y “4 y ty w ah ti h SC4E FURTHER CONSIDERATIONS ON RADIATION DOSAGE TO SHEEP FROM FALL-OUT DURING THE SPRING 1953 NUCLSAR WEAPONS TESTS A. BEST COPY AVAILABLE Intreductim Caleulatics of radiatio dosage tothe thyroids of sheep ingest- ing falleout have been made alsewhere (1). It was thera concluded that these doses were not Llarrs enon to account for deaths amonz the animals. It is centended here that althouth the activity found in the thyroid serves as an index of total radiation exposure, tha thyroid dose is but mea of several possible types of internal irradiation which will occur when inzestim of mixed fission products has taken clace. Ths most important of thes3 appears to te the dose to the bone marrow fren long lived isctopes with 3low biological turnover. This effsct has zensrally bien ocmsidersd to be chronic in character, but it appears possible that "short term" effects may also occur if th3 concentrations are gu:ficiently high and tho emitters are of moderat ly Long half life. Stronz evidences of bens mavrow damage hs been fomd in sgauples taken froam the skeletcns of several of these animals and subjected to histopatholotical examination (2). This accenpanies the avidence of thyroid and other damage also observed, and is undcubtedly of sreat:r importance than the latter tothe survival and wall veing of tha animal. These observations and the calculatims presented here constitute rather stron arguments Tor the conclusion that radiation 2ffects played an important [role inyehp,decnesesdvs mortality cbserved amonr the aninals. CLASSFATGece 326 U...oRIss) ENERGY nlRG PROPrer Or " ty.wo.Caecek~ahste7 Dee9 MISSIO - Collection Box Folder 2A “4365 F