few grey hairs; +-+ = moderate gray hairs, and +++ = almost completely gray. Results Estimate of age. The nurse’s observation simply provided an estimated age of the subject—based on physical appearance—for comparison with his actual chronologic age. The subjects came throughtheclinic, of course, without the observer knowing their exposure histories. Ages of 1,304 subjects were estimated. The size of the sample according to exposure group and the mean differences between estimated and actual ages are shownin table |. It can be seen that the nurse systematically overestimated the age of male subjects, and only slightly underestimated the age of females. Estimates were more exact for females; 95 per cent confidence limits on the difference (actual—estimated) were —4.7 to +5.1 years for females and —7.2 to 4.5.8 for males. These individual differences were too slight to affect the validity of the comparisons of the radiation exposure groups. The relationship to exposure status was studied by comparing the mean differences for exposure groups. Also studied was a regression analysis of the age differences and distance of survivors from the hypocenter (combining both groups I and 2). The differences noted in both analyses were well within the usual range of chance variation, so that a) k Po. ee ‘sare Ca CJ7=4 GERIATRICS, JANUARY 1961 wtem Tian, Sie. wou Time, SEC, D x» | sour 2 | I I fd scale. While the subject was lying down for his routine electrocardiogram, the nurse inspected the temple areas for gray hairs. The choice of site and the scoring method were based on the findings of Terada,® who studied hair graying in Japanese subjects very carefully with more quantitative methods. In the scoring system, 0 = no gray hair; + = aque AGE OT CEAMIRATION Fig. m1. Mean time for skin to flatten completely, by age and exposure group. it could not be concluded from these data that the irradiated subjects looked any older than the nonirradiated subjects. Skin retractility. This determination was performed on 196 males and 413 females—a total of 609. The test measured the time in seconds required for a standard “pinch” to flatten completely. The test showed good correlation with age, but differences were more marked in the older age group. The correlation ratio was .66 for the total sample, which indicates that approximately 43 per cent of the total] variation was accounted for by age alone. Since no sex differences were detected, both sexes were combined for exposure group comparisons. Figure III shows the mean retractility time of the 4 exposure groups. It is evident that the exposure groups were quite homogeneous. An analysis of variance failed to suggest any relationship betweenskin retractility and irradiation. Skin looseness. This test proved of relatively little value except in the younger age groups. During springrelease closure, the pincers were able to catch a skin fold on the forearm in virtually 100 per cent of subjects beyond the age of 30. Table 3 shows the percentages by age and exposure group for both sexes combined. Again, no rejationship to radiation exposure was detected in this technically unsatisfactory test. 31