274 R. A. Conard human beings. From experiences with the Japanese exposed at Hiroshima and Nagasaki and from animal studies, certain late effects of radiation may possibly develop in the Marshallese. Results of observations for such effects will be presented accompanied by appropriate discussion related to findings of others. 2.2.1. Shortening of life-span Thus far the three deaths in the exposed group represent about the same death rate as has been observed in the Marshall Islands as a whole over the same period of time (about seven deaths per 1000 per year). Numerous investigators have reported shortening of life-span of animals exposed to acute and chronic radiation (Blair 1956, Bennett, Chastain, Flint, Hansen and Lewis 1953, Brues and Sacher 1952, and others). Chronic exposure of radiologists in the United States was reported to result in life-shortening compared with other physicians (Dublin and Spiegelman 1948, Warren 1956). In view of the above findings, some life-shortening may be expected in the Marshallese, though in view of the small size of the population a number of years will no doubt be required before such an effect of radiation can be evaluated. 2.2.2. Premature ageing and degenerative diseases From observations over the past five years the impression is that the exposed Marshallese dé not appear to have aged faster or appear older than unexposed Marshallese of the same age. No doubt the subtle changes which occur with ageing would be difficult to detect over this period of time. The incidence of degenerative disease has been about the samein the exposed as in the unexposed group. An attempt is also being made to study ageing from a more quantitative clinical approach. Certain criteria usually associated with ageing that can be easily obtained on physical examination are recorded as nearly quantitatively as possible, either by direct measurement or estimation of degree of severity of criteria in a scale from 0 through 4+. Though the workis in the early stages and only preliminary analyses have been carried out, it might be of interest to outline some of the criteria which are being investigated. Skin: Special calipers with spring tension have been designed for measurement of (a) looseness and (5) elasticity. Looseness is measured in millimetres height of the fold of skin anteriorly at the junction of the neck and chin. Elasticity or resilience of the skin is determined by clamping a fold of skin on the back of the hand for one minute, releasing the calipers and measuring the time in secondsfor retraction of the fold to the normal skin level. (c) Senile changes in the skin, such as keratosis, pigment changes, and warts (0-4+). Eyes: (a) Visual accommodation measured in dioptres, (6) arcus senilis (0-4 +). Hearing: Loss of hearing at 4000 frequency. Cardiovascular: (a) Peripheral and retinalarteriosclerosis (0~4 + ), (5) systolic and diastolic blood-pressure readings. Vigour: (a) Vital capacity of lungsheight, (6) hand-grip strength, as measured with a hand dynameter in kilograms. Neuromuscular function: Number of depressions of the key of a hand tally (blood counter) in one minute.