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Graph Five) to lower the doses to the gastrointestinal tract.
Thus, having
selected the amount of intake of fallout material principally according to
thyroid doses, the doses to the gastrointestinal tract and bones were calculated according to Sections I and III and plotted as shown in Graph Five.
Then, Graph Four was used (after correction for the first day and after
UT
STE
wile ve
the 10th day as described above) in preparing Table Three for prolonged
intake periods by taking the values at the midpoint of these periods, except
for the cases where the midpoint fell after about the 10th day when the
value was held to 11 microcuries.
This selection of activity values at
the midpoint of an intake period obviously introduces errors but the
uncertainties of times and amounts of intake precludes precise estimations.
V.
A.
Discussion
Solubility
In calculating doses to the gastrointestinal tract it has been
absumed, as the limiting case, that all of the fallout material is insoluble.
The solubility of fallout material varies, depending among other
factors upon the surface over which the detonation occurred.
The fallout
material collected in soil samples at the Nevada Test Site has been quite
insoluble, i.e. only a few percent in distilled water and roughly 20-30
percent in 0.1 N HCI.
However, it would be expected that the activity
actually present in drinking water supplies would be principally in
soluble form.
The water collected from a well and a cistern on the
Island of Rongelap (Table Four) about 21 months after the March 1, 1954
fallout, was found to have about 80 percent of the activity in the
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~8-