-2During the ensuing decade the people remained as healthy as the population of unexposed Rongelap people used as a control group (about 200) with no further evidence of radiation effects, except an increase in miscarriages and stillbirths in exposed women which is questionably related to exposure. II. Late Effects A. Studies with negative findings Animal studies have shown some nonspecific late effects such as accelerated aging and premature deaths from degenerative diseases. Such effects have not been detected in human exposures. Radiation-induced shortening of life span appears to be related entirely in human beings to certain malignancies. In the Marshallese numerous studies of premature aging effects, similar to those carried out in the Japanese, have not re- vealed evidence for such effects. There has been no indication thus far of any increase in degenerative diseases among the exposed Marshallese or Japanese. Similarly, though genetic defects in offspring of irradiated animals have been demonstrated, such defects have not been positively identified in studies of the first generation children of the Japanese. In view of the negative nature of the Japanese findings no organized genetic studies of the Marshallese children have been carried out, though no apparent effects have been noted in the newborn, most of whom have been examined. Dr. J. Neel (Univ. of Michigan) has examined, with negative results, a limited number of blood samples of children of exposed Marshallese for variants of serum proteins and erythrocyte enzymes that might indicate genetic mutations. B. Possible radiation late effects in the exposed Marshallese i. Thyroid (a) Growth retardation, development of nodules Between 5-10 years after exposure growth retardation in several of the children exposed at less than 5 years of age (particularly notable in two boys exposed at 1 year of age) was the first evidence of thyroid injury. Thyroid nodularity first began to appear at 9 years after exposure in the Rongelap people and shortly thereafter in the Ailingnae group and more recently in the Utirik population. The accompanying table shows the present status of the thyroid findings, including the results of surgery. There have now been 45 thyroid abnormalities (34 with surgery) among the 244 exposed Marshallese (39% of the Rongelap people and 7.0% of the Utirik people compared with about 5% in unexposed Marshallese). The occurrence of three thyroid cancers in the exposed Utirik population (compared with four in the Rongelap group) appears to implicate radiation exposure in the etiology but the high incidence is puzzling since it is greater than would be predicted based on Rongelap and Japanese data, and there does not appear to be any increase in benign thyroid tumors in the group compared to the much greater prevalance in the Rongelap group. The institution of hormone treatment (Synthroid) in all exposed Rongelap people, which began in 1965, has been essential in maintaining a euthyroid state in the operated cases and has been important in correcting growth rg sULGT43