30 malignancies is well documented,52°55 but that with otherless well-defined aging criteria is not clearcut. Beebeet al.,35 reporting on 1300 deaths from 1950 to 1966 among 8200 exposed Japanese, stated: “Once cancer is removed from thelist of natural causes, mortality appears to bear no relation to radiation dosage. In none of the 4 time periods is there evidence of general increase in mortality that one might expect from the hypothesis of accelerated aging.”’ Since the underlying mechanisms of ordinary aging are notclearly defined, it is difficult to compare radiation effects with the aging process and to recognize their interaction. Studies of longevity in the relatively small Marshallese population underobservation do not provide any evidence of a possiblelife-shortening effect of radiation. At this time the average age at death in the Rongelap exposed group1s 64 years compared with 65 in the un- exposed population, and 61 among the unexposed Utink people. The differences are not significant. Numerous empirical studies concerned with possible radiation-induced aging effects have been carried out on the Japanese survivors52-56 and on the Marshallese.3-12.13.57-61 Qn several occasions Rongelap people were given a battery of nonspecific tests for aging similar to those used in the Japanese studies.3-+2:13 Some of these tests were based on subjective assessment, on a 0 to 4+ scale, of items such as greyness of hair, arcus senilis, senile changes in theskin,balding, etc., but most involved direct measurements of items such as skin looseness, skin elasticity (skin caliper), visual accommodation, visual acuity, hearing (audiometric), blood pressure, neuromuscular function (light ex- tinction test), hand strength (dynamometer), vibra- tory sense (vibrometer), and lean body mass (whole-body potassium by gammaspectrographic analysis). Comparison of these values in the exposed and unexposed Marshallese (Table 17) showed nosignificant differences. The biological age scores (average percent score), plotted in Figure 23 for both groups, are about the same. 5. Immunological Studies Radiation is known to impair the immunological status of individuals soon after exposureif the dose is sufficient to producesignificant leukopenia. During the early period, though the acute effects on the Rongelap people included considerable de- pression of peripheral blood elements, comparison of the incidenceof infections with that in the Uurik group gave no evidence of impaired immunity. Reduced immunological reserve may likely be a late effect of radiation exposure,®? butit has not been observed conclusively in man. The development of leukemia and other malignancies following exposure may quite possibly be related to re- Table 17 Correlation of Criteria With Age and Radiation Exposure” Correlation with age (r value) Grayness 0.87 +17.0 Significance* ( p) N.S. (0.70) 0.83 0.81 0.74 0.70 0.0 —14.1 + 7.3 + 1.6 N.S. N.S. N.S. N.S. (1.00) (0.11) (0.68) (0.82) Visual acuicy Hearing loss Hand grip (M+ F) Reaction time (M + F) (light extinction test) 0.69 0.67 0.67** 0.64"* +14.0 + 79 + 13.8 (M), + 13.8 (F) — 2.0(M), —10.5(F) N.S. N.S. N.S. N.S. (0.59) (0.40) (0.15, 0.18) (0.88, 0.55) Potassium (M + F) Cholesterol Neuromuscular function (M + F) (handtaily) 0.41°* 0.39 0.36"* Systolic blood pressure Combined scoret °N.S. - not significant at 5% level. 2006121 Percent Arcus senilis Accommodation Skin retraction Skin looseness Vibratory sense (M+F) - Correlation with radiation 0.70** ~ 1.4(M), +24.6(F) N.S. (0.90, 0.20) 0.55 — 11.5 — 14.6 (M), + 10.6 (F) —17.2 + 3.2(M), +1.1 (F) N.S. (0.17, 0.22) N.S. (0.05) N.S. (0.85, 0.95) 0.99 + 7.0 N.S. (0.27) **r values for males and females averaged. N.S. (0.30) Weighted accordingto r value.