1967; Lloyd, 1966), to 20 to 50 d for children
(Karcher et al., 1969; Boni, 1969; Naversten,
1964; Bengtsson et al., 1964; Lloyd et al., 1966,
1970), and to 110 d and 85 d for adult men and
with body weight and age is only significant
when infants, juveniles, and teenagers are
included and that there is no correlation with
either for adult males or adult females
women (Richmond et a]., 1962; Van Dilla, 1965;
Boni, 1969; Lloyd, 1966; Lloyd etal., 1970; ICRP,
(Karcher, 1973; Cryer, 1972).
The only
newborns, decreases to about 13 d by 1 y, and then
begins to increase again to about 30 d by 5 y.
(Lloyd, 1973; NCRP, 1977; ICRP, 1979). The
average biological half-life for 137Cs in
significant difference in T'/? among adultsis
1979; NCRP, 1977). Leggett (Leggett, 1987)
indicates that the long-term T'/?is about 22 d for
that between males and females where there is
a distinct difference in the average body weight
In addition to the change in T'/? with age,
Japanese males, whose average body weightis
the fractional deposition of 197Cs_ in the short-
significantly less than for U.S. and European
and long-term compartments also changes
(Leggett et al., 1984). The fractional deposition
for newborns is 0.5 in the short-term
compartment and 0.5 in the long-term
males, was determined to be about 85 d
respectively, for adults.
that the strongest correlation for the biological
compartment; this gradually changesto 0.10 and
0.90 for the short- and long-term compartments,
Table 6, abstracted
from Leggett (1987), shows the change with age
for the total body potassium, fractional
deposits, and T1/2.
Models have been proposed indicating that
the long-term T!/? for 137Cs is correlated with
age (Boni, 1969; McCraw, 1965; Weng and
Beckner, 1973; Fisher and Snyder, 1967), body
weight (Eberhardt, 1967; Cryer, 1972), and sex
(Clemente et al., 1971; Boni, 1969).
However,
(Uchiyama et al., 1969; Fujita, 1966).
Lloyd
indicates that it is more likely that the T'/? for
137Cs is correlated with some other factor
commonto age, body weight, and sex.
Leggett (1986, 1987) has recently shown
half-life of 137Cs appears to be with the total -
amountof potassium (K) in the body. The model
proposed by Leggett is the standard twocompartment modelof the form:
A(th=a e0.693 t/T14 (1-a)e0-693 t/T2 ,
where
A(t)
= the 137Cs activity in the body at
Lloyd (1973) has indicated that the correlation
time t after ingestion,
PETAes
er en
ea
te tS AL. bee 50 RE ERT Arm rn
Table 6. Estimated compartmental fractions and half-times in the age-dependentretention function
for cesium.
Age
Total-body K
Short- plus
Short- plus
intermediate-
term fraction
(days)
intermediate-
term T1/2
Long-term
fraction
Long-term T?/?
(days)
Newborn
100 days
5.2
11.4
0.60
0.60
22
16
0.40
0.40
22
16
1 year
5 years
20.8
42.7
0.60
0.45
13
9.1
0.40
0.55
13
30
0.13
2.2
0.87
93
10 years
15 years
Adult
71.0
1314
20GRZ5
150
0.30
°°
0.10
5.8
1.6
0.70
0.90
50
107