RMI Nuclear Justice Documents

Internal Deposition of Iodine Isotopes
Unfortunately, no direct measurement was possible on the radioactive

iodine content of individuals from Roggelap.

which the average thyroid burden of

Urine samples were taken from

I has been estimated.

The Los Alamos

Scientific Laborateny collected pooled 24-hour samples 15 days, gost detona-

tion and estimated

the l-day thyroid content as 11.2 ue of

I

USNRDL

collected samples from each member of the exposed group 43 and 46 days post
detonation, and, by an ingiregt method, estimated the average thyroid content

as 6.4 uc
I at Ligey°
The LASL estimate of 11.2 ue was obtained by
direct counting of
I in the urine and should be more reliable than the
NRDL estimate.
The value of 11.2 ue will be used as a basis for all following considerations.

This estimate was based on the assumption of 0.1% of

the maximum thyroid burden being excreted in the urine on the 15th day.
Variation in the biological half-life and other, factors indicate that a range
of 0.05 - 0.2% should be placed on this number
(see folfowing section by Ng).
We, therefore, take 5.6 - 22.4 uc as the range of adult
I thyroid burden.
The pooled samples represent all age groups.

The number of individuals

in these age groups ,ang the volume of urine from each age group is approximately as follows:
*~’

Age Group

<5

5 - 16
> lo

Number of
Individuals

Volume of
Urine(ml)

7

1155

1l
31

4829
18011

% Of Total
Volume

4.8
20.1
75.0

The urine samples are typical of adults and the calculated thyroid burdens are

presumably also those of adults.
135

Associated with this t31, are the shorter lived isotopes 132)

1335 and

I.
If the iodine entered by way of inhalation, the time of intake was H + 6
to H +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.
Three items contribute to the differences in dose from the various
iodine isotopes.
These are:
(1) radioactive decay before inhalation, or
oral ingestion, (2) differences in the fission yields of the chains,
and (3) the average energy deposited in the, thyroid Pst disintegration.
These factors are presented in Table I for
I and
I.
In the case of
inhalation,

uniform distribution in the cloud was assumed.

For oral ingestion

it was assumed that, on the average, 1/3 of the intake occurred at H + 10 and

2/3 at H + 30.

80