infants, children, and adults in 1974 (Robison
etal., 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 157Cs and 99Sr.
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 ina
person} is the product of several factors:
TY?
De 2iCixlix fixxd
1. The diet—the g/d intake of various
foods. —
2. The radionuclide concentrationsin the
various foods.
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 consumption of
local foods at a contaminated atoll. Thus, the
relative consumption of imported andlocal foods
where
C;
I,
=
the radionuclide concentration in
food i, pCi/g,
= the intake of food i, g/d,
Ty’ = the effective half-life of the
fj
d
radionuclide, d,
= the fractional deposition of the
radionuclide in the body or
selected organ, unitless,
= the dose equivalent
rate
conversion constant for a unit
activity in the body, rem/pCi.
The effective half-life, Te, is the combina-
tion of radioactive decay (TY?) and biological
elimination after ingestion (Ty*). This combination is Te* = (Tya TH)Te n or in terms of
elimination constants, Ap =AR 4 Ap.
: Including Te? and f; in an overall umbrelia
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:
is very important for estimating the daily
intake ofSr and 137Cs.
These four basic categories will be discussed
and the results combined to indicate the relative
dose equivalent for infants, children, and adults.
Wewill 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 any atoll; only the daily intake
. of radionuclides, and consequently the
magnitude of the dose, would vary amongatolls
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 9°Sr to help lay the foundation for
the results.