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Cosmis rays, which come from outer space, have their
radiation effeet progressively diluted as they pass through the
atmosphere. Thus, a person living at an altitude of about one
.,
“!
mile above sea level receives a dosage of cosmic rays approaching double that of a person who lives at sea level. There are
other variations in the natural "background" dosages.
.
For
example, people living in certain localities of uranium or
thorium mineralization will receive much more radiation than
the average, and their ancestors have received these much
-higher doses.over ¢enturies in many parts of the world.
Living in a brick house, rather than in a wooden house, will,
-with certain kinds of bricks in certain parts of the world,
increase radiation exposure many times over that from test
fallout.
The additional radiation dosageswhich persons
receive from fallout are small compared to these natural
dosages and even the variations in the natural dosages.
To be specific, the dosage to new bone as in children
which results from strontium-90 at present is about the same
as the additional dosage which a resident at sea level would
receive from cosmic rays if he moved from a beach to the top
of a hill a few hundrei feet high.
There is no question that excessive dosages of
radioactive strontium can cause bone cancer and leukemia
in animals, so we should not casually dismiss the possibility of harmful results from test fallout. However,”
keeping in mind that populations are exposed to natural
radiations considerably greater than the fallout dosages,
we can attempt to determine whether these have caused any
detectable effects.
We can examine, for example, whether
there is any obvious increase in the rate of occurrence of
bone cancer and leukemia in populations living at higher
altitudes or in regions of uranium mineralization, etc.
Examination of available records does not disclose
any such effects. However, vital statistics have not always
been carefully kept, and further studies are being carried
on under the aegis of the United Nations Committee to deter-
mine whether any suckeffects can be detected,
One fact is
apparent, however--it certainly is not our normal experience
that people can appreciably increase the occurrence of these
(mor‘e}
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