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Acute and chronic intakes of fallout radionuclides @ S. L. SIMoNn ET AL.
Table 7. Parameters used to estimate '*'I and '°’Cs intake among adults based on urine bioassay (Harris et al. 2010)
following the Bravo test and '*’Cs intake per unit ‘Cs deposition.
Group sampled (ID)
Date of sampling
Assumed time of intake
(H+h)
Sampling to counting (d)
cps per 500 mL
Average 24-h urine
production (mL d7')
for adults
Number of persons
sampled for urine in
pooled samples
Estimated excretion
fraction on day of
sampling (see text)
Average intake BY
(adult, kKBq)
87Cs deposition from
Bravo (kBq m~)
87Cs intake (kBq)
Cs intake per unit
Cs deposited (kBq
per kBg m™’)
Uncertainty of '°’Cs
deposition (GSD)
Weighted average '*’Cs
intake per unit '°’Cs
deposited*
Marshallese adults on
Rongelap Island
(LA316R)
3/16/1954
Marshallese adults on
Rongelap Island
(LA317R)
3/17/1954
8.4
Marshallese adults on
Sifo, Ailinginae
(LA319S)
3/19/1954
8.4
American military weather
observers on Rongerik
(LA319A)
3/19/1954
5.6
11.2
14
70
427
13
76
448
11
33
385
11
20
1,072
35
31
15
9
1.73 x 10
1.63 x 10“
1.42 x 107"
1.85 x 10~*
3,310
3,680
1,320
1,710
100
100
32
67
2.9
0.029
3.2
0.032
1.5
0.031 (Rongelap and Ailinginae)
1.2
0.036
1.4
0.021
1.8
2.0
0.021 (Rongerik)
* Logarithms of '*’Cs intake per unit '°’Cs deposition inversely weighted by variance of '*’Cs deposition (see text).
'’Cs per unit of '°’Cs deposited. We calculated the intake
of '°’Cs per unit deposition of '’Cs separately for the
and LA317R, Table 7) and Ailinginae (LA319S) and
0.031 Bq per Bq m* (Table 7). This indicates that the
fallout ingested by adults was approximately equal to the
material deposited on 310 cm’. Our evaluation of the
likely exposure conditions agrees with those of Lessard
et al. (1985) and suggests that particulate contamination
of Bravo '°’Cs deposited at the two atolls. For the three
of foods, utensils, hands and face, and to a lesser degree,
drinking water, led to the internal contamination of
pooled samples of adult urine collected from populations
exposed to Bravo fallout on Rongelap (groups LA316R
weighted each by the relative precision of our estimates
urine samplings (LA316R, LA317R, LA319S), our esti-
mates of '*’Cs intake per unit deposition of '*’Cs were
0.029, 0.032, and 0.036 Bq per Bq m~ while the
estimated uncertainties of the '*’Cs deposition at Rongelap
and Ailinginae, expressed as geometric standard deviations (GSDs), were 1.5 and 1.8, respectively. Our best
estimate of the '*’Cs intake per unit '°’Cs deposition was
derived from a weighted average" in consideration of the
uncertainties of the '°’Cs deposition, and was found to be
* The logarithms of the point estimates of °’Cs intake per unit
87Cs deposition had associated multiplicative uncertainties (similar in
form to geometric standard deviations). These estimates were used in
a conventional inverse variance weighting method (see Bevington
1969) as follows:
h= S\(x/0?)/ > (/e2),
adults.
As expected, our average estimate of intake per unit
deposition for American military weather observers stationed on Rongerik was less than the average for the
Marshallese since their lifestyle was less dependent on
outdoor food preparation. Our estimate of intake for the
military weather observers stationed on Rongerik was 0.021
Bq per Bq m°(also based onbioassay) or about two-thirds
of the intake per unit deposition experienced by the Marshallese on Rongelap. We interpret the estimated smaller
intake per unit deposition of the Americans to be consistent
with our belief that the military personnel took, at least,
some precautions against ingestion of fallout particles.
According to the records of Sharp and Chapman (1957),
some of the military personnel worked indoors during the
day though others continued to work outdoors. Hence, the