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fission products in fallout, namely Strontium-90, they stated
"there seems to be no reason to hesitate to allow a universal
human strontium burden of 1/10 of the permissible yielding 20
rep in a lifetime,....
Visible changes in the skeleton have
been reported only after hundreds of rep were accumulated and
tumors only after 1500 or more,"
The permissible level referred
to is that recommended by the NCRP for industrial workers,
The
Committee noted that although "some children have accumulated
a measurable amount of radioactive strontium in their bodies,
the amount 1s quite small~--a thousandth of what is considered
a permissible dose,
The Committee concluded, "then, that
Strontium-90 is not a current threat, but if there were any
substantial increase in the rate of contamination in the
atmosphere, 16 could become one,"
Committee on Meteorological Aspects of Atomic Radiation
Chairman - Harry Wexler - U, S, Weather Bureau
In this part of the report there is the fullest discussion
of fallout from nuclear weapons,
They distinguish between
kiloton bursts when the cloud does not penetrate to the strato-
sphere and megaton bursts where the cloud does,
that with surface bursts,
They estimate
1.¢e,, where the fireball touches the
ground 70-80% of the residual radioactivity falls out nearby,
i,e., with small weapons a few miles, with larger ones up to .
300 miles or more,
They emphasize the ease of predicting this
"nearby" fallout pattern after the fact and the problem of
predicting its precise pattern prior to detonation,
They speak of intermediate fallout, 1,e., material of
small particle size released below the stratosphere and some
80% of which falls out within three weeks in the same hemisphere
in which it originated and tending to uneven distribution
- 10 -
Enclosure II.