Table I
Ratio of Doses
the Two Modes of Intake
Inhalation
|
' 133
for
135
I,
fiji,
Oral Ingestion
L,
(131,
133
I
/131,
135
I;
131,
Decay
0.68
0.31
0.487
0.148
Fission yierg 6? |
1.38
1,23
1,38
1.23
Energy
2,00
1.50
2.00
1.50
1.85
0.57
1.35
0.27
Net Factor
The dose to the Fhyroid in rads from all three isotopes is, rays, 3.4 times
the dose due to
IT alone for inhalation and 2.6 times the
I dose for oral
ingestion.
Delay in reaching the thyroid atts inhalation or ingestion,yguld
lower these factors somewhat.
However, the
I daughter of the 78, 8%
Te
bas been neglected and would approximately compensate for decay of
I and
I before reaching the thyroid.
We can now proceed to estimate the dose to the thyroids of 3 - 4 year
old girls assuming (1)
inhalation as the mode of intake and (2)
of Oxy agn intake
(b)
oral ingestion.
1,
Inhalation:
The ratio of volume of air respired by a 3 - 4 year old girl
to that of an ady
can be estimated in two ways:
(ea) from the maximum rate
and
from the vital capacity
and maximum respiration
rate,
Both methods give a ratio of 0.3.
The thyroid burden of these
children would then be 3.4 uc with a range of 1.7 - 6.8 uc.
Assuming the Rongelap children are similar to those of New York (9)
children, the mass of the thyroid of the children is 2.5 + 0.6 grams.
The most probable dose from 131, is then 150 rad and the dose from all
isotopes is 510 rad.
If we consider the range of thyroid burden (1.7 - 6.8 uc)
and the variation in thyroid weight (1.9 - 3.1 gms), the dose is in the range
of 200 - 1350 rad.
2.
Oral Ingestion:
At the time of the event the Rongelap people were on a
water ration of one pint per day.
They were warned not to drips water after
the event but most of them admitted they drank water anyway.
The method
ot collecting water by runoff from roofs into cisterns makes it very likely
that this was the main source of oral ingestion. There are reports that it
“rained a little’ on the afternoon of March 1 (D-Day).
The village doctor
reported that the "water turned yellow.'"' As far as food is concerned, the
most
likely source is dried fish.
Fish were dried on open racks.
However,
in the interviews none of them listed dried fish as having been eaten during
3]
bate
2008365