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INTRODUCTION AND CONCLUSIONS
WORLDWIDE EFFECTS OF ATOMIC WEAPONS
We assumehere high-altitude bursts, with the immediate area of ground
zero receiving no more than its proportional share of the fallout debris.
Exchange of debris between the earth's hemispheresis also neglected. The
over-all assumption is pessimistic.
2. Atmospheric or other natural storage mechanisms that might
allow appreciable Sr°° decay before it becomes available to
humans.
Whether Sr®® is stored in the atmosphere or in the biosphere, this con-
sideration is not likely to increase’ our estimate by more than a factor of
two.
3. Availability of Sr°° in debris for transfer to the biosphere.
We believe that the bulk of the Sr°° is plated out on the surface of the
debris particles and that it is also scavenged out in solution by rainfall.
Thus it should be readily available for take-up by the biosphere. If our
reasoning is incorrect and the Sr°° ts contained inside insoluble particles,
the calculation given below should then be regarded as highly pessimistic.
4. Availability of natural strontium in soils.
The parameter used here is 60 lb of agriculturally available strontium
per acre. We feel that over a period of time such as we are considering,
more fixed strontium in the soil will become available. The better value
lies somewhere between one and twenty times this amount. Having used
the lower limit, our estimate in this respect is also pessimistic.
5. Redistribution of Sr°° by plowing, fertilizer, etc.
Fallout debris deposited on untilled soil is not leached down very effectively by rainfall. In agricultural areas (the areas of interest), however,
the soil is constantly well mixed to an effective depth by the efforts of
man. We also assume wash-off as relatively low. These considerations, in
themselves, make our calculation pessimistic.
6. Content of natural strontium in bone.
The average U.S. adult, normalized to the “Standard Man,” contains
0.7 gm total strontium in his bones. This figure is probably rather accurate.
On the basis of the above assumptions and other phystcal parameters,
7
the preliminary SUNSHINEestimate of the nuclear bomb yield required to
bring the population of the world up to Maximum Permissible Concen-
tration 15
larger than 2.5 X 10‘ megatons (MT).
We have taken the liberty of normalizing the GABRIEL models to an
MPCof1 pc and have corrected the Sryield factor. For comparison with
the preliminary SUNSHINE estimate, the GABRIEL gauge lies between
20 MT and 9 X 10* MT.
An estimate developed on a calcium-strontium modelhas indicated an
800 MTlimit; the uncertainty of this limit is unknown, butit is probably
pessimistic, since parameters similar to the strontium-ratio type ofcalculation are involved.
Thus, the SUNSHINE methodology achieves minima that lie close to the
maxima of all previous models.
RECOMMENDATIONS
It is seen that a number of physical and biological parameters remain
to be determined to greater exactitude; many are unknown to several
magnitudes. Until comparatively recently it would have been extremely
difficult, if not impossible, to obtain a measure of a numberof the param-
eters. Today we are afforded the opportunity of doing a radioactive-tracer
chemistry experiment on a worldwidescale.
The release in the world of several kilograms (kg) of Sr°° within less
than a decade has probably disseminated enough of the contaminantto
provide amounts that are probably now detectable in samples of inert and
biological materials throughout the world. An analysis of these materials
for St? will provide us with much of the information that is now
lacking.
For our model we will also require an analysis of the ordinary strontium
content of soils, waters, and biological materials. Other requirements may
appeay_as the program develops.
It is rather striking that the last comprehensive measurements of souls
for natural strontium were made in 1914-1917.The strontium cycle in
the biosphere is almost completely unknown, and unknown meteorological
factors abound. We submit, therefore, that the adoption of a sampling