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August 2010, Volume 99, Number 2

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Fig. 4. Annual doses (mGy) to thyroid due to chronic intake of residual radioactivity in the environment from fallout
for Majuro and Kwajalein residents, and for Utrik and Rongelap Island community members, born in three different
years: 1930 or before, 1953, and 1957. Doses for Utrik and Rongelap community members accountfor relocations (see
Simon et al. 2010, Table 3). Note different y-axis scaling of each panel.

the equivalent doses from chronic intakes of *’'™°Pu
represented less than 1% of the total internal doses
from chronic intakes; and

"Bi: Along with “Co and '°’Cs,Bi wasone ofthe

three radionuclides that were detected with regularity
in gamma spectrometry analyses conducted until the
mid-1990’s (Noshkin et al. 1997). A summary ofall
the available data on the concentrations of *”’Bi in
flesh samples of reef and pelagic fish collected from
Bikini and Enewetak Atolls between 1964 and 1995
was published by Noshkinet al. (1997). Their analysis

showed that: (1) the highest **’Bi concentrations, by

far, were observed in goatfish, which is representative

of reef fish, (2) at Enewetak Atoll, “Bi was lost from

the environment with an effective half-time of 5.1 y,
whereasat Bikini Atoll, only radioactive decay, with a
half-life of 32.2 y, accountedfor the rate at which *”’Bi
was disappearing from the lagoon, and (3) representa-

tive concentrations of *’’Bi in goatfish flesh in 1978

were 8.1 Bq kg! at Bikini and 241.9 Bq kg' at
Enewetak. Assuming, here again, that all of the radioactive contamination of the lagoons occurred in 1954,
the time-integrated concentrations of *°’Bi in goatfish
flesh from 1954 to infinity were estimated to be 630
Bq y kg' at Bikini and 46,000 Bq y kg' at Enewetak.
Using an assumed daily consumption of 43 g of reef
fish (Robison and Sun 1997), these time-integrated
concentrations lead to lifetime doses to adults that

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