\Le72, Sm72).
The data presented here provide long term biological removal rate
constants for 13765 and 60c5 determined from the Marshallese population exposed to these nuclides primarily through dietary pathways.
When the Bikini population was relocated, their new residence islands were
essentially free of radioactive contamination due to the United States weapons
testing program.
Persons having lived exclusively in contamination free environ-
ments were used as controls.
Their 137 Cs and 606, body burdens during the May
Survey were assumed to be representative of the baseline body burden status of
the Bikini population prior to their return to Bikini.
The equation used to
calculate the long term biological removal rate constants for both radionuclides
is of the form
(anc) = (Bec)e 7 (H*4t
(1)
where
A = measured body burden in May, 1979, Bq
3 = measured body burden in January, 1979, Bq
al
~
C = averaged measured body burden of the control population in May, 1979
instantaneous fraction of radioactive atoms removed per unit time dy
biological mechanisms, al
A = instantaneous fraction of atoms removed per unit time by radioactive
decay, ai
t = elapsed time between measurements, d.
Values of the radiological decay rate constant for each nuclide were obtained from the Atomic Data and Nuclear Data Tables (AD76) and are 6.3 x lo?
at for 1376,
and 3.6 x 10 * a for 6000.
The baseline mean 13765 body burden is 60 Bq as determined from 47
measurements with results ranging from the system detection limit (37 Bq) to
5