«he 36 . hat it would require greater than 32.7 uCi/Kg to cause an acute death. . Indeed, 14 dogs injected with ~ 98 yCi/Ke lived an average of 4.06 years - from time of injection until death. : In these studies referred to above, the animals have been followed until death and the cause(s) of death determined. Six of fourteen beagle dogs | that died after an i. v. injection of 98 uCi/Kg had osteosarcoma, 2 had hemangiosarcoma, 1 had squamous cell carcinoma. In the case of the miniature swine on continuous daily feedings of various levels, there have been a large . number of myelo-lymphoproliferative disorders after cumulative skeletal , Radiation doses of 300 to 19,000 rads. In addition, 5 animals have shown - gient cell tumors or osteogenic sarcomas a bone doses of 8,000 to 14,000 ; rads. On the basis of the data from dog studies, Dougherty and Mays (Ibid, above) predictlifetime doses above which bone cancers may occur in adult humans from irradiation by strontium-90 of 5,000 to 17,000 rads. The results reported for dogs and swine are generally similar and resemble those reported in other species, thus lending a firm basis for extrapolation to man, Studies on radium-226 toxicity have indicated a similar response far dogs and man after equivalent doses, lending further confidence in extrapolation of strontium-90 data to man. The collective dog and swine data indicate. that strontium-90 irradiation does not possess any special feature that’4s not a function of its radiation quality and metabolic characteristics. As sbone-seeking radionuclide, its effects to date appear to be limited solely to bone and hematopoietic tissue. At toxic levels, not only are neoplasms of bone and biood induced, but depression of some of the blood cell concentration suggests a direct dose rate effect on hematopoiesis.