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SESSION IV DISCUSSION
RIVERA: In regard to cesium coming up from thesoil, I think
Wright Langham pointed out that it very critically depends on the soil.
We know, for example, that in Rongelap a lot of foods are highly con-
taminated -with cesium. It is not due to current fallout; thereforeit
must be getting into the food from the soil.
WARD: It should be pointed out that the soil is also quite different
from the agricultural soils in this country as I understand it.
RIVERA: One of the earlier speakers showed a soil depth of pene-
tration profile, and there was a little bump for cesium at 18 in., I think.
I wonder what the explanation for thisis.
HAWTHORNE: I think you will have to treat that as an experimental
fact. I don’t really have an explanation for it. I will speculate here and
say that it may be concerned with the previous cultivation regime and
represent where the top layer of soil was turned upside down and then
sampled before it was returned.
FROM THE FLOOR: Is it difficult to control the influence on the
assimilation of these various nuclides in the dietby the vitamin balance
in the feed, e.g., tying vitamin D and calcium together? Is this difficult
to do or is it, in fact, considered ?
BENINSON: I don’t know. My data were juston people under normal
conditions. I don’t know of any experimental work. Dr. Comar may
wish to commentonthis.
COMAR: One can produce small changes in the absorption and re-
tention of various radionuclides by dietary changes. For example,
vitamin D or lactose will increase absorption ofalkaline earths, but not
much can be done and a normal diet still be maintained. By use of an
abnormal diet, it may be possible to change absorption by a factor of
aS much as 2, 3, or even 4, but with normal diets it is very difficult to
do so.
RIVERA:
I wonder if Dr. Thompson considers any of the diets,
any of the variances he calculated, abnormal?
THOMPSON: No, I would not say that any of the diets used in the
calculations were abnormal.
LENGEMANN: Several times during the presentations, we were
given residence times of nuclides on plant foliage. We have had values,
depending upon half-life, or 3 to 18 days and so on, but the statement
has been made that when only the residence time is considered, i.e.,
when the radioactive half-life of the nuclide considered is eliminated,
that there is relatively little difference between the isotopes of strontium, cesium, and iodine. I wonder whether we should observe differ-
ences between these materials as far as residence time on pasture