terms of the conditions likely to be encountered in the field as was
the case for the accidental human exposures at CASTLE.
If in the case of the first CASTLE shot, the instrument readings in milliroentgens per hour at 7 to 9 days post-shot are extrapo-
lated back to shot day and the value thus obtained integrated over the
period of exposures using the + f decay law, the values obtained
compare favorably with dosages that would be estimated on the basis of
the biological responses observed.
The problem of measurement is not ©
so simple and it seems possible that there may be factors omitted from
the oversimplified estimation procedure just cited that would tend to
lower the values obtained.
Among these are:
(1) The travel time of fall-out, which may vary from estimates
made.
(2) The gradual build-up of fall-out, which makes determination.
of a single “arrival time" uncertain.
(3) The shielding effect of special environmental conditions,
such as buildings, trees, and clothing.
These might be counteracted by other factors not directly considered
which would tend to raise such a value:
(1) The geometry of exposure.
(2) The adhering of particles to clothing and skin.
(3) Increased intensities below the 3 foot measuring level.
(4) The biological recovery factor in prolonged exposure
times.
Thus a cancellation of errors may permit by a fortunate coincidence the
use of a simple straightforward calculation to obtain a quite valid
estimate of the dose involved.
The temporary epilation in the Marshallese suggests the dose
to exposed skin on Rongelap was approximately 10,000 rep of beta radiation.
Because of evidence of completely intact skin under clothing,
the dose to the protected skin was probably less than 5000 rep.
Thus
the CASTLE data suggest that the clothing worn by exposed persons pro-
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