45 Correlation of Data. each light as it appeared. The total time necessary to extinguish all the lights was measured. Thistest In order to placeall the data on a commonbasis for comparison and combination, the data were converted to a percentage involved both manual dexterity and mental reaction time’? (see Figure 33). (4) Hand Strength. The basis for each criterion. In the case of the measured data, values associated with least aging were taken as 0% (sometimes the highest reading, as with handstrength; sometimes the lowest, as with spring tension of the hand grip was measured in kilograms with a Smedly hand dynamometer.* The maximunrsqueezestrength in the dominant handin 3 tries was recorded. Miscellaneous Tests. (1) Body Potassium Levels hearing loss), and conversely the values showing (*°K). Since loss of muscle mass occurs with aging and total body potassium is closely related to muscle mass, it has been shownthat bodylevels of potassium decrease with age.’*:"* Whole-body spectrographic analyses were carried out in the Marshallese in a lead-shielded structure. In this way “°K levels were obtained and presented as K/kg body weight. The accuracy of these data could have been improved by obtaining moreprecise determinationsof lean body mass, such as by measurement of body water."* The valueslisted are averages of the 1961 and 1965 determinations. (2) Blood Serum Cholesterol Levels, These were ob- tained in 1957 onsera sent to the United States.** *S.H. Stoelting Co., Chicago,Ill. **The analyses were done at the National Institutes of Health by Dr. J.H. Bragdon and Mr. J.C. Lauter. most aging were taken as 100%. The estimated cri- teria with values of 0, 1+,2+,3+,and4+ were presented as 0, 25, 50, 75, and 100%, respectively. The data were examined on an individua! basis as well as on a population basis, and comparisons were madelargely by using means for each decade age group. Except where indicated, the data used were collected during the |1- and 12-year survevs, An analysis of variance was used to determine differences amongthefactors of sex, age, and radiation levels.* These data were programmed and analyzed on a high speed digital computer. ** For each criterion, the combined score over sex and radiation level was correlated with age. A curve of *Mr. Keith Thompson of Brookhaven National Laboratorv did the statistical analyses of these data. **The Control Data Corporation 6600, at Brookhaven National Laboratory. Table 22 Correlation of Criteria With Age and Radiation Exposure Correlation with age Correlation with radiation (r value) Percent Grayness Arcussenilis Accommodation Skin retraction Skin looseness Vibratory sense (M + F) 0.87 0.83 0.81 0.74 0.70 0.70** +17.0 0.0 —14.1 + 7.3 + 1.6 — 1.4(M), + 24.6(F) Hearing loss 0.67 + 7.9 Visual acuity 0.69 Hand grip (M+F) Reaction time (M + F) (light extinction test) Systolic blood pressure Potassium (M + F) Cholesterol Neuromuscularfunction (M + F) (handtally) Combined scoret *N.S. — not significant at 5% level. Significance* ( p) + 14.0 0.67** 0.64** 0.55 0.41** 0.39 0.36** +13.8(M), — 2.0(M), —1i5 —14.6(M), —17.2 + 3.2(M), 0.99 + 7.0 **r values for males and females averaged. + 13.8(F) —10.5(F) + 10.6(F) + 1L.1(F) N.S. N.S. NLS. N.S. N.S. N.S. (0.70) (1.00) (0.11) (0.68) (0.82) (0.90, 0.20) N.S. (0.59) N.S. (0.40) N.S. N.S. N.S. N.S. N.S. N.S. (0.15, 0 (0.88, 0.55) (0.30) (0.17, 0.22) (0.05) (0.85, 0.95) N.S. (0.27) tWeighted according to 7 value.