S16
PROTRACTED EXPOSURE TO FALLOUT
ree
3
|
iA¢
f
1
$
6575
{xy
tissue of interest per nC kg’ (0.73 rad-R} mea-
sured in air at | m above the surface was usec
to convert their data to absorbed dose in Llissue.
This factor was based on several considerations.
First. the planar source represented by the flat
atol] was assumed to be an exponentiai distribution of “Cs activity with depth in soil. typica!
6065
Heiter
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fa HER a
r
y
a
o
ae
'
their reports (Ch60: He65: Gr77b. JCAES”.
TiSl: USPHSS9). A vaiue of 2.8 x 10>" Gyin
r
explanation of their metnods can be found in
? Fatal
External radiation exposure
The external radiation exposure rate data
were Measured by man\ individuals and an
fty
ployed to obtain adult average standard deviavons for k and P .
S5Pe
905r
Fic. 2. Cesium-137 body burden fer Rongelap adults.
of aged fallout (Be70)}. The nature of this source
caused minimal] variation of absorbed dose with
depth of organ; however. the difference tn the
number of electrons per gram of air and per
gram of tissue necessitated a correction. Secondlv. since the atolls presented a varving exposure rate environment. absorbed dose was
adjusted for living pattern variations. Both of
these considerations combine to give the above
HoneT
Body burden data and urine activity. concertrations
The average body-burden data for adults
since their return to Rongelap and Utink Atolls
are presented in Tables } and 2. In these tables,
the zero day or day of return for Utink was
nearly 1000 days before the zero day or day of
return for Rongelap. Directly measured body
burdenswere listed for Co. “Zn and '°’Cs. For
"Cs. an initial rise in body burden and a
subsequent general decline was apparent. These
data were plotted in Fig. 2 along with their
standard deviation and standard error.
Conversion of adult average ”Sr and *Pu
body burden for these nuclides. Average data
were listed in Tables | and 2 and plotted in the
case of *Sr (see Fig. 3). The body burdenslisted
for *Fe were obtained from Beasley (Be72). The
901 Zbb 1
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Ft = RONGELAP ADULT MALE
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Measu:
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4
4
2
urine activity-concentration data was done as
indicated in the methods section to derive a
i STANDARD DEVIATION &
60% OF MEAN
oO w
RESULTS
|
HE aan ba
—
factor used to convert external exposure to
absorbed dose in tissue. Specific details on the
adjustment for living pattern vanation were
given by Miltenberger and Greenhouse (Gr77D).
1
cnt ne y+
Oo 73 ~
f
O
°
@
é
g
a
=
n
e
LLL bi lip tii bli fe th
2.7
—_
1600 3200 4600 6400 8000 9600 11200
TIME PAST REHABITATION, days.
Fic. 3. Strontium-90 urine activity excretion rate for
Rongelap adults.
methods
blood m
The r:
available
ysis of th
age bod}
from 40
comparis
atoll wh: