ee ee at N a burden range of 0.5 uCi to 50 uCi the observed tumor incidence fluctuated between 0.04 and 0. 371, All of these lung experiments involved intense exposures and a Significant level of carcinogenesis. Severe damage and disruption of tissue were associated with the exposures. The most relevant lung exveriment is Bair's Pu23905 se . . 537- inhalation study with beagles??7°4. Exposure was to particulates of 0.25 u or 0.5 u median diameter; burdens were in the uCi rancse. Twenty of the 21 dogs thar survived more than 1600 davs sost exsosure had lung cancer. cancers were multicentric in origin. Many of these The cancers again acoeared in conjunction with severe lung intury. natural incizenc2 of the disease is smell, Since the it appears that at this level of exvosure the induction of ising cancer is a cerztainty Gurinc the normal beagle life svoan L/ Cember, H., 52° Sair, 52’ Park, J.F., Os. W.J., 3.F. At the same cit. Park, and W.J. Clarke, “Long-term gtude of dinnalec ciutonium in dogs," Battelisa Memorial Institute (Pictnland}), -PwWL-TR-33-214, 1965 (AD-631 637:. w.g. Clarke and W.dJ. Bair, “Thro atfects of intaled 23992535 in beagles," Battelle-Nerinvest Laboratory Annuil Reoort for 13457 to the USAEC Divisisn sf Biology and Mec tsinea, po. Vol. I, Bisalogical Sciences, BNWL-714, 1958, 3.3-3.4. 34, Park, J.F., 22 al, "Proaress in Beacle Sog Studies wi ransuranium Elerentsat Battella-Northwvest,” Health Phvst “ed. 22, No. 6, Jana 1373, OQ. 393-3819. '