GENERAL DISCUSSION 



T. C. RucH (University of Washington, Seattle, Washington): I want to ask 

 Dr. Brown what he means by "high, medium, and low" doses in terms of lethality? 

 As you know we have no reliable published data on the lethality of radiation in 

 monkeys and this might give us objective definitions. The other thing I would 

 like to know is whether members representative of the high, medium, and low 

 groups are trained simultaneously by the same personnel, the same time of year, 

 on the same apparatus, and so on? 



W, Lynn Brown (University of Texas, Austin, Texas): First of all, the groups 

 were divided before the act so that we could reach certain statistical requirements 

 in the handling of the data. As to high, medium, and low, we are using descriptive 

 terms. Group C was the highest group. All the animals in Group A were lost. 

 Of 8 animals in Group B, 7 were lost. Consequently, that group or the single 

 animal was not included. In the high dose group, we lost 5 of 24 animals. In the 

 other groups, we have few deaths. We had two deaths in the medium group and 

 one in the low dose group. So, we were using these terms rather than stating each 

 time what the dosage was, and we are dealing with a variable dose of radiations 

 — mixed gamma-neutron radiation. The problem is an Air Force design problem 

 in radiation. We psychologists did not design this problem, but the Air Force has 

 certain problems with reference to radiations that they wanted solved, and these 

 animals were assigned to these dose levels. Psychology had a somewhat minor 

 role, compared to hematology and bone marrow. Despite the designs, we have been 

 able to test out a number of relations which are consistent between the laboratory 

 exposed animals to gamma-neutrons and the Nevada field tests. 



T. C. Ruch: Have you an LD/50 for 30 days? 



George M. Krise (Texas A & M College, College Station, Texas): Mackey has 

 reported it in the same report, 555 plus or minus 25. 



Harry R. Harlow (University of Wisconsin, Madison, Wisconsin): I am sure 

 we are gradually accumulating data on the LD/50/30. We have had no animals 

 go out on 500 r. We have had better than 50% survival after a single dose of 

 600 r. We are accumulating a large amount of data on fractionated doses, and 

 when these are extrapolated, these factors on the LD/50/30 for monkeys will be 

 somewhere between 600 and 650 units. 



W. Lynn Brown: In the range of 650 units would be a guess, for a while 

 then, for a healthy animal. 



C. D. Clemente (University of California, Los Angeles, California): I would 

 like to ask a question about the onset of generalized radiation sickness in animals 

 that have sustained head radiation alone. Dr. Arnold made the statement that head 

 radiation in rats was able to produce a generalized radiation sickness. In our 



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