28 those >35, exposed and unexposed, were free of clinically detectable peridontal disease. In the aged, manyof the remaining (ceth were simply sheld in position by the gingival attachment. Almost all the Rongelapese exhibited marked xerostomia. The oral mucosa felt damp but not wet. During the dental examination, manipulation of the tissues by mouth mirror and explorer failed to stimulate the flow ofsaliva. For pH readings, the paper strip had to remain in contact with the floor of the mouth for 25 to 30 sec in order to absorb sufficient saliva. In most instances it was difficult for the subject to produce the 5 ml of saliva necessary for pH determination in a period <10 to 15 min. The fH values ranged from 6.0 to 7.5, with an averageof 6.3 Utirik Population The Utirik population exhibited oral findings similar to those of the Rongelapese. Their standards of oral hygiene were somewhatsuperior, but the incidence of peridontal disease and caries in adults was practically identical. In the Utink children less evidence was seen of bunching ofthe lower anterior teeth, and jaw development was in harmonywith general body growth. Conclusions These examinations led to the following con- clusions. 1. There was no significant difference in either caries rate or incidence of peridontal disease between the exposed and the unexposed people of Rongelap. The level of oral hygiene appeared to be somewhat better in the children examined at Majuro and at Utirik, but the incidence ofcaries was about the same in the two groups, and higher than in the Rongelapese children. 2. The poor ora] hygiene generally observed in the Marshallese people had its usual results: a high caries rate in teen-age children; severe peridontallesions in adults (heavycalculus, loss ofalveolar bone); and edentulous mouthsin the aged. 3. No difference was perceptible in the clinical appearance of developing dentition amongthe ex- (open circles, exposed people; closed circles, unex- posed people) to showthe spread of the data, and the mean values are also plotted (squares) for cach 5-year age group with exposed and uncxposed people combined. Thetrend of each criterion with increasing age is represented bya line of approximate best fit by eye. The values of the criteria generally either increase or decrease with increasing age. Many changes, such as greying ofthe hair, balding, arteriosclerosis (peripheral and retinal}, and skin looseness and retraction, are not appeciably manifest in the Marshallese until after age 35 to 40. There is a tendency for values of criteria such as blood pressures, greying of the hair, loss of visual] acuity, and accommodation to level off, or even to showslightly reduced values in the oldest groups. The numberof people in these groupsis too small to make this observation certain. However, American statistics on blood pressure(systolic and diastolic) also show a plateau effect beyond about 60 years of age and evena slight tendency to lowering of blood pressures beyond this age.”* By the age of 65 to 70, arcus senilis in all Marshallese showed a 4 + change and, therefore, the plateau was at a maximum. Some curves showed lower maxima. For example, baldness in women showed only a 35% maximum, and arteriosclerosis of the retina only 45%. The differences in maxima probablywere due largely to differences in the degree of change associated with the various criteria but also partly to the arbitrary nature of the scoring. The sexual differences in hand strength and baldness were expected. In the neuromuscular functiontest, slight muscle fatigue mayhave been a factor in the lower female scores, necessitating separate evaluation. DOE ARCHIVES TTT TT 7 vt cr EXPOSED eeUNEXPOSED ®«VIAN BOTH GROUPS 100 c— se oo posed children, the nonexposed, and those born to irradiated parents. STUDIES OF AGING CRITERIA The results of aging criteria studies are plotted in Figures 13 to 31. Individual readings are plotted Figure 13. Skin retraction time, 1958-1959. 390