SLIDE 55
Status of plutonium measurements. The validity of the 239py data used to
estimate the body burden at Rongelap Atoll in 1973 had been considered by an
Energy Research and Development Agency ad hoc committee.
The committee
concluded that because of the possibility of urine-sample contamination these
data were uncertain.
This indeed may have been a factor since a radiochemical
analysis of BRAVO debris indicated Rongelap Atoll was contaminated with
Pu
(Ts55).
No special precautions had been taken when the urine samples were
collected in the field,
results.
therefore not much credence could be given to these
In 1976, three male adults at Rongelap Atoll provided urine samples for
*?%pu analysis. Two yielded results below the minimum,detection limit of 3.7
x 10°
Bq l
(10 fCi 1
) and one yielded 3.3 x 10
Bq l
(90 fCi 1 1), The average of these values along with the 1973 adult average
result that was reported by Conard (Co75) were used to derive potential body
burdens.
The estimates for 239p, adult body burden were not used to derive values
of intake and committed effective dose equivalent since they may have been the
result of an erroneous urine collection technique and not the resudf of
internal deposition.
The potential for contamination existed for
Sr,
however the impact of contamination on dose assessment was much greater for
Pu.
Questions concerning the 239py estimates have led to study of .ghe
sampling and analysis procedures which indicated to us that some
Pu in
urine may not have been chemically recovered along with the tracer (Ry82). In
August 1981, fecal and urine samples were obtained from Rongelap and Utirik
residents and are to be analyzed after complete dissolution followed by a
liquid solvent extraction technique. This method is being developed to be
used in conjunction with a photon-electron rejecting liquid scintillation
spectrometer developed by McDowell and duplicated by us for low-level alpha
spectroscopy (Mc72). The question following additional analysis of urine
collected in 1979 and 1980 from former Bikini Atoll residents. The urines
were collected in a, ggntamination free environment and indicate higher than
expected levels of
Pu.
Further analysis using fission track-etch
techniques will be done to confirm these results.
Additionally, a comparison
population has been chosen and samples collected from them.
The await
analysis.
239py MEASUREMENTS
Date
Male Adult Population
mBq d™'
239Du Excretion Rate
1974
1975
Bikini Males
Bikini Males
0.9
0.7
1976
1979
Bikini Males
Bikini Males
0.4
2
1976
Rongelap Males
1976
1973
Bikini Males
0.5
Rongelap Males, Females
53
9
2