428
if the sotuble portion of the field-ingested
+Predictions for July 10, 1974 are valid only
to that of the effe ctive dose administered during
lar
simi
manner
d
a
in
]
olized
metab
is
plutonium-238
. 1974 and 1975). See discussion in text.
aZ
et
y
(Stanle
study
metabolism
238
the plutonium-
through
(Collection period:
nineteen day multiple dose, 7 days post treatment}.
1,08 x 10-9
1.73 x 1073
3.24 x 10+
1.85
Jan, 19, 1975
**Based on plutonium-238 dioxide metabolism data of Stanley et az, (1974),
0.52 x 1075
0.83 x 10-3
1.56 x 10-4
3.85
Aug. 8, 1974
(Nineteen day multiple dose,
5.26 x 10-*+
8.42 x 1074+
1.58 x 1072+
0.038
July 30, 1974
*Based on plutonium-238 dioxide metabolism data of Stanley et ai. (1975},
73 days post treatment).
0.26 x 1075
Liver*
Bone*
Mil k**
{% of Dose)
(% of Dose)
(% of Dose)
0.43 x 1073
Since the field and soluble forms of plutonium ingested during the May 17, 1974,
and July 10, 1974, trials are unknown at present, it is not certain whether
metabolism trial results of plutonium-238 dioxide are applicable in these
0.79 x 10-4
employed in the in vitro and metabolism studies,
7.95
As previously mentioned, during the May 17, 1974, and July 10, 1974, trials
plutonium solubilities reached 902% and above, which is a marked departure
from that of other Field-ingested plutonium trials.
In addition, Barth and
Mullen (1974) reported average simulated duodenal fluid solubilities of 31.4%
23.6%, and 3.7% for plutonium-238 nitrate, plutonium-238 citrate, and plutonium238 dioxide, respectively.
This suggests the possibility that the chemical
nature of most of the plutonium ingested during these two fleld-ingested
plutonium trials was dissimilar to that of the purified plutonium-238 forms
Nov. 6, 1973
(Stanley et al., 1974 and 1975) on which the prediction is based.
In Vitro Solubility
In order to predict the metabolic behavior of the field-ingested plutonium,
the soluble fraction must be absorbed, retained, and secreted in a manner
similar to the effective dose administered during the metabolism study
Ratio
Examples are shown in Table 4 of the applications of in vitre data in conjunction with métabolism study data to predict the tissue retention and
milk secretion of field-deposited plutonium.
Ratios of plutonium solubility
in the simulated duodenal fluid of plutonium-238 dioxide to fieldingested plutonium-238 were calculated for each rumen contents collection
(Nov. 6, 1973:
3.72/0.49% = 7.55). The predicted tissue retention or milk
secretion was calculated by dividing the actual tissue retention or milk
secretion of plutonium-238 from plutonium-238 dioxide, as determined in the
metabolism study of Stanley et al. (1974 and 1975), by the in vitro solubility
ratio (liver:
6 x 107*2/7.55 = 0.79 x 107*%; milk:
2x 10752/7.55 = 0.26
x 10°°%).
Date
During this study, the outer enclosure was more intensely grazed than the
inner enclosure.
This allowed for greater regrowth of the edible vegetation
in the inner enclosure, while in the outer enclosure it was continually eaten
back.
It appeared by visual observation that there were fewer of the fruiting
involucres on the Eurotia lanata in the outer enclosure.
This suggests a
reduced plant surface entrapment of resuspended particulate material, thereby
increasing the proportion of plutonium-238 -239, and americium-241 presumably
internally incorporated into plant tissue. Under these experimental conditions
the effects of distance from ground zero and grazing intensity cannot be
differentiated.
Collection
Factors which were present in the outer enclosure,
FXAMPLES OF PREDICTED BOVINE TISSUE RETENTION AND MILK SECRETION OF FIELD-INGESTED PLUTONIUM-238
in the outer enclosure,
and which may have contributed to the marked increase in plutonium-238, -239
and americium-241 solubility, were the greater distance of the grazing area
from ground zero and a higher grazing intensity.
Romney et al. (1975)
stated that, as a general rule, the mean fallout particle size decreases
with increasing distance downwind from the point of detonation.
Hence, a
reduced mean particle size is expected in the outer enclosure which would,
in turn, result in an increase in plutonium and americium dissolution.
TABLE 4.
During the July 10, 1974, and January 29, 1975, trials, the rumen contents
were collected at the time of slaughter from nonfistulated cattle grazing