a.
gastrointestinal tract, from the gross fission product
b.
thyroid, from isotopes of iodine, and
ce.
bone, principally from isotopes of strontium and barium-
activity,
4
%
.
lanthanum.
a
.
4
'
The solubility of the fallout material is a major factor in determining
the resultant fate, and thus radiation doses, within the body.
The solubility
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 about 21 months after the March 1, 1954 fallout,
was found to have about 80 percent of the activity in the filtrate, but
there was an undetermined amount that settled to the bottom.
Other data
suggest the material to have been about 10-20 percent soluble in water.
Figure 7 shows relative doses to the body organs, based on the
assumptions that (a) 90% of the material is insoluble (when calculating
doses to the gastrointestinal tract), (b) all of the isotopes of iodine
are soluble (when estimating doses to the thyroid), and (c) 25% of the
ingested strontium isotopes and 7% of the barium—lanthanum reached the
bones.
It may be seen that ingestion of a given amount of fission product
activity on the fourth and fifth days may result in nearly two and one-half
times the dose to the thyroid as to the lower large intestine.
For a con-
timuous consumption of fallout material from the first hour to the 30th