MILLIRADS
741
Fig. 2—Bone dose received by New
York City residents by the end of
1963,
0
5
10
15
20
25
30
AGE IN 1963
residents if there is no further testing probably will not be too different
from the average value of 174 mrad estimated by the United Nations
Scientific Committee on the Effects of Atomic Radiation (UNSCEAR)
for the worldwide average per capita dose commitment.’
Much more data will have to be obtained before the problem of
relating diet and bone Sr levels is completely solved. Efforts are
being made to obtain measurements of stable strontium levels in bone
and diet as well as *°Sr so that comparisons of changes in true specific
activity in bone can be related to changes in the diet. Such data will
lead to estimates of the turnover rate which are independent of the
strontium/calcium discrimination considerations.
A more precise knowledge of strontium metabolism in man will be
necessary before the risks incurred as a result of exposure to *’Sr in
the diet can be quantitatively evaluated. Such an evaluation must be
made, for example, when a decision has to be reached as to whether
or not remedial action to reduce risk under given circumStances is
warranted. It is also necessary if more precise estimates of dose
commitments as defined by UNSCEARare to be made.
REFERENCES
1. H. H. Mitchell, F. R. Steggerda, and H. W. Bean, J. Biol. Chem., 158: 625
(1945).
,