-3-
-2-
If we assume a Inear buildup of fallout from H +8 to H + 18, ¢7)-4
decay during this interval, and use the reading of 375 mR/hour at 7 daye,
Experience from
Sedan indicates that the dose from the cloud itself is approximately equal to
{Ouax.
nao all
the dose from fallout during cloud passage.
The total estimated dose ia then
47 +47 +114 = 208 R.
Within the error of the measurements and the accuracy of the assumptions, this estimate, which does not contain any correction for the small
effect of time indoors, does not differ significantly from the value of 175 R.!
We will, therefore, take the average whole-body gamma dose as 175 + 25 R.
Res| en ~see_iapeeaieeneetlinamm Rann mn om
Unfortunately, no direct measurement was possible on the radioactive
which the average thyroid burden of
Urine samples were taken from
se has been estimated.
The Los Alamos
Scientific Laboratory collected pooled 24-hour samples 15 days post-detona-
tion and estimated” the 1-day thyroid tontent as 11.2 nCi of 271. usNRDL
collected samples from each member of the exposed group 43 and 46 days
post-detonation and, by an indirect method, estimated the average thyroid
AdOou
i\Ouax }
4.8
1
4,829
20,1
al
18,011
75.0
>16
Volume
The urine samples are typical of adults and the calculated thyroid burdens
are presumably also those of adulta.
Associated with this yp4} are the shorter-lived isotopes p33 33
and 235.
If the iodine entered by wayof inhalation, the time of intake was
H+6toH +18.
On the other hand, if water (and food) were the principal
source, the time of ingestion would be extended from H + 6 to H + 51.
iodine isotopes.
These are:
average energy deposited in the thyroid per disintegration.
are presented in Table I for 1333 and 135
distribution in the cloud was assumed.
These factors
In the case of inhalation, uniform
For oral ingestion it was assumed
that, on the average, one-third of the intake occurred at H + 10 and two-
thirds at H + 30.
Table I.
Ratio of doses for the two modes of intake.
Inhalation
The value of 11.2 wCi will be used as a basis for
This estimate was based on the assumption of
(1) radioactive decay before inhalation or oral
ingestion, (2) differences in the fission yields of the chains,® and (3) the
obtained by direct counting of y3h in the urine and should be more reliable
all following considerations.
1,155
5-16
content as 6.4 pCiT!9! at 1 day.) * The LASL estimate of 11.2 pCi was
than the NRDL estimate.
7
<6
Three items contribute to the differences in dose from the various
Internal Deposition of Iodine Isotopes
iodine content of individuals from Rongelap.
% of Total
Urine (ml)
Oral Ingestion
y2337,131
p55),131
133),131
p35, 351
Decay
Fission yield®
0.68
0.31
0.487
0.1% of the maximum thyroid burden being excreted in the urine on the 15th
day.
Energy
2.00
1,50
2.00
1.50
1.85
0,57
Se
0.27
Variation in the biological half-life and other factors indicate that a
range of 0.05 to 0.2% should be placed on this number” (see appendix).
We,
therefore, take 5.6 to 22.4 wCi as the range of adult ps! thyroid burden.
The pooled samples represent all age groups.
The number of
individuala in these age groups and the volume of urine from each age group
is approximately as followa: ‘ 4
Net Facior
1.38
1.23
1.38
0.148
1.23
*
The dose to the thyroid in rads from all three isotopes fa thus 3.4 times the
dose due to ysl alone for inhalation and 2.6 timea the 31 dose for oral
ingestion.
Delay inreaching the thyroid after inhalation or ingestion would
lower these factors somewhat.
However, the 333 daughter of the 78-bour
Te? has been neglected and would approximately compensate for decay of
133 gna 1335 before reaching the thyroid.
We can now prgceed to estimate the dose to the thyroids of 3- to 4year-old girls assuming (1) inhalation as the mode of intake and (2) oral
ingestion,
Tee ee eee eet eer ees ne
eafnet hs
the fallout from H + 18 to evacuation at H +51 is 114 R.
The dose from
Volume of
Individuals
ee
the estimated dose from fallow during cloud passage is 47 R.
Number of
Age Group