- 346 - the inhabitants absorbed radionuclides in the fall-out by inhalation and ingestion of contaminated food and drinking water. Based on radiochemical analyses of pooled urine samples taken several weeks after the accident, it was estimated that the adult thyroid gland received about 160 rads from the radioiodines, in addition to 175 rads from the external gamma radiation. In view of the smaller thyroid glands of the younger children, it was estimated that they received in the range of 700-1400 rads in the more heavily exposed group. As of March, 1966, a total of 16 cases of nodules of the thyroid gland and two cases of hypothyroidism had been detected. The largest incidence(79%) has occurred in the children exposed at less than 10 years of age. No such pathological change has been noted in unexposed children or children in the lesser exposed groups. Thyroid surgery has been performed on 11 cases with nodules, Ten of these cases, 9 children and one adult, were all found to have benign nodules. One 41 year old woman was found to have a cancer of the thyroid, Description of these thyroid lesions as well as the possible radiation etiology has been discussed in a recent paper (Conard, Rall and Sutow 1966), A general review of the findings in the Marshallese can be found in other references (Cronkite, Bond, Conard, Shulman, Farr, Cohn, Dunham and Browning 1955, Conard and Hicking 1965). There are few other so-called late effects of radiation which can, with reasonable certainty, be ascribed to exposure in these people. Among these was an increased incidence of miscarriages and stillbirths noted among the exposed women during the first four years after exposure; lag in complete recovery of peripheral white blood cells and platelets to levels of the non- exposed comparison population; and slight retardation of growth and develop- ment of children, particularly boys exposed at less than five years of age, A hypothyroid etiology for growth retardation is strongly suggested by the recent findings of definite hypothyroidism in two of the most retarded boys in the Group (Conard et al. 1966; Sutow, Conard and Griffith 1965), General health and fertility have been about the same in the exposed as in the comparison population, The mortality rate has been somewhat higher in the exposed population but this population has a larger percentage of older people. Possible life-shortening effects of radiation can be best evaluated in the future, This report concerns an attempt to evaluate possible effects of radiation on the ageing process in the exposed population. During physical examinations ageing effects are usually referred to in a general qualitative sense. In order better to evaluate possible ageing effects, a more quantitative approach was indicated. There are a large number of criteria which have at one time or another been regarded as being age dependent. These studies represent an effort to select criteria which could be carried out under conditions of these examinations. The overall objective has been to combine the scores of the various criteria into one "average age score" for each '