gray somewhat later than men. To study the radiation effect more effectively with these data, measures of radiation dose and hair-graying that can be applied to the individual case were used. Distance from the hypocenter was used as an approximation for radiation exposure. To measure hair-graying, departure from the norm was used; that is, the amount an individual’s score varied from the regression value typical of his age and sex. _The method in this analysis was to use the regression estimate to define an age-specific measure of grayness as : Z = Y’—Y. Y’ is the regression estimate for specified age and sex based on the nonexposed, Y is the numerical value for the individual (0, 1, 2, or 3), and Z is the measure of the individual’s departure from expectation for his age-sex group. Mean values of Z were tested for departure from zero. If, for any sex- exposure group, individuals were more, or less, gray than expected from the re- gression estimates, the mean value of Z for that exposure group would depart from zero and the departure would be tested by Student’st-test. If high exposure (short distance) was accompanied by large negative values of Z, and low exposure (long distance) by values of Z near zero, the relationship would be tested on the correlation coefficients or on the slopes of regression lines fitted to Z and distance. None of these analyses provided evidence that hair-graying is related to distance from the hypocenter. Discussion In this stucly, several simple tests were utilized in an attempt to detect skin changes in irradiated survivors of the Hiroshima bombing; changes that would be indicative of generalized aging acceleration.as a late radiation sequela. The bh 292 -m i GERIATRICS, JANUARY 1961 Cc J most direct test was guessing the age of clinic subjects without knowledge of their irradiation status. This very simple observation may have been the most important, since it established the fact that irradiated individuals do not appear older than their nonirradiated cohorts. The pathologic components of skin ageing are mostly related to degeneration of skin elastic fibers and to loss of subcutaneous fat. Skin retractility was measured as a direct reflection of elastic tissue in the skin. A skin fold measurement (essentially wrinkling) was more directly related to loss of subcutaneousfat, although loss of elasticity did play a role. The methods of skin measurement employed were not as elaborate and were perhaps less sensitive than those employed by other investigators.!1 However, the methods used lent themselves better to large population surveys. In spite of the moderately large samples used in this study, no relationship to radiation exposure and skin aging was noted. Hair graying is of particular interest, not only as a manifestation of aging, but also as it relates to the epilation experienced by heavily irradiated subjects in 1945. Data on the age incidence of gray hair, as well as the semiquantitative grading of degree of graying, failed to show differences between the exposed and nonexposed. This was true even though epilation subsequent to the bombing was a common symptom of the most closely exposed group in the sample. The concept of nonspecific shortening of the life span after irradiation has been based primarily on experiments in rodents. This concept is that decreased longevity results from irradiation, and that this decrease is not related to lifeshortening diseases specifically induced by irradiation. In these experiments on rodents, specific metabolic or endocrine 35