effects related to internal absorption of radionuclides). The low dose Utirik group showed only statistically a slight depression in platelets without clinical signs of exposure. There were no deaths associated with the acute exposure of the Marshallese and, except for the skin burns, no treatment was necessary. Blood levels returned to near normal by one year and beta burns healed: and hair regrew within a year with only a mild scarring and residua in about 15 people. During the ensuing 9-10 years the people appeared as healthy as the population of unexposed Rongelap people used as a control group (about 200) with no further evidence of radiation effects, except possibly an increase in miscarriages and stillbirths in exposed women. At 10 years chromosome studies showed residual evidence of exposure in some people in the form of slightly elevated numbers of aberrations. Late Effects The only diseases that have been positively identified in man as late effects of radiation exposure are benign and malignant tumors. OfE these, -leukemias Cexcept cn)and thyroid tumors have been the principal ones. c ba ae wewe pow Ler ey Pe Cees es ae <i: 1 Yadfation exposure-havebegun-tozappear:—-These. Seancers’ of”‘the breast, lungs, and stomaeh; and other gastrointestinal tumors. In the case of the Marshallese, numerous thyroid tumors have developed (see below) and possibly associated with radiation exposure has been one fatal case of acute leukemia and GUS"Seeen-SeStewancer-ef=the-stomzch. 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 exposed human beings. In the Marshallese numerous studies for premature aging effects, similar to those carried out in the Japanese, have not revealed 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 of the Japanese. In view of the negative nature of the Japanese findings no comprehensive genetic studies of the Marshallese children have been carried out. 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. These studies will be extended. It should be pointed out that the Marshallese worry a great deal about possible genetic effects in their children and have not readily accepted our explanation for the lack of inclusion of children in such studies. With the expanded medical program, begun last year, examination of children on Rongelap and Utirik may help satisfy their desires in this regard. However, lack of inclusion of the children for the hospitalization benefits of PL 5-52 (Fallout Survivorts Act) continues to be resented by the people. Lo. 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. Enclosure III shows the present status of the thyroid qe findings, including surgery. The institution of hormone treatment (Synthroid) in all exposed Rongelap people, which began in 1965, has been essential in