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Health Phisies Voi 46. Ne 3 (March), pp S11 527) 1984
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1984 Health Physics Socer.
Pergamon Press Lic
PROTRACTED EXPOSURE TO FALLOUT: THE
RONGELAP AND UTIRIK EXPERIENCE?
E. T. LESSARD., R. P. MILTENBERGER. S. H. COHN, 8. V. MUSOLINO and R. 4. CONARD
Brookhaven Nauonal Laboratory, Upton. NY 1197:
(Received 9 July !982: accepted 9 Mav 1983)
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Abstract--From June 1946 to August 195s. the U.S. Department of Defense and the US.
Atomic Energy Commission (AEC) conducted nuclear weaponstests in the Northern Marshall
Islands. On 1 March 1954, BRAVO. an above-groundtest in the Castle series. produced high
levels of radioactive material, some of which subsequently fell on Rongelap and Utrk Atolls
due to an unexpected wind shift. On 3 March 1954, the inhabitants of these atolls were moved
out of the affected area. Theylater returned to Utink in June 1954 and to Rongelap in June
1957. Comprehensive environmental! anc personnel radiological monitoring programs were
initiated in the mid 1950s by Brookhaven National Laboratory to ensure that >ody burdens
of the exposed Marshallese subjects remained within AEC guidelines. Their dody-burden
histories and calculated activity ingestion rate patterns post-return are presented along with
estimates of internal committed effective dose equivalents. External exposure data are also
included. In addiuon. relationships between body burden or urine-activity concentration and
declining continuous intake were developed. The implications of these studiesare:
{1} the dietary intake of "Cs was a major component contributing to the committed
effective dose equivalent for the years after the initial contamination of the atolls;
(2) for persons whose diet included fish, “Zn was a major component of committed effective
dose equivalent during the first years post-return:
(3) a decline in the daily activity ingestion rate greater than that result:ng from radioactive
decay of the source was estimated for '"Cs.“Zn. Sr and “Co:
(4) the relative impact of each nuclide on the estimate of committed effective dose
equivalent was dependent upon the time interval between initial contamination and rehabililation: and
(5) the interna] committed effective dose equivalent exceeded the external dose equivalent
by a factor of 1.) at Uurik and 1.5 at Rongelap during the rehabitation period.
Fewreliable “*Pu measurements on human excreta were made. An analysis of the tentative
data leads to the conclusion that a reliable estimate of committed effective dose equivalent
requires further research.
INTRODUCTION
of six nuclear-weapons tests in the Castle series,
was detonated. Due to an unanticipated wind
shift, the BRAVO device produced substantial
surface contamination on inhabited atolls up to
Wee a
SUBSEQUENT to World WarII, the United States
carried out several series of atmospherictests of
nuclear weapons in the Northern Marshall Islands between the years 1946 and 1958. On |
500 km east of Bikini within a 5000 km? area.
March 1954 at Bikini Atoll, BRAVO,the first
:
The contaminated region was cucumber-shaped
and falling bomb debris was visible on Ron-
gelap Atoll from 5 to 10hr after detonation
+Research carried out under the auspices of the
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U.S. Department of Energy, Contract No. DE-
(GI62; Sh57).
Following a fallout alert by a Navy mon-
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