body burden means for adults on Utirik and the observed Kp, rate constant from
Rongelap.
It was observed on Rongelap that .031% of 65 “Zn was removed from the
diet pathway each day in addition to radioactive decay.
Additionally, reduction
in dietary radioactivity on Rongelap had been observed for 1376, 9065, and 6004
to be greater than that predicted by radioactive decay alone.
Instantaneous re-
duction fractions very similar to those at Rongelap were observed at Utirik for
the 90c., and 1376, nuclides.
The lower curve on Figure 16 reflects the dose
equivalent, dose equivalent rate, and body burden which would have occurred had
.
.
radioactive decay alone accounted for the removal of
ronment.
65
a
.
“zn from the Utirik envi-
Since additional mechanisms couldebe measured for other nuclides at
}
Utirik and for the 65 Zn nuclide on a nearby atoll, the upper curve was chosen as
the most likely body burden history for adults post return to Utirik Atoll.
Figure 17 indicates the Utirik adult mean total body dose equivalent rate
for each nuclide.
An obvious difference relative to the Rongelap history
exists; 6520 not 13764 was the major nuclide contributing to the dose equivalent
rate,
This was due to the Utirik population returning 3 to 4 months after the
initial contaminating event, and the Rongelap population returning after 3
years.
The age of the fallout had a dramatic influence on the importance of
each nuclide contributing to the internal dose equivalent.
In fact 600, and
6525 played major roles during the first 3 years, a time interval that
corresponded to the period during which field whole body counting facilities
were being developed at Brookhaven National Laboratory and when medical examinations for people on Utirik Atoll were not done.
Additionally, pooled and/or in-
dividual radiochemical analysis of urine was not performed during this period.
The impact of 6525 and 600, was such that even if the least conservative rate
34