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C-O-N-F-I-D-E-N-T-I-A-L- 3 -00-3-3,283,411This is apparently due to the high acceptance of data pub-lished by the University of Rochester. It was pointed out that the possible contribution of radioactive dust composed of other than radon daughters was not actually evaluated in the case of the Schneeburg lung cancers because dust samples were not collected. Although radon is released by crushing of ores, radon and radon daughters were not con-sidered to be a problem in uranium mills of France because of large work areas and high ventilation rates.e. Four papers from the USSR dealt with laboratory studies on the toxicology of internal emitters in general, particu-larly Cs137, Sr89, Sr90, Y91, Ce144, Zr95, Ni95, Ru106, and uranium and radon. Most studies involved intratracheal ad-ministration of the isotopes, although a few inhalation studies were described. These papers were all given by Dr L N Burykina in the absence of Drs Moskalev, Sanotsky, Novikova and kushneva. They report that 10 to 18 per cent of the inhaled radioactivity was found in the lungs of rats and dogs after exposure, and that five per cent was cleared by ciliary activity. These data are difficult to evaluate since the particle sizes of the aerosols were broadly des-cribed as being between 1 and 4 μ. Translocation of the inhaled radioisotopes was similar to that reported by others.f. Biological effects were reported only for intratracheal ad-ministration of Ce144 and Ru106. They report degenerative inflammation of the lung and aplastic changes in the bone marrow accompanied by leukopenia in acute stages. In longer term studies they find chronic pneumonia and degenerative and proliferative changes of the bronchial epithelium and connective tissue. They also reported reduction of bone marrow hematopoiesis and degenerative changes in the liver, kidney, etc. These occurred after deposition of 1 to 19 με Ce144 in rats, 0.6 to 2.6µc Ce144/gram of dog, and 0.4 c Rul06/gram of rat. No cardiovascular changes were noted, but were not specifically studied. The results of studies with uranium were similar to those reported many times, with the exception of central nervous system injury which consisted of changes in conditioned reflexes and in hibitory and ex-citatory processes, Due to this and relatively high burdens found in skeletou (3 to 4 per cent) they conclude that uranium toxicity is not necessarily confined to kidney damage. Kush-neva's paper on synergistic effects of silica and radon re-ported previously published data. Silicotic rats were exposed to 8 μc radon. The radon treated silicotic rats showed more serious clinical symptoms, drop in circulating blood cells, and more extensive lung pathology than rats treated with radon or cilica alone.g. An excellent paper describing experimental work on the in-halation of Rn222 and its decay products was presented by Dr E Pohl from the University of Innsbruck, Austria. When Rn was inhaled in equilibrium with RaA, RaB, and RaC the concentration of daughters in lungs and other tissues were higher than when the concentrations of RaA, RaB, and RaC in the inhaled air were less than the equilibrium values. However, in the latter case the concentrations of daughter products in the lungs and other tissues were higher than would be predicted from the concentrations in the inhaled air. Further experiments are in progress to confirm and explain these results. Similar, but less extensive, studies were reported in a paper co-authored by Dr Lafuma of France and Medjidovic of Yugoslavia.C-O-N-F-I-D-E-N-T-I-A-LCONTROLLED DISSEMNO DISSEM ABROAD