distant metastases, highly favorable. the clinical prognoses for these indiviauals remains Although fourteen of these tumors were classified morpho- logically as malignant neoplasms (carcinomas), either occult or overt, it should be emphasized that the lay term “cancer,” with its ominous implications, should not be applied to such clinically benign lesions, a point ell noted by others (255,259). 2. Thyroidal Aypofunction Criteria used in defining biochemical thyroid function were developed from findings in the concrol and exposed Utirik populations presented in Table 6.* In the initial series, an upper limi: of 3 WW TSH/ml serum was selected, since baseline studies in 25 unexposed Marshallese who were clinically and biochemically euthyroid yielded a mean value of 2.0 w0/ml (SD = 0.73) with a range of 0.5 to 3.0 w/ml. Serum TSH concentrations in this grouo after injec~ tion with 500 tig of TRH averaged 11.5 wU/ml (SD = 4.5) with a range of 4.7 to 20.0 pU/ml. These results are similar to those obtained in other normal populations with respect to both basal TSH and TRH-induced TSH release (111,130,131). Table 6. Number of subjects with elevated serum TSH concentrations in cortrol and exposed Marshallese populations (1975-1579). Initial Series Sub jects Control (unexposed Marshallese) Utirik exposed (thyroid dose <95 rads) Rongelap-Ailingnae exposed (No prior surgery) Tested once Single TSH >3 uU/ml Second Series Tested two or more times 115 rl (102) 67 99 12 (12%) 101 43 ll (262) 36 Two TSH values >6 WU/m1 2 (3.0%) 0 7 (192%) As shown in Table 6, only 10% of a control population of 115 had serum TSH concentrations >3 pU/ml. In the the Utirik population: exposed to relatively low doses of radioiodine, 12% had single TSH values >3 wW/ml. These results suggested that there was no difference between these two populations with respect to the prevalence of elevated serum TSH. In the exposed (but associated with the low doses to their thyroids. - 70 - ——e *Data from the exposed Utirik group were combined with the data from the unexposed group because that group showed no evidence of thyroid hypofunction