12 Impairment oPRé@aring was averaged for the two ears as followsiihedecibel loss for each of seven frequencies (200, 500, 1000, 2000, 3000, 4000, and 7000) in each ear was averaged to give a mean frequencyloss in decibels for the twoears. Cardiovascular Changes. |. Svstolic and diastog bloodpressures were obtained with the standard aeronoid cuff-type sphyygmomanometer, 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 ofperipaeralarteriosclerosis and retinal arteriosclerosis were scored on a0 to ++ scale. The former was estimated by palpation of the peripheral arteries, the latter by viewing the retina with an ophthalmoscope. Neuromuscular Function. Neuromuscular func- tion 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 minute. The total number of depressions represented the score. Hand Strength. Handstrength was measured by a Smedley hand dynamometer.* The spring tension of the hand grip was measured in kilograms. The maximum squeeze strength in the dominant hand in three tries was recorded. Handling of Data. Because of sex differences, some of the above criteria were evaluated separately for the two sexes; these were baldness, neuromuscular 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 pre- sented also as 0, 25, 50, 75, and 100%, respectively. In the case of the measured data, the values associated 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 an individual basis and a population basis. A mean age score 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, Ill. combinea exposed and unexposed populations: these were plotted, and a curve was drawn according to the best fit bv eye. A curve was obtained in the same way. of the 5-vear group meansof the individual mean age scores. The combining of scores Into 3-vear age groups was done to reduce possible errors due to the uncertaintyof the exact age of some individuals. Laboratory Procedures Hematological Examinations. Two 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 ot red cell size distribution) were obtained with the electronic Coulter, which proved verysatisfac- tory and time-saving for this type of field examination. Differential counts were performed in the usual manner after staining with Wright's Auid. Platelet counts were done by phase microscopy, and hemoglobin was determined bythe cvanhemoglobin technique with the Lumitron col6rimeter. Serum proteins were determined with the Hitachi refractometer. Blood and serum samples for the studies described below were collected in the field, kept under refrigeration, 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 hypergiucosuria by reagent paper strips. * In all cases showing positive findings, the urine was centrifuged and the sediment examined mic- roscopically. In the four cases showing positive urine sugar tests, 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 Isiand 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. Complement Fixation Tests. Serum samples obtained from 163 exposed and unexposed Rongelap people were frozen andl sent to the National [nstitutes of Health for various examinations. Com*Clinistix, Ames Company, Inc., Elkhart, Indiana.