infants, children, and adults in 1974 (Robison
et al., 1975).
In this report, we discuss in more detail the
methods
for
estimating
the
relative
radiological dose to infants, children, and
adults as a result of ingestion of 197Cs_ and Sr.
We have included recent data on physiological
parameters, dosimetry models, and diet.
The total dose equivalent (D) from ingestion
of a radionuclide to a person (or an organ in a
person) is the product of several factors:
1
_
D« EG xlxftx TE? xd
0.693
where
C;
I,
Th
»
2. The radionuclide concentrations in the
variousfoods.
3. The deposition and retention of the
radionuclides in the body.
4. The dosimetry of the ingested
radionuclides.
The combination of the dietary intake and
the concentration of the radionuclides in food
items determines the intake of radionuclides.
Consequently, the radionuclide intake is
directly proportional to the g/d consumptionof
local foods at a contaminated atoll.
Thus, the
relative consumption of imported andlocal foods
= the radionuclide concentration in
food i, pCi/g,
= the intake of food i, g/d,
= the efrective
half-life of the
radionuclide, d,
f;
= the fractional deposition of the
radionuclide in the body or
d
= the dose equivalent
rate
conversion constant for a unit
activity in the body, rem/pCi.
selected organ, unitless,
The effective half-life, Te’, is the combina-
tion of radioactive decay (T'e’) and biological
elimination after ingestion (Ty ). This combination is Ty? = (TH. + T/Te
ve or in terms of
elimination constants, Ap =AR 4 Ap.
Including Te’ and f, in an overall umbrella
of “deposition and retention,” there are four
separate categories for which data must be
available in order to estimate the dose to people
from ingestion:
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1. The diet—the g/d intake of various
foods.
is very important for estimating the daily
intake of Sr and 137Cs.
These four basic categories will be discussed
and the results combined to indicate the relative ©
dose equivalent for infants, children, and adults.
We will use radionuclide concentration data in
local foods at Rongelap Island at Rongelap
Atoll as a specific example for the calculation.
Moreover, the relative doses established. by the
methodology for the different age groups would
be the same for anyatoll; only the daily intake
of radionuclides, and consequently the
magnitude of the dose, would vary among atolls
or islands within an atoll.
Because of the anticipated diverse audience
of scientists and laymen to whom this report
will
be distributed,
we
have
included
a
significant literature review on the intake and
distribution, the retention, and the dosimetry of
137Cs and 99Sr to help lay the foundation for
the results.