Merril Eisenbud - -26 1 Jamary 27, 195k Dr. Bowers presented some retention data for radium in dogs. He noted that 60% was retained in 2; hours in adults and 386% in a Semonths old animal. ‘Twanty per cent of the dose was in the skull and vertebrae. Dr. Morgan reported lower values for inert strontium in bone than have been previously reported, i.e. 7 ppm in vertebrae instead of 60. These analyses were made with a neutron activation technique whereas the old ones were based on spectrographic analyses. Comparisons of the two techniques have not yet been done adequately. Comar noted that strontium excretion in milk is about 0.1 of calciun, The strontium calcium deposition ratio in the fetus ia 0.2 and in the adult 0.3. Strontius excretion in cows is about 0.1% per day after it becomes constant. ‘The problem of madifiRising toxic materials from the bone is complicated by the fact that recrystallisation is so rapid that the anterial tends to be fixed py within the bone in a short tine. After sectioning bone in which Ca“? was fixed in-vivo, only 50% of the calS could be likerated by in-vitro exchange, ‘The excretion of strontiun in sheep and cattle is quite similar to the few excretion data available on humans but the comparison is inadequate becanse of the paucity of human experiences, Dr. MecDonald suggested that stable strontium may be present in an irregular distribution as indicated by the radioautographs of animal bones pretreated with radioactive strontiun. Dr. Comar thought that the presence of stable strontium in the body was not an important consideration since strontium probably exchanges with calcium. The spottiness of strontium deposition may be a function of the irregular ingestion, The “hot spots" obtained after injection of radioactive calcium are 6 to 15 Sines average level of radioactivity in the bons. This is also true for .« This consideration may be important from the point of view of tumor production although Dr. Brues recalled the experiments indicating that diffuse radiation is more efficient in tumor production than equivalent amounts of radiation delivered in pinpoint fashion, at leasté on skin, Dy. Hoecker reported some of his experiments which indicated that the removal of calcius from an imoobilized limb was accompanied by a reduction in the radium content suggesting that the radium is deposited in association with calcium. He also noted that “hot spots® occurred in human cases of sarcoma fron radiun. In a discussion of the pathological changes produced by strontius, Dr. Comar reported that hematopoietic changes were observed at 10 tims tolerance and bone trabecular "severance" was seen at 100 times MAC. There was no evidence of permanent damgse. Dr. iten mentioned That Dr. Friedell administered 10 millicuries of to a patient which was about a lethal dose. ‘This svwoked a searching of minds for cases of accidental exposure in humans and a number of such instances were recalled. Dr. Hamilton also mentioned a monograph on strontium pO’ ARCHIVES