Toxicity of inhaled 90SrCl2 in beagle dogs. VIII

Studies on the metabolism, dosimetry, and effects of inhaled 90SrCl2 in the Beagle dog are continuing in an effort to provide a basis for assessing the consequences of inhaling 90Sr such as might be released in certain nuclear accidents. Seventy-two dogs have been exposed to aerosols containing 90Sr resulting in initial body burdens ranging from 2.5 to 250 μCi 90Sr/kg. Forty-eight of these dogs are being maintained for lifetime observation. Twenty-five unexposed dogs served as controls. The long-term retained burdens in these dogs range from 1 to 120 μCi 90Sr/kg. Twenty-four dogs with a mean long-term retained burden of 38 μCi 90Sr/kg have been assigned to a sacrifice study. Two of these dogs and 1 control dog were sacrificed at 5 days, 1 month, and 1 year after inhalation of 90Sr. To date, 44 90Sr dogs have died or have been euthanized, 6 during the first 31 days after inhalation of 90Sr with bone marrow aplasia and 38 between 585 and 3473 days after inhalation of 90Sr. The latter group includes 12 dogs with hemangiosarcomas, 15 with osteosarcomas, 3 with fibrosarcomas, 3 with osteochondrosarcomas, 1 with osteochondrofibrosarcoma, 2 with leukemia, 1 with a baso-squamous carcinoma, 1 with a malignant giant cell tumor, 1 with a myxosarcoma, 1 with a transitional cell carcinoma, 1 with an epileptic seizure, 1 with pneumonia, and 1 with cerebellar hemorrhage (5 dogs had both a hemangiosarcoma and an osteosarcoma). The skeletons of the dogs dying with neoplasms received initial radiation dose rates of 4 to 55 rads/day and cumulative doses to death of 3300 to 22,000 rads. Six control dogs have died, 3 during the last year. One had renal amyloidosis, 1 had atheromatosis and arteriosclerosis, and 1 had aspiration pneumonia. Serial observations are continuing on the 22 surviving 90Sr dogs and 16 controls. (U.S.)