-~ 6 -
the radiostrontium content of the milk.
So the ques ion resolves
itself largely into "What are the strontiun-90 conte: Ss of whe
foods people in such regions actually consume?" We :’ind on
inspection of the food eating habits and calculation of the
strontium-90 intake relative to calcium, that the increase in
average strontiun-90 concentration of the food due to the low
calcium content of the particular soils can hardly be more
than five-fold for a soil calcium deficiency of 50-fcld. That
is, whereas normal soil carried about 20 grams of available
calcium in the top 2.5 inches, a region with soil of only .4
‘grams per square foot would produce a human body burden
equilibrium of about five times that which the normal soil
“would produce.
.
In order to understand the hazard of radiostrontiun,
which is generally agreed to be the most hazardous of the
long-lived fission products, we try to establish the maximum
permissible concentration both for occupational workers and
‘for the population in general.
These numbers have been set
at 1 microcurie and .1 microcurie for the standard man, rej
spectively.
That is, an occupational worker may carry 1
microcurie of strontium-90 in his body, whereas the eaneral
public should not have over .l of &@ microcurie of strontium90 in the average standard adult. This last figure corresponds to a concentration of 100 micromicrocuries per gram
of body calcium or what we call 100 Sunshine Units, that
is, 1 micromicrocurie of strontiun-90 per gram of body
calcium is defined as 1 Sunshine Unit.
Now, we must try to see in some other way how our
normal experiences can be brought to bear on the question;
"How dangerous is atomic weapons testing from the point of
view of radioactive fallout?"
At the present time we have
in our bodies about .l or .2 of a Sunshine Unit and children
have about one-half of a Sunshine Unit.
In a few minutes
I will speak about the question of the variation from these
average values, but assuming at the moment that these are
the values, what is the threat or the hazard from these
quantities?
Ooviously, they are much smaller than the 100
Sunshine Unit tolerance figure mentioned above.
To cotain
a comparison with normal experience, let us consider the
fact that we know in a general way the magnitude of the
radiation levels to which we are normally subjected by the
cosmic rays, potassium in our own bodies, and the uraniun,
(more)
ER
&
&
B&B
F.
Bm
Hf
&@.
§
a
in
aa
id.
L
iv
r
lat