rediation rates in a fall-out field at times from five minutes to about
one year after burst time.
The body is known to recover from at least a major portion of
sublethal damage due to ionizing radiation.
The rate of repair is wn-
known, but is believed to be of the order of 10% per day of the reparable
damage remaining.
Lethal dose estimates are well within the limits of
the accuracy of the physical data upon which they are based.
In a fall-out area where the gamma radiation dose is sub-lethal,
fission product beta and soft gamma emitters in the fall-out are a
serious hazard only when in contact with the skin.
A high degree of pro-
tection against this type of radiation is afforded by clothing which
prevents fall-out material from contacting the skin.
There is a need for a high yield land-surface test detonation
to fill in uncertainties in the present fund of knowledge on fall-out.
(v
The primary long-term and world-wide hazards arise from the
distribution by winds in the upper atmosphere of certain cancer-forming
radioisotopes produced in the fission process, and their subsequent
biological uptake by humans.
Prominent among these are strontium-89,
strontium-90 and iodine-131.
Approximately one gram each of strontium-89, strontium-90 and
dodine-131 is formed per KT of fission yield.
Because of fractiona-
tion, these elements are produced in such form and quantity as to favor
their world-wide distribution as opposed to local deposition.
However,
for surface bursts the local contamination still remains the dominant
factor.
The potential genetic effect of fall-out radiation on man is
likely to be secondary in importance to short-term effects as well as
to the hazard due to long-term cancer-producing effects)
The chief
uncertainties in this regard lie in the extrapolation of animal data
to man.
The manner of expression of the bulk of such radiation-
induced mutations is, likewise, not certain.
If manifested as miscar-
riages, this would greatly reduce the possible burden to society involved.
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