qa
(7) Activity incorporated in skeleton during 20 daysof intakeis diluted in total skeletal
mass at least 100 times greater than 20 day incremental mass (PE—factor of 2). (In
rapidly growing adolescent this dilution takes place at time of ingestion. In infant,
dilution takes place with subsequent growth before a large fraction of the activity decays.)
Few localized “hot spots” exceed average skeletal dose rate by factor greater than 10.
The infinity dose resulting under these assumed conditions from a fallout of 1 KT/mi? is
shown in Table 5.
b. Sr-89 (calculations for infant):
Assume:
(1)
in milk.
(Sr-89/Ca) food
(Sr-89/Ca) vegetation
=0.2 (PE=factor of 2) as a result of selection against Sr
When infant on mother’s milk, double selection would occur.
For older child
on solid diet, selection against Sr would be by smaller factor, but dilution in (3) would
be greater.
(2) Assumptions (2)-(6) for Sr-90.
(3) Activity incorporated in infant’s skeleton during 20 days’ intake is diluted in total
skeletal mass at least 10 times greater than 20 days incremental mass (PE=factor of 1.5).
The infinity dose computed, under these conditions, for a fallout of 1 KT/mi? is shown in
Table 5.
c. Ba-140 (calculations for infant):
Assume sameasfor Sr-89, except that:
(Ba/Ca) food
==0.05 (PE—factor of 3).
(Ba/Ca) vegetation
and
(Ba/Ca) skeleton
=0.25 (PE=—factor of 2).
(Ba/Ca) food
These assumptions lead to the infinity dose as shown in Table 5.
d. I-131
(calculations for infant):
Assume:
(1) 35 lbs/day cow feed intake, dry weight basis (PE—factorof 1.2).
(2) 10% of cow I-131 intake transmitted to milk (PE—factor of 2).
(3) Infant drinks 5% of milk production of 1 cow (PE—factorof 1.5).
(4) Infant thyroid mass=1.5 gm (PE—factorof 2).
(5) Infant thyroid retention=-30% of ingested I-131 (PE—factor of 2).
These assumptions lead to the infinity doses as shown in Table 5.
4. Fission product ingestion in drinking water:
Fission products will also be ingested in the drinking water. The following general assumptions are made for all isotopes:
(1) An individual, per 70 kg of body weight, consumes an amount of water equal to
the rainfall on 13 ft? (PE—factor of 2). (Two liters/day drunk, 25 inches/yr rainfall.)
(2) 2% of activity remains in solution in water, the remainder being filtered out or
absorbed in watershed soil, etc. (PE—factor of 4).
(3) Delay between fallout and consumption gives exponential function for intake
vs. time, half of total intake occurring in 40 days (PE=-factorof 3).
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DO® ARCHIVES