Untied States of America (Continued) 5. Similar operations would be valuable in assessing the activity from future tests and in gathering valuable data for oceanographic studies. G/R.57 GONADAL DOSE IN ROENTGEN EXAMINATIONS —A LITERATURE SEARCH Contains results of literature research which show the estimated contribution of gonadal dose by standard medical roentgenographic procedures. Contribution to the gonadal dose of certain examinations, such as examinations of teeth, skull, chest, and extremities, is relatively insignificant, when compared to the case of pelvic and abdominal examinations. It should be noticed that the dose to the foetal gonad is important genetically. G/R.64 SHORTENING OF LIFE IN THE OFFSPRING OF MALE MICE EXPOSED TO NEUTRON RADIATION FROM AN ATOMIC BOMB Length of life in the offspring of male mice exposed to moderate doses of acute neutron radiation from a nuclear detonation is shortened by 0.61 days for each rep received by the father over the dose range tested. This figure excludes death before weaning age. The 95% confidence limits are 0.14 and 1.07 days per rep. Extrapolating to a proportional shortening of life in man gives 20 days per rep received by the father as the point estimate and 5 and 35 days as the 95% confidence limits. The offspring were obtained from matings made from 19 to 23 days after irradiation and, therefore, represent the effect of irradiation on germ cells in post-spermatogonial and sensitive stage of gametogenesis. It is probable that irradiation of spermatogonia (the stage that is important from the point of view of human hazards) would give a somewhat smaller effect. However, since the present data show an effect on the offspring which is as large as the shortening of life in the exposed individuals themselves, it seems likely that, even when allowance is made for the conditions of human radiation exposure, shortening of life in the immediate descendents will turn out to be of a magnitude that will warrant serious consideration as a genetic hazard in man. G/R.65 GAMMA-RAY SENSITIVITY OF SPERMATOGONIA OF THE MOUSE Relates the depletion of spermatogenic cells to killing of spermatogonia, the repopulation being related to the maturation of surviving celis. G/R.66 SOME DELAYED EFFECTS OF LOW DOSES OF IONIZING RADIATIONSIN SMALL LABORATORY ANIMALS A quantitative study of the life span, the incidence of leukemia, tumors (lung, liver, ovary), and lens opacities as a response to low dosages (less than 100 rads). G/R.67 EFFECTS OF LOW-LEVEL RADIATION(1 TO 3 r) MITOTIC RATE OF GRASSHOPPER NEUROBLASTS A study of the inhibitions of mitotic rate and of its possible relationship with the alteration of chromosome structure. G/R.68 EFFECTS OF LOW DOSES OF X-RAYS ON EMBRYONIC DEVELOPMENTIN THE MOUSE Effects of 25 r applied during different stages of embryonic development on skeletal malformations appearing in the young. G/R.71 OCCUPATIONAL RADIATION EXPOSURES IN U. 8S. ATOMIC ENERGY PROJECTS G/R.72 WORLDWIDE EFFECTS OF ATOMIC WEAPONS (A comprehensive preliminary report on the Sr®* problem up to 1953) A preliminary report discussing the various aspects of long-range contamination due to the detonation of large numbers of nuclear devices. An improved methodology for assessing the human hazard is developed, and an extensive experimental program is proposed. 199 melon