group, particularly in children exposed at <10 years of age, with less incidence in the Ailingnae group and least incidence in the lower-dose Utirik group. The recent development of thyroid nodules in two Rongelap males exposed in utero indicates that radioiodines may be passed from mother to fetus. ~~ Almost all patients, including those in the unexposed group with thyroid nodules, have had thyroid surgery in U.S. hospitals. A wide spectrum of lesions has been found. Thyroid hypofunction, not related to thyroidectomy, was first noted in two Rongelap boys who developed frank hypothyroidism with growth retardation. Biochemical (subclinical) hypothyroidism has been noted in some prior to thyroid surgery for nodule removal. More recently, about 6 adults (5 Rongelap, 1 Ailingnae), who received lower doses than the children and showed no detectable thyroid nodularity, have developed biochemical hypothyroidism. No hypo- function of the thyroid has been detected in the exposed Utirik population. C. Comments From the Marshallese experience it is clear that in any future accident involving radioiodines the use of oral stable iodine to suppress radioiodine uptake by the thyroid, particularly in children and pregnant women, should be considered (249). To ascertain the degree of radioiodine absorption, it would be helpful to have direct instrument readings over the thyroid, with leg or arm readings as a control; also, urine levels of radioiodine would be helpful. With regard to late effects in persons receiving significant radiation doses to the whole body or thyroid, regular follow~up examinations should be done over the ensuing years with particular attention to hematological status, development of cancer, and thyroid abnormalities. Even though the prophylac- tic value of thyroid hormone treatment in preventing development of thyroid abnormalities has not been proved in the Marshallese or other humans, such treatment is sound and should be considered. During follow-up thyroid examinations, determination of serum TSH levels would be desirable, since the Marshallese experience has shown this test to be a most sensitive indication of reduced thyroid function. In addition, thyroid uptake studies of radioLodine and scans of the gland should be considered. Any distinct thyroid nodules should be surgically removed. If thyroxin treatment is not already a part of the treatment regimen, it should be instituted in surgical cases as well as any cases showing deficiency of thyroid function. Patients who have had malignant lesions removed should of course have regular follow-up examinations. Although the later development of thyroid malignancy is a serious prob- lem, the consequences are not as likely to be fatal as those of other types of malignancies. With the medical and surgical treatmenc of thyroid disease now available, death associated with malignant tumors of the thyroid is unlikely except in the case of the most malignant types, which appear to be rare in irradiated groups. As has been pointed out, the uncertainty of dose estimates in the Marshallese has hampered evaluation of dose-response relationships, - 87 -