SLIDE 21
Radioactivity intake estimated from excreta. The fraction of an initial 131;
activity intake by ingestion that would be eliminated by an adult on a given
One was a model by Johnson
day post the intake was calculated by two methods.
(Jo81) and the other was a model used by ICRP (ICRP79). Both models had
feedback incorporated into the estimate of the fraction of initial intake.
Both were solved using catengry compartment kinetics and both led to similar
I by a reference man. Based on 0.48 kBa (1.32 x
valyes for elimination of
10°“ #Ci) in adult urine
intake was estimated for
18 I.the
17th day post intake, a 3,440 kBq (93%
lang
Ci)
The intake of 3,440 kBq (93 s# Ci) Yas used as a normalization point.
That is, once the relationship between
I and other nuclides in fallout was
determined by us, then the contr} bytion to thyroid dose from all radioiodines
was estimated while keeping the
I intake at 3,440 kBq (93 BCL).
Whole-body retention functions were given by ICRP (ICRP72) for strontium
and barium as follows:
=5
-4
Rg(t) = 0.60082540 ,299(£40.20)-0+18(0, 555¢76+ 5x10” tag gu5en2eOx107 Mt,
_
_
4
_
“4
Rya(t) = 0.38e0°7 940.191 (t+0.007)70*237(0, 56407! 20910 “tay 436074 36x10 ty |
where t is in days and R(t) is the absorbed fraction remaining on day t.
The
fecal to urine ratios for excretion of absorbed Sr and Ba wer 0.25 and 9.0,
respectively (ICRP72) Correcting for45 days of decay, the 125 activity
absorbed was estimated to be 2.3 x 10° Bq (0.62 pCi) and the
Ba activity
absorbed was 6.1 x 10° Bq (16.4 Aci). If fallout was directly ingested as a
single intake of dust at 0.5 days post detonation, then the intake of 140
905, or L3ly should be in a ratio similar to one estimated by us by a
different approach.
The fraction of ingested iodine absorbed into blood was
taken as 1.0, the fraction of ingested strontium absorbed into blood was taken
as 0.2 and the fraction of ingested barium absorbed into blood was taken as
0.06 (ICRP68} 4 The tR5ake ratios we obtained from urine results for
I
relative to
~*Sr or
Ba are 28 and 0.34, respectively. The hypothetical
ratios are 8.5 and 1.2 based on unfractionated thermonuclear fission data.
Thus the urine derived patio of activity is a factor of 3, kewer than the
hypothetical ratio for
Sr and a factor of 3 higher for
ESTIMATE OF ACTIVITY INGESTED
(RONGELAP)
Nuclide
Activity
Iodine Activity®
Bq
Nuclide Activity
Ingested
ae
a9
3.4x10°5
Ba
1.0x107
Sr
1.2X10
et
1.0
8.5
1.2
*Thermonuclear neutron fission and 5 hours
post detonation.
26
Ba.