so

te
*

body burden méans for edults:on Utirik and the observed K, rate ‘constant from
Rongelap.

|

It was observed on Rongelap that .031% of

65 “Zn

diet pathway each day in addition to radioactive decay.

was removed from tle

Additionally, reduciion

pee

- 137

in dietary radioactivity on Rongelap had been observed for

~ Cs,

to be greater than that predicted by radioactive decay alone.

90

Sr, and 8005

Instantaneous re-

duction fractions very.slabipe&6) phbde! gtBonga apvere joobserved at Utirik for

the sr, and 137 c4 nuclides.

The lower curve pn‘Pigure/16: reflects the dose

equivalent, dose equivalent rate, and body burden which yould have occurred liad

radioactive decay alone accounted: forithe removal of a from the Utirik envi i

ronment.

Since additional!mechanisus could be measured for other nuclides at
AAV \MI y
poe

Utirik and for the 6575 nuclideon a nearby ato}l,* the upper,curve was chosen as

the most likely body burden history for adults post return

Utirik Atoll.

Figure 17 indicates the Ucirik adult mean total body gue equivalent rate
for each nuclide.

An obvious difference relative to the Rongelap history

exists; 6575 not 1370, 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 face 600, and

655, played major roles during the first 3 years, a time interval that
QB

were being developed at Brookhaven National Laboratory and when medical exaiina-

td

tions for people on Uririk Atoll were not done.

Additionally, pooled and/ur in-

eat

corresponded to the period during which field whole body counting facilities

dividual radiochemical analysis of urine was not performed during this periad.
.

The impact of

65

.

.

?2n and 6005 was such that even if the least conservative rate

14

CORE LL A ater ee eg eee

.

the

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