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(fission) bomb yield required to bring the population of the world up to
the maximum tolerable amount of contained Sr-90 is 25,000 megatons.
This
is believed to be a firm lower limit, on the ground tnat the quantitative
assumptions were made on the pessimistic side.
An earlier Gabriel
estimate was that the number lay in the interval 20 megatons to 90,000
megatons,.
There was considerable discussion about details of the calculation
Sunshine and the conclusions.
Discussion
Among the points brought up were the following.
Biological concentration in ¢ertain types of plants may lead
to a special hazard.
The amount of strontium in Japanese individuals is greater than
the amount for occidentals; thus, the hazard to the Japanese may be
greater,
The tolerable figure of one microcurie of Sr-90 per person was
arrived at by the International Commission on’ Radiological Protectior
and is based on radium experience.
One microcurie of Sr-90 (0.54
Mev betas) was taken as biologically equivalent to one-tenth microcurie of radium ("6 Mev alphas").
Carcinogenic effects are observed
with radium at one microcurie per human.
(Secretary's note:
how
valid the quantitative figure for Sr-90 is, and just what significance should be attached to it seem at present unclear.)
Dr. Wigner was especially concerned about the cffccts of
inhaled insoluble particulates, on the ground that if radiation
originates from one point it is more likely to start cancer than if
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it is distributed uniformly (because of the high radiation density