4 1. Excised thyroid showing nodular nature of gland. perts advised that the people be given supplemental thyroid hormone. This treatment was instituted in September 1965. The Table outlines the incidence of benign nodules (including atrophy of the gland), the malignant lesions, and the estimated dose of radiation to the thyroid glands in the various populations understudy. The highest incidence of thyroid lesions (89.593) has been noted in the heavily exposed Rongelap children who were less than 10 years of age at the time of the accident. The absence of lesions in children of the same ave in the lesser ex- posed and unexposed groups is most notable. The incidence of thy- roid lesions in the adults of the 318 re. | 2. Autoradiogram of section made through nodule of thyroid with benign lesions. Lack of grains (superimposed blackening) shows adenomain center is nonfunctioning (hematoxylin-eosin stain, x14). more heavily exposed group is considerably lower than in the children but is significantly higher than is generally seen in the adult popula- tion of the lesser or unexposed groups. (Only one individual has been found to have an adenomatous thyroid lesion in the lesser-exposed Rongelap group. ) Thefirst case of carcinoma of the thyroid was discovered in 1965 in a 40-year-old woman in the heavily exposed group, 11 years after ex- posure. At that time the relationship of radiation exposure to the appearance of this lesion was seri- ously questioned, although such lesions are rare in the Marshallese. However, in September 1969 sur- gical exploration of the thyroid on JAMA, Oct 12, 1970 @ Vol 214, No 2 2012008 a te a five Marshallese with palpable nodules revealed malignant lesions in three additional people. Two of the malignant lesions occurred in women in the more heavily exposed Rongelap group, one in a 36-yearold woman who was 21 years of age at exposure and one in a 22-yearold woman who was 7 years of age atthe time of exposure. This latter patient presents the first malignant thyroid lesion to be noted in the group of heavily exposed children who have the highest incidence of benign lesions. These recent find- ings greatly increase the concern about radiation-induced neoplasms in this population. The fourth malignantlesion was noted in a woman from Utirik Island. Thyroid Neoplasia—Conard et al