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84
RADIATION STANDARDS, INCLUDING FALLOUT
category would contain about 250 milligrams less and the milk about
250 milligrams more calcium; the relative strontium-to-calcium rela-
tionship in milk would be about the same as indicated.
This difference comes about because the British enrich their bread
with mineral calcium, whereas in the United States milk solids are
used for this purpose.
The meaning and implications can better be grasped from chart 3,
which presents the same information-normalized to a Sr-Ca ratio in
the diet of 1.
It is first noted that the Sr-Ca ratio of milk is one-tenth that of the
plant foods. The milk value is 0.22 as compared to the plant value
of 2.2. This is because the cow preferentially utilizes calcium over
strontium by a factor of 10 for milk secretion. It is obvious from
this diagram that if an individual reduced milk consumption to zero
and derived all of his calcium from plant sources, the Sr-Ca ratio of
his diet would be doubled.
In other words, if an individual reduced his milk consumption to
zero and all of his strontium and calcium came from plant sources,
the value would be 2.2 instead of what wesee as 1 in the total diet.
Chairman Ho.irtevp. This is a very important comparison you are
making there, Doctor. Those who advocate to stop drinking milk
because of the content of it would be in the position of advocating the
element in food which is only one-tenth of that which would be deposited on vegetable plants, if I understand your comparison.
Dr. Comar. This is correct. This is a major point that I did want
to bring home.
Chairman Ho.irtetp. Of course, the other side of the picture would
be that because of the fact that milk is consumed more by infants
and children rather than plants, that milk, still from the standpoint
of children and infants, would be the greatest contributor to their
absorption; is that not right?
Dr. Comar. That is correct.
Chairman Hotirtetp. Particularly young children that have not
yet gone on solid diets?
Dr. Comar. Yes. But if plant sources were substituted for milk,
even for young children, this would then tend to raise the strontiumto-calcium intake.
Chairman Ho.irretp. Would you state specifically the major point
that you said you wanted to bring home here?
Dr. Comar. I have repeated this several times, and it will come up
again. It is this: That if an individual reduced milk consumption to
zero and derived all of his calcium from plant sources, the strontiumto-calcium ratio of his diet would be doubled.
To carry on, conversely, if an individual derived all of his calcium
from milk, his diet would have about one-fifth the typical strontiumto-calcium ratio.
In a minute we will talk about the actual situation in regard to
strontium 90 which does not come up to this particular chart as yet,
but will approach it with time.
Chairman Houtrretp. Will you give us the significance of the balance of that chart, Doctor, where you show mother’s milk as one-tenth ?
Dr. Comar. I will come to that in a momentJater in the statement.
Thesignificance of this pointis emphasized by recognition of the fact
that the amounts of strontium 90 and calcium in the total diet determine the body burden of strontium 90.
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