tained inside insoluble particles, the calculation given below should then be regarded as highly pessimistic”.... (1.e., that the estimate of fission yield to create a world-wide hazard may be too low.) "h, Availability of natural etrontium in soils. "The parameter used here is 60 lb. of agriculturally available strontium pey 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 20 times this amount. Having used the lower limit, our estimate in this respect is also pessimistic”.... {i.e., too low.) "S. Redistribution of strontium-90 by plowing, fertilizer, etc. "Fall-out debris deposited on wuntilled soil is not leached down very effectively by rainfall. In agricultural areas +-e. however, the soil is constantly well mixedto an effective depth by the efforts of man. wash-off as relatively low. We also assume These considerations do in themselves...." {further tend to make the fission yield value calculated too low.) "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 .... accurate. “On the basis of the above assumptions and other physical parameters,the preliminary SUNSHINE estimate of the nuclear bomb.... {fission) .... yield required to bring the population of the world up to Maximum Permissible Concentration is larger than 2.5 x 10+ megatons "The .... formula for arriving at the above figure is as follows: