and carcinoma as you go to higher doses. For instate, at the higher doses you will find much more leukemia than carcinoma, because cdthe time of onset, and the animals die before they are old enough to get carcinoma. At the lower doses I would guess -- this may not be the right number -- I would find there is a positive index for leukemia production in doses above 100 roentgens or so many. I am not sure that this will be forthcoming when this is written up. CDR. CONARD: Alderson Reporting Company Washington, D. C 10 11 What was the threshold dose for opacities? 12 MR. HARRIS: At half the year -- these are not non- 13 vision disturbing capacities -- is in the neighbpjrhood of 14 50 r for x-ray. 15 16 CDR. ETTER: beforehand for any lens aberrations? 17 18 MR. HARRIS: run, 21 22 23 ARC 24 Yes, they were. this was an experiment 19 ' @liminate all bias. 20 Were those mice carefully screened The way they were in which we attempted to All items were coded singly. The observers over the period of two years never knew what animal they had hold of. ally on that basis. We think it is pretty good statisti e- There is a fair percentage d@ visible aberrations in control animals as you put the data back together again off the card files. The threshold, if you wish to call it that , or the ¥ 77