12 Impairmentof hearing was averagedfor the two ears as follows: the decibel loss for each of seven frequencies (200, 500, 1000, 2000, 3000, 4000, and 7000) in each ear was averaged to give a mean frequency loss in decibels for the twoears. Cardiovascular Changes. 1. Systolic and dias- tolic blood pressures were obtained with the stand- ard aeronoid cuff-type sphygmomanometer. Two readings were obtained, and the average value was used. There was no basic or adjusted level of physical activity such as resting for a standard period prior to the readings. Pressures were taken on the left arm with the subject supine during the course of the physical examination. 2. The degrees of peripheral arteriosclerosis and retinal artertosclerosts were scored on a 0 to 4+ scale. The former was estimated by palpation of the peripheralarteries, the latter by viewing the retina with an ophthalmoscope. Neuromuscular Function. Neuromuscular function was measured by having the subject depress the key of a hand tally type of blood cell counter as many timesas possible in the period of one min- ute. The total number of depressions represented the score. Hand Strength. Handstrength was measured by a Smedley hand dynamometer.* Thespring tension of the hand grip was measuredin kilograms. The maximum squeezestrength in the dominanthand in three tries was recorded. Handling of Data. Because of sex differences, some of the above criteria were evaluated sepa- rately for the two sexes; these were baldness, neuro- muscular function, and hand strength. In order that the estimated and measured data could be compared and combined,both types of data were converted to a percentage scale. The estimated values 0,1+,2+,3+,and 4+ were presented also as 0, 25, 50, 75, and 100%, respectively. In the case of the measured data, the values associ- ated with least aging were taken as zero percent (sometimes the highest reading, as with hand strength; sometimes the lowest, as with hearing loss), and those indicating most aging as 100%. ‘The data were examined on both anindividual basis and a population basis. A mean agescore was obtained for each individual by averagingall his percent test values. In studying population trends, means were calculated for each criterion by 5-year age groups (in most cases) including *C.H. Stoelting Company, Chicago,I). S60 TST combined exposed and unexposed populations; these were plotted, and a curve was drawnaccording to the best fit by eye. A curve was obtained in the same way of the 5-year group meansofthe individual mean age scores. The combining of scores into 5-year age groups was done to reduce possible errors due to the uncertainty of the exact age of some individuals. Laboratory Procedures Hematological Examinations. “Iwo complete routine blood counts were done, about a week apart, and a third was done on persons showing abnormalities. White blood counts, red blood counts, and Price-Jones curves (for determination of red cell size distribution) were obtained with ‘the electronic Coulter, which proved very satisfactory and time-saving for this type of field examina-_ tion. Differential counts were performed in the usual mannerafter staining with Wright’s fluid. Platelet counts were done by phase microscopy, and hemoglobin was determined by the cyanhemoglobin technique with the Lumitron colorimeter. Serum proteins were determined with the Hitachi refractometer. Blood and serum samples for the studies described below were collected in the field, kept underrefrigeration, and shipped by air to the various laboratories in the United States for analysis. Urine Analyses. Routine urine analyses were carried out on all people receiving physical examinations. These included determinations of protein and hyperglucosuria by reagent paperstrips.* In all cases showing positive findings, the urine wascentrifuged and the sediment examined microscopically. In the four cases showing positive urine sugartests, fasting blood specimens were obtained and analyzed for blood sugar at the Naval Dispensary on Kwajalein. Serum Cholesterol. Serum cholesterol was determined in blood samples drawn from exposed and unexposed Rongelap people, and also in about 70 blood samples from people at Utirik Island and 63 from people at Majuro Atoll. These analyses were done at the National Institutes of Health by Dr. J.H. Bragdon and Mr. J.C. Lauter. ComplementFixation Tests. Serum samples obtained from 163 exposed and unexposed Rongelap people were frozen and sent to the Nationa! Insti- tutes of Health for various examinations. Com*Clinistix, Ames Company, Inc., Elkhart, Indiana.