744
HARDY, RIVERA, AND CONARD
average urinary to fecal excretion ratio was 3.5 for ‘*'Cs and 0.06 for
Sr, These findings are in agreement with other studies during which
Sr and "Cg were ingested under a variety of experimental and accidental conditions.
INTRODUCTION
Natives of Rongelap in the Marshall Islands consume indigenous
plant and sea foods that contain long-lived fission-product radionuclides
from fallout that occurred in 1954 during Operation Castle. The body
burdens of these people, particularly with regard to Sr and "Cs, are
higher than those of U. S. inhabitants. Although estimates of total-body
concentrations of these two radionuclides have been made directly for
137Cs with a portable whole-body counter and indirectly for “Sr from
urine analyses, the amount of foods consumed varies at different times
of the year, and therefore information on the assimilation and excre-
tion of specific nuclides as related to body burden has beendifficult to
evaluate. It was felt that a controlled intake and excretion study with
the use of the “Sr and '"Cs naturally present in Rongelap food would
provide valuable data. Since controlled intake and excretion studies on
Rongelap natives was not feasible in the field, it was decided by oneof
the authors (Robert A. Conard) that useful information in this regard
might be obtained from an intake and excretion study carried out on
himself using Rongelap foods brought back to Brookhaven National
Laboratory
(BNL), where a whole-body counting facility would be
available for the study, and consumed under controlled conditions.
Although these foods did not represent a typical native diet, it was felt
that the relatively high levels of Sr and '*’Cs present in them would
make it possible to study quantitatively the excretion rates of these
nuclides after an acute ingestion.
BACKGROUND
As part of the annual medical examinations of Rongelap natives
who have been exposed to falleut radiation following the detonation of
a high-yield thermonuclear device at Bikini Atoll in March 1954,
24-hr urine specimens are collected. These samples have been
analyzed for *Sr at the Health and Safety Laboratory (HASL) during
the past several years.
The purpose of these analyses has been to
attempt to relate excretion to total-body burden of Sr resulting from
the long-term chronic exposure of the natives to this radionuclide
through ingestion. A portable whole-body counter was used during the
1961 survey, as in previous surveys, to measure the '*’Cs body burdens
of the natives directly, but this instrument has not been available for