only after hundreds of rep were accumulated and tumors only after
1500 or more,"
The permissible level referred to is that recom-
mended by the NCRP for industrial workers, The Committee noted
that although "some children have accumulated a measurable amount
of radioastive strontium in their bodies, the amount is quite
small--a thousandth of what is considered a permissible dose,
Committee concluded, "then, that Strontium-90 is not a current
The
threat, but if there were any substantial increase in the rate of
contamination in the atmosphere, it could become one."
Committee on Metesroiogizal Aspects of Atomiz Radiation
Chairman - Harry Wexle> ~_U, S, Weather Breau
In this part of the report there is the fullest discus-
Bicn of fallout from nuclear weapons, They distinguisn between
kilcton burats when the cloud does not penetrate to the stratosphere ard megaton bursts where the zloud does, They estimate
that with surface bursts, i,e,, whare the firebali touches the .
ground 70-80% of the residuel radisastivity falls ozt nearby, i.e.,
with small weapons a few miles, with larger cnes up to 300 miles
or more, They emphasize the ease of predicting this "nearby" fallout pattern after the fast and the problem of predicting its precise pattern prior to detsnation,
They speak of intermediate fallout, i.e., material of
small particle size released below the stratosphere and some 80%
of which falls cut within three
which it originated and tending
with rainfall and wind patterns
general latitude as that of its
weeks in the same hemisphere in
to uneven distribution associated
along a broad band in the same
origin, Finally, they refer to
delayed fallout cf materiel whish has gained entry into the strato-
sphere,
It is slow with an average storage time in the stratosphere
of 10 years, plus or minus five years, AEC believes the latter
\
figure - five years - is the more likely,
This delayed fallout
tends to distribute itself more or less uniformly over the surface
of the earth over the years.
NAS
They state that "at present, the amcunt cf Sr 90 in the
stratosphere from nuclear weapons tests is far too small to approach
maximum permissible concentration even if it were all deposited now,"
They urged a continuing pregram to check on the amount of radioactivity in the stratosphere as necessary so that if there were to
be a greatly increased rate of thermonuclear weapons testing activi-~
ties we would know at the earliest moment when it was time to slow
down in terms of potential hazard from Sr 90 to man,
There is also a discussion of the radicactivity from fall-
out of the intermediate and delayed varisty.
They point out that it