70 DR. BUGHER: Are most of those excreted rather rapidly? MR. COHN: Zirconium, cerium, praseodymium are concentrated in the bone to some extent. I think in this case their half life is probably much shorter than their excretion rates. That would be the determining factor. DR. BUGHER: It is obviously unlikely that we will ever know more quantitatively what Alderson Reporting Company Washington, D. C. we know now ; in other words, is in these people than we cannot really. acquire any 10 more knowledge by deferring consideration of anything 11 because we really have in our hands now all the evidence 12 that there is. 13 CDR. | - CRONKITE: Does the exposure to 150 to 200 r 14 in relativdy a short time change tolerance concepts? 15 this influence the tolerance concept? 16 animal experimentation where you crack them with a couple 17 of hundred r and see if your same tolerance levels will hold 18 up? 19 2 21 Has anybody done any | DR. BUGHER: The main point there, I think, 23 24 25 is that our tolerance levels are below that for which experimental results can be demonstrated. In other words, one has to go much higher levels of the material. ARC Does have been experiments on such things. There At the moment I can't recall the results except that they tend to be additive, rather than otherwise. )¢