Table 5. Estimates of the daily intake of 37Cs
Adult (2 18 y). The average daily intake of
from local foods by age group at Rongelap Atoll.
137Cs for adults is obtained from our diet model.
When imported foods are available, the intake
Age
is 1085 pCi/d (specific data are presented in
Appendix A, Table A-1).
A summary of the !97Cs intake by age group
is given in Table 5.
137Cs intake, pCi/d
Q to 3 months
4 to 8 months
9 monthsto 1.4 y
l5yto3y
424
556
773
517
4ytolly
594
12y toi7y
218y
761
1085
Retention of 137Cs and 99Sr
represented by a two-compartment, exponential
model, where for adults the short-term
Cesium-137
_ compartment has a biological half-life (T'/?) for
Fetus
137Cs of 2d for both males and females, and the
long-term compartment a T!/? of 110d and 85d
The fetus is assumed to be in dynamic
equilibrium with the mother. Experimental
results indicate that in the first few monthsof
pregnancy theratio of the 137Cs concentration in
mothers to that in the fetus is 3:1, changing to
about 1:1 in last months (linumaet al., 1969;
Nagai, 1970). Consequently, the dose received
by the fetus should be no more and perhapsless
for males and females, respectively (ICRP, 1979;
NCRP, 1977; Richmondet al., 1962). In some
cases, the loss of 137Cs is better represented by a
three-compartment model (Leggett et al., 1984),
but generally the short-term compartmentin the
two-compartment model represents an average
of compartments with half-lives the order of a
few hours, a few days, and 1 or 2 weeks. The
than that received by the adult mother (Jinuma
fractional deposition of 137Cs in the model for
et al., 1969; Nagai, 1970).
In addition, the biological half-life of
137Cs
the short- and long-term compartments for
adults is 0.10 and 0.90, respectively (ICRP, 1979;
NCRP, 1977). These fractional depositions and
is shorter in pregnant women than in
nonpregnant women, leading to lesser body
burdens in pregnant women (Bengtsson etal.,
half-lives represent a model for an average
adult around which particular individuals will
vary.
The long-term compartment is the most
1964; Zundelet al., 1969; Godfrey and Vennart,
1968). Consequently, the dose to pregnant women
would be less than to nonpregnant women. Based
on data presented by linuma etal. (1969), the
significant compartment for dose assessment, and
there is abundant evidence in the literature that
dose to the fetus would be about half that
calculated for an adult.
showsthe long-term T!/? changes dramatically
with age from birth to adulthood (Lloydetal.,,
Infants, Children, Adolescents, and Adults
1966, 1970; Wilson and Spiers, 1967; Boni, 1969;
"It ig assumed that when 137Csis ingested,
linuma etal., 1969; Weng and Beckner, 1973;
100% of the 137Cs crosses the gut and enters the
Lloyd, 1973; Cryer, 1972; Karcher et al., 1969;
Richmondetal., 1962). The T'/? for 137Cs_ ranges
blood, i.e., Fy = 1.0 (NCRP, 1977; ICRP, 1979).
The loss of 137Cs from the bodyis then generally »
a
Crt
JuuE ZOO
from 10 to 12 d in infants (Wilson and Spiers,
12