PRETREATMENT OF ANIMAL WASTES CONTAINING RADIOISOTOPES WITH DRY-DISTILLATION

Mice that had been radiolabeled with one of seven isotopes by intraper itoneal or subcutaneous administration were dry-distilled at 800 degre es C for 10 min, and the fate of the radionuclide was examined. The ra dionuclides administered were H-3, C-14, P-32, S-35, Ca-45, Cr-51, and I-125, all of which are commonly used in animal experiments. After dr y-distillation, 95% of H-3 was found in the distillate (condensate), a nd 80% and 16% of C-14 were recovered from exhaust gas and residual so lids, respectively. Only between 10 and 20% of S-35 was found in disti llate. The remainder of the residual S-35 was recovered from the inner wall of the exhaust vent of the dry-distillation equipment. About 24% of I-125 was also recovered from the inner wall of this same exhaust vent, and the residual radioactive materials were recovered from the r esidual solids. On the other hand, P-32, Ca-45, and Cr-51 were recover ed entirely from the residual solids. The weight of the animals decrea sed to about 10%, and the volume to about 20% (mice and rats) to 40% ( rabbits) after dry-distillation. The residual solids of animal wastes generated by dry-distillation were odorless and chemically and biologi cally stable. Dry-distillation has many merits as a pretreatment for t he disposal of animal wastes containing radioactive material because o f the easy handling, storage, and transportation of the residual solid s.