4 lated directly to radiation effects during thefirst few years post exposure. No prophylactic or spe- cific therapy for radiation effects was ever considered necessary or given. Epidemics of chicken pox and measles that occurred during the first year showedno greater incidence or severity in the exposed than in theunexposed Marshalles people. During the first months post exposure about % of the exposed people exhibited loss of weight of several pounds. This may possibly have been related to their radiation exposure, althoughit was difficult to rule out possible effects due to changeof environment. At 3 years post exposure the immune response to primary and secondary tetanus antitoxin was tested and foundnotto be significantly different in the exposed compared with the unexposed populations. There were 10 deaths in the exposed populations over the 10-year period (see Table 6). Of these, 2 deaths were recorded as due to malignancies. The 10 deaths that have occurred in the exposed population represent a mortality rate of 12.2 per 1000 population per annum, compared with 8.3 for the Marshall Islands as a whole (1960). The somewhat higher death rate in the exposed group is partly offset by the higher proportion of older people; those >65 years of age were originally 20% in the exposed group and only 7% in the unexposed group. Growth and development studies on the children (height, weight, anthropometric measurements, and radiographic studies for bone age) have revealed slight retardation in growth and developmentin the boys exposed on Rongelap who were <12 years of age at the time of exposure, particularly those 12 to 18 months of age at exposure. Onlyslight immaturity was noted in the female children of this group. In studies of children born of exposed parent(s), it was noted that males showeda slight growth retardation andslightly lower levels of peripheral blood elements compared with male children of unexposed parents; however,this latter finding has not been evident since 1963. Theslight growth difference does not appearto justify a conclusion that there is an as- sociation with exposure of the parent. It was difficult to evaluate the effects onfertility. However, a review ofthe dzrth rate of the exposed groups overthe past 10 years seemsto indicate no noticeable effects of their exposure on fertility. The 30 births represent a rate of 61 per 1000 population per annum comparedwith 37.3 for the Mar- shall Islands (1957). The incidence of miscarnages andstillbirths in these exposed women was about twice that in the unexposed women during the first 4 years after exposure, but no difference has been noted since then (see Table 8). A cardiovascular survey of the adults (1959) showed no outstanding differences between the exposed and unexposed groups. The Marshallese people appearedto have less hypertension on the whole than is noted in people in the continental United States. Anarthritis survey (1959)" showed nogreatdifferences between the exposed and the unexposed people, and about the sameincidence as is seen in American populations. Ophthalmological surveys showed no remarkable differences between the exposed and unexposed groups exceptpossibly slightly greater numberof cases of pterygia, pingueculae, and corneal scars in the exposed groups. It is not known whether these findings are of anysignificancein relation to their radiation exposure. Slit-lamp observations showednoopacities of the lens characteristic of radiation exposure. As a whole, visual and accom- modation levels in the Marshallese appeared to be above the average in the U.S. population. Dental surveys’ showed nosignificant differences in caries rate between exposed and unexposed groups. However, the incidence and severity of peridontal disease wasslightly greater in the exposed group. It is not known whetheror not this finding is related to radiation effects. The poor oral hygiene generally observed in the Marshallese hadits usual results, namely, high caries rate in teen-age children, severe peridontal lesions in adults (heavy calculus andloss of alveolar bone), and edentulous mouthsin the aged. Radiation exposure did not appear to have affected developing dentition in the exposed children. Aging studies were done in which various parameters usually associated with aging were measured or estimated on a 0 to 4 + scale (skin looseness, elasticity, and senile changes; graying of the hair and balding; accommodation, visual acuity, and arcus senilis; hearing; cardiovascular changesincluding blood pressure and degrees of peripheral and retinal arteriosclerosis; neuromuscular func- tion; and hand strength). Comparison of these measurements in exposed and unexposed individ-