The experimentsat Eneu Island at ikini Atoll
significance of the four radionuclides via the
using potassium-rich fertilizers (1qN-16P-16K)
or KC, show a reduction greater
10 fold in
the concentration of 137Cs in cocon$t meat and
fluid; the 197Cs concentrationsin f
ingestion pathway (Table 18). The MAI for
Rongelap is the maximum annual intake that
would occur based on the model described
reviously. For example, the intake of 137Cs
would be less in any year after 1995 decreasing
exponentially by the 30-y radioactive half-life
0.74 to 1.5 Bq g-! (20 to 40 pCi g-1)
workers as defined by the ICRP, is that annual
using potassium-rich fertilizer ar
(i.e., 2.3% per year). The ALI for occupational
while the 137Cs concentrations in
intake of each radionuclide that would lead to
an effective dose of rate
20 mSv y—!
(2000 mrem y-!). In Table 18, we have reduced
the ICRP ALI for occupational exposure by a
factor of 20.to correspond to the adopted annual
guideline of 1 mSv y—! (100 mrem y-!) effective
dose rate for the public. As indicated in Table
Eneu Island, we
fe began a similar ex
the adjusted ALI; it would of course decrease
are about 8 to 10 times higher
Bikini Island where the 137Cs conc
18, the MAI on Rongelapfor 137Csis about 22% of
with each succeeding year. On the other hand,
Island. The results of that experi
9S, 239+240Py, and 241Am are only 0.57%, 0.22%,
and 0.17% of the ALI, respectively.
weight to about 0.56 to 0.
(15 to 20 pCi g-!) wet weight. In
Mitigation of Food-Chain Dose
wherethe initial concentration was
We have conducted many experiments at
etween 1.9
to 3.7 Bq g-! (50 to 100 pCi g-!) wet weight, the
potassium treatment has reduced [the 137Cs
Bikini Atoll to evaluate methods to mitigate
concentration to less than 0.37 Bq g-! (10 pCi g-}).
eee ce nH
the 137Cs dose from the terrestrial food chain.
Table 18. Comparison of the maximum annual intake (MAI) on Rongelap Island with the sifted ICRP
annual limit on intake (ALI) for 137Cs, ®Sr, 39+240Py, and 241Am.
Nuclide
B7Cs_
Sr
MAI on Rongelap@
Imported foods Imported foods
available
unavailable
(Bq)
(Bq)
1.1 x 104
1.7x 102
2.8 x 104
Adjusted
ICRP ALIb
(Bq)
5.0 x 104
5.5 x 102
3.0 x 104
MAI asia fraction
of the ALI when
imported
foods
are avdilable
0.22
0.0057
239+240Py (ingestion)
4.4
11
2.0 x 103
0.0032
241Am (ingestion)
2.6
4.7
1.5 x 108
0.0047
239+240Py (inhalation) 0.037
0.037
15
.
0.0035
241Am (inhalation)
0.028
0.028
15
0.0099
a Maximum annual intake based on data and models described in text. This value becomes legs each
year, declining exponentially with the 30-y half-life of 137Cs (2.3% per year).
b The ICRP ALI (ICRP, 1991b) is divided by 20 to adjust the ALI, which is based on an effective dose of
20 mSv y-! (2000 mrem y-1), to a general population ALI based on aneffective dose of mSv y~!
(100 mrem y-!) (ICRP, 1991a; NCRP, 1987b).
35