- 24 equilibrium cencentration of human bones if testing continued
indefinitely at the average rate of the past five yea 3.
This level wou_d be approached only after a few decacd 3,
After 25 years the level would be half of this equilii cium
value, and after another 28 years, 56 years total, frun an
arbitrary beginning which we have set as 1952, we would ex
pect’ in the year 2008 three-fourths of the equilibrium
figures.
So somewhere between 4 and 15 Sunshine Units of
strontiun-90 in human bones in the United States might ree
sult from the present type of testing being continued for
the next 50 years.
In those certain areas in the world where the soil
is low in calcium, this level might go five-fold nigher. At
the present rate of testing we might indeed approach the
figure of 100 Sunshine Units, the tolerance limit for large
populations, at the beginning of the 2lst century for these
certain limited regions in the world.
The observed conditions in these regions could be relieved, however, by
fertilization of the soil with calcium, either calcium
nitrate or lime being used, as appropriate from other conSiderations.
The Sunshine Project continues to study the problems of world-wide falloute-the stratospheric inventory of
radiostrontium and radiocesium, the occurrence of these
isotopes in the soils and water and the biosphere all over
the earth, the diological effects at certain levels of
contamination with strontium-90, and to a lesser degree with
cesiun-137, ana the possible genetic effects of the icw gamma
ray dosages associated with world-wide fallout from atomic
tests.
All of these are studied not only with the point in
mind of devising methods of protection against atomic warfare,
but also with the thought of possible application in the re~
mote event of industrial accidents which may happen in connection with certain of the peaceful uses of atomic energy,
particulariy atomic power.
Certainly an understanding of
the basic principles of world-wide fallout is applicable to
the control and safe-handling of isotopes.
All of this is
done in colliabcration with the United Nations Scientific
Committee on the Effects of Atomic Radiation, and it is to
be hoped that as the data appear all of the countries in
the world will join together in this international effort
to understand ctetter the effects of the great new fact in
life, the nuclear atom.
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