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Health Physics
The combination of the assigned uncertainties to the
components of the thyroid dose to representative adults
of the Utrik community, due to intakes of '*'T and !*I
from the Bravo test, results in an overall uncertainty
(GSD) of 2.4.
As was the case for the members of the Rongelap
Island community, the other components of the thyroid
dose received in 1954 by members of the Utrik community (acute intakes of other radionuclides, chronic intakes
of long-lived radionuclides, acute and chronic intakes
from tests other than Bravo) are small, but much more
uncertain. Even though these additional components
havelittle influence on the overall uncertainty, the GSD
of 2.4 estimated for the thyroid dose from Bravo was
modestly increased to 2.5 to represent the uncertainty in
the thyroid dose received in 1954 by members of the
Utrik community. Again, as for the northern atolls, we
assume that the uncertainty in the dose to other organsis
comparable to that we estimate for the thyroid. We also
assume the same uncertainties for years other than 1954
since, even though the uncertainty in deposition varies
from test to test, the uncertainty in Q/D should not have
differed significantly.
Population groups in the mid-latitudes and in the
southern latitudes
In the mid-latitudes and in the southern latitudes, the
internal doses are much smaller than those for the
Rongelap Island and the Utrik communities and the test
with the largest contribution to the doses was not Bravo,
but rather Romeo, Koon, or Yankee, all of which took
place in 1954. Our estimate of uncertainty in internal
doses to residents of mid-latitude and southern latitude
atolls is again based on the estimated uncertainty in the
acute thyroid dose dueto intakes of '*'I from a particular
test in a specific atoll, in this case, from the Romeotest
by an adult representative of the Majuro residents.
The thyroid dose to adults from acute intake of
from Romeo can be expressed as:
1317
D('?'T, Romeo, adults) = Dep('*’Cs, Romeo)
Dep('3'I, Romeo)
QO(!?'I, Romeo)
Dep('*’Cs, Romeo)
Dep('3'I, Romeo)
August 2010, Volume 99, Number 2
this term is a minor contributor to the overall uncertainty
and, thus, can be neglected.
Uncertainties in O(''T, Romeo)/Dep('"'I, Romeo):
The uncertainty in Q/Dep depends on the validity of the
assumption that the ratio of the acute intake and of the
deposition density of '°'I at Majuro for a TOI of 140 h is
the same as the ratio that would have been obtained at
Rongelap for the same TOI value. Because there were no
bioassay measurements of '*'I from which the intakes of
the Majuro residents can be readily derived, the uncertainty in the best estimate for Q/Dep at Majurois clearly
greater than that at Rongelap or Utrik. Deposition would
have continued for much longer times and beenlikely
influenced by both wet- and dry-deposition processes.
Also, for these distant atolls, fallout particles would be
considerably smaller, although still, based on the mete-
orological modeling described in Moroz et al. (2010),
generally >10—15 um in diameter. Thus, there is considerable uncertainty about the magnitude and pathway
of the intakes following individualtests. It is likely that,
for sometests, muchof the fallout took place during the
frequent occurrences of heavy rainfall in the south.
Consequently, the skin of the residents, as well as the
cooking utensils and the foodstuffs, were probably not
contaminated to the degree that may have occurred from
dry fallout of very large particles at Rongelap. Inhalation
doses would, thus, still likely be relatively minor com-
pared to ingestion, particularly when the fallout occurred
during rain. Thus, the GSD for Q('*'I, Romeo)/Dep(*"'l,
Romeo) at Majuro was taken to be 2.5, which is
substantially greater than the values of 1.6 and 2.0 that
were determined for the GSD of Q('*'I, Bravo)/C(1"'1,
Bravo) for Rongelap and Utrik, respectively. Finally, the
uncertainties in the doses per unit intake, D/O, at Majuro
were taken to have the same value of GSD (1.4) as for
Utrik.
The combination of the assigned uncertainties to the
components of the thyroid dose to representative adults
at Majuro due to intakes of '*'I from the Romeotest
results in an overall uncertainty (GSD) of 2.7. However,
contrary to the situation at Rongelap and Utrik, more
than one test contributed substantially to the 1954 thyroid
dose. The tests Koon and Bravo contributed about as
much as Romeo, while Union and Yankee accounted for
(17)
much smaller '*'I intakes (see Table 9, Simon et al.
2010). Because the uncertainty assigned to the deposition
Uncertainties in Dep('’’Cs): The '°’Cs deposition
low (GSD = 1.3), the choice of another test could have
, D(31))
o('3!T)’
density resulting from the Romeotest was estimated to
be 0.7 kBq m* (Becket al. 2010) with an uncertainty
(GSD) of 1.3.
Uncertainties in Dep('*'I, Romeo)/Dep('*’Cs, Romeo): As discussed above for Utrik, the uncertainty in
of '’Cs from the Romeo test at Majuro wasrelatively
resulted in an overall uncertainty (GSD) greater than 2.7.
For example, an overall uncertainty of 2.9 would have
been obtained for Koon, as the uncertainty in the '°’Cs
deposition density for Koon at Majuro (GSD = 1.5) is
greater than that for Romeo. For Yankee, with an even