32 The various changes generally associated with physiological senescence are known to show wide variability among individuals of the same age, and this was borne out by these data. However, some of the criteria appearedto be better indices of aging than others, judging by the degree of change and the variability of the data observed. (This statement is not based on statistical analysis.) Someof the better criteria appeared to be accom- modation of the eyes, visual acuity, skin retraction, arcus senilis, greying of the hair, and hand strength. The measured criteria would be ex- pected to be morereliable than the estimated ones in view of the subjective element andless precise Table 20 Residual Beta Burns, 1960 Subject No. Sex 17 F 24 F 26 39 M F Age Description 9 Shght depigmentedscars, left ante- cubital fossae. 19 Mottled spots of pigmentation and depigmentation, dorsum offeet. 18 Markedscarring between first and secondtoes, right foot, with binding to subcutaneoustissues. Areas oflesser involvement peripheral to this area. No evidence of chronic radiation dermatitis. 20 Slight mottled pigmentation-depigmentation with little scarring, dor- 49 F 39 F 63 F 67 F 78 F sum of feet. Mottled hyperpigmented spots persist on back of neck. 21 Black moles believed to have increased in numberoverright side of neck, also several noted in left antecubital fossa. 40 Mottled roughening and pigment variation, back of neck. scoring of the latter. This appeared generally to be the case, but the estimated values for greying of the hair and arcussenilis correlated surprisingly well with age. The amountof subcutaneousfat probably influenced measurementsof skin looseness, but, since loss of subcutaneousfat is some- what age dependent, probably in the right direction. It is hoped thatin the futurestatistical treatmentofthe data mayfurnish a weightingfactorfor each criterion based on the degree of age-associated change andthevariability of the data. It is not alwayspossible to run the complete battery of tests on each individual, and use of such weighting factors would tend to minimize the disparity due to the omissions. The data presented must be consideredaspreliminary in nature and to represent only a small fraction of the many varied changes associated with the aging process, Underthe conditions of examinations of the Marshallese, the battery of tests employed is necessarily limited. As more experience is gained, someof the tests may be eliminated and new ones added. Thetests of vigor are thought to be extremely importantin assessing aging, andit is hoped that moretests of this nature may be added. Atthis time the data are presented to introduce an approach to a feasible means of assaying “biological age” which might be ofuse in studying the possible effects of radiation on the ag- ing phenomenonin humanbeings. In the case of the exposed Marshallese, results of further aging surveyswill be carefully evaluated, andthe results 42 Mottled pigmentation, left side of neck, with slight roughening of skin. 20 Depigmented scarred areas with slight atrophy of skin over dorsum of feet, particularly at site of deeper scar on left foot. Some areas adjacent to scars show increased pigmentation. 43 Pigmented moles appear to have increased in numberover left side of neck and to lesser extent on right side at sites of rather deep beta 79 M burns. 45 Back of left ear shows depigmented scar with some binding downto cartilage. No evidence of breakdown. Figure 32. Residual scarring between first and second toes, right foot, from beta burns, 5 years post exposure (Subject #26).