“i
DISCUSSION
The body-burden and urine data indicated a
Ghat
(nha
CHL LB
definite decline with ume from the dayof return
atom ingestion rate for "Cs. °Zn. “Co and
citgy
indicated a decline. These measurements of in-
t
1
ak
a
rauo
“Sr. The data for “’Pu were uncertain but
MAR OUR be
The,
OMAR Th be
idard
clive
yk
2e k's
Se nee nme ee
ntro. with
adult
“Fe.
diet. The data for directly measured bodybur-
adult
Jatea
Fig. ~. Exposure-raie hrivory at Rengelap Atoll.
GUBR ACE
on this ingestion rate, it was estimated that “Fe
ghee hi t
ME Tee OOve
ot
adult average body burden for each atoll. an
78
xD YoRE
the}
al
TAME BLT So-AB ToT Uy
- pe“185.
mes
2hr
they
10°
ind,
Fic. 8 Exposure-rate history at Uumk Atoll.
These values were based on the exposure-rate
history for each island and do not include the
exposure contribution before rehabitation or
from natural background radiation. The back-
4). The assumption that & = 0 for “Fe was made
because sequential body-burden data were not
available. Assigning k =2.0 x 107?d7'. the
value determined for “Co. leads to an “Fe
committed effective dose equivalent of
23x 107°Sv (23x 107'remi for Rongelap
adults. This is larger by a factor of 5 than the
estimate for committed effective dose equivalent
based on k = 0.
Use of the body-burden extrapolation equa-
tion leads to the conclusion that * Zn could have
been the major contmbutor to the ingested
activity during thefirst year post-rehabitation of
Utink Atoll (see Table 4). This was supported
to
9.6x 107 'nCkg7' ho!
photon count rate at the surface of various types
of tuna retrieved from the Marshall Islands’
fishing grounds from March to August 1954
(100-10,000 cpm). Fish with count rates greater
enberger and Greenhouse (Gr77b) and was
Atoll
valeral
The 50-yr external effective dose equivalent was
to
nearly natural background levels by the year
ind.
contributed a negligible amount to the total
committed effective dose equivalent (see Table
ground exposure rate was measured by Milt-
h =~]
the
rom
8).
subwas
and
dens at Rongelap Atoll were the best qualitv
data for determining derived quantiues.
Based on a declining continuous intake due
solely to radioactive decay and the 1970 “Fe
esumate of the daily activity ingestion rate for
“Fe on the dav of return was calculated. Based
ty Alp
ato utd
é
SUR AL F
i
atec
itted
«
even
TORE
rbed
FXENIGLIGE
vf an
hese
OAT ONE ME TRAE ABONE
a
chides
amu‘lude
1cer. fa-
tron with the declining continuous intake equa-
the committed effective dose equivalent and the
rate of deciine of radionuclides in the overall
i
ividSr,
ternal Jeveis of radionuclides used in conjuncuions provuiec an esumate of the total intake,
er I
id P
corr.
523
E. T. LESSARD erul.
(3.7 x 107° Rh7!).
estimated to be 1.7 x 107? Sv (1.7 rem) at Rongelap and 4.1 x 10~?Sv (4.1 rem) at Utirik. The
external exposure rate is expected to decline to
2072.
Theratio of internal committed effective dose
equivalent to 50 yr of net externa! dose equivalent was 1.1 for Utink and 1.5 for Rongelap.
The internal portion of these dose equivalent
ratios does not include the contribution from
Pu due to the uncertainty in Pu bioassay data.
201 2b 14
some
extent
by
a
Japanese
report
(JCCRRER56) which indicated a rise in the
than 100cpm at the surface were discarded.
Radiochemical techniques indicated the prominence of Zn in the tuna’s edible flesh. If it was
assumed (1) that ©°Zn was the principal con-
tributor to the externa] photon count rate, (2)
that a self-sufficient living pattern existed on
Utirik in which adults consumed 300 g of fish
each day (Na80), and (3) that 1% of the fish
eaten was tuna, then the daily activity ingestion