88
RADIATION STANDARDS, INCLUDING FALLOUT
Representative Hosmer. I have one question, Mr. Chairman. Do
I understand, Dr. Comar,that the ratio of stable strontium to calcium
is a little lower than the ratio of strontium 90 to calcium in your
charts?
Dr. Comar. Yes. As time goes on and we approach steady state
these ratios should become identical.
But that would take many,
many years. So at the present time one of the earlier charts indicated the actual ratio as compared to the theoretical.
In other words, with the value of total diet equal to 1, milk now
is running 0.6 to 0.9, whereas theoretically it would run 0.22. As time
goes on it would approachthis value.
Representative Beren, Will you proceed, Dr. Comar?
Dr. Comar. I would like to have in the record the next paragraph
but it has been discussed among us and I think the point has been
well made.
Representative Price. The complete statement will go into the
record.
(Complete statement of Dr. Comar will be found at the end of his
testimony,p. 95.)
Dr. Comar. This concept is of such importance that I should like to
restate it in terms of practical application. Human beings and animals of all ages must have a certain amount of calcium in the diet
to build new bones andteeth or to remodel and rebuild bones already
formed. Calcium in the diet comes primarily from dairy products
and plant foods, both of which contain Sr®. The calcium from dairy
pro ucts will most always have less Sr” than the calcium from plant.
‘oods because of discrimination by the cow.
If the consumption of dairy products is reduced without compensating addition of minerals, the body has to use plant sources of
calcium for building and replacementof bone.
In effect, this means that reduction of the intake of dairy products
will raise the Sr®°°-Ca intake and therefore the body burden of Sr*°.
At present and foreseeable levels of Sr® it appears best to follow
accepted nutritional practice.
The question is often raised as to the advisability of supplementation of diets with stable calcium or stable strontium, for purposes of
reducing the body burden of Sr®.
This matter is now considered, leaving aside the question as to
whether reduction of present and foreseeable body levels of Sr°? would
in fact improvehealth.
The Sr*°Ca ratio of the diet can be decreased by supplementation
with uncontaminated stable calcium and this in principle should
decrease the Sr®° levels produced in the body or milk. Although such
reductions have been demonstrated in experiments with laboratory
and domestic animals, there are many considerations and unknown
variables that restrict. practical application.
Experiments with dairy cows have shown that long-term supplementation of rations with stable calcium can reduce the Sr®? levels in
milk, but probably not greater than a factor of + even under the
best conditions, because of abnormality of diets.
There are uncertainties in regard to the effects on animal nutrition
und health from high calcium intakes over long periods of time, and
in regard to the length of time it requires for calcium supplementation to becomeeffective.
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