Incidence of Humans After Malignant Thyroid Tumors In Diagnostic Doses of lodlne-131. Exposure to Thyroid Gland Versus Observed II. Estimation of Size, Thyroid Radiation Number of Malignant Dose, and Predicted

ABSTRACT-The size of the thyroid glands was analyzed for 10 % of the patients in a selected group that had been exposed to diagnostic doses of 1311. The mean thyroid gland weight ± SO was 50±33 g for patients 20 or more years of age and 10±5 g for patients less than 20 years of age. With the present follow-up, diagnostic doses of 131 I appeared not to be associated with an increased risk for later development of malignant thyroid tumors. Possible reasons for the difference between the observed number of such tumors and the number expected (47-124) on the basis of risk estimates of the United Nations Scientific Committee on the Effects of Atomic Radiation are discussed.-JNCI 65: 1221-1224, 1980. In a retrospective study (1) the incidence of malig-nant thyroid tumors in 10,133 patients who had received diagnostic doses of 131 I between 1952 and 196