-18- those cases with thyroid nodules, 2 boys with greatestgrowth retardation developed atrophy of the thyroid gland with signs of hypothyroidism(Fig. 21). Figure 22 shows the gross appearance of the nodules at surgery. Note the varied size of the nodules from several millimeters to several centimeters, some being cystic, and some hemorrhagic. Figure 23 shows the microscopic characteristics of these benign nodules. They resemble closely adenomatous goiter usually seen with iodine deficiency and definite radiation effects were not identified in the glands by most pathologists. Figure 24 shows the gross and Figure 25 the microscopic appearance of the mixed papillary and follicular cancer with. localized metastases that occurred in the woman referred to above. It has become increasingly clear that the growth retardation noted in the children is probably associated with thyroid deficiency, even though a hypothyroid tendency was not detected in earlier years when the growth retardation was first noted. It has since been discovered that a high level of iodoprotein is normally present in the Marshallese people which gives a falsely high PBI level (Rall and Conard). low degree of hormone deficiency. This may have masked a However by 11 years after exposure the 2 boys showing the greatest growth retardation developed characteristics of frank hypothyroidism with atrophy of the thyroid gland, drop in PBI level to less than 2 yg%, development of coarse facial features, dry skin and Achilles reflex with sluggish return and bone dysgenesis. TSH levels indicated a primary hypothyroidism. High pituitary Several other children with less degree of growth retardation have recently shown some degree of thyroid deficiency also. 5001319