746
HARDY, RIVERA, AND CONARD
consumption of the Rongelap food, for three- and four-day periods while
the food was being consumed, and for two consecutive three-day periods
after the last day on which the Rongelap food was consumed. Thereafter, for the next 184 days, 24-hr excreta samples were collected on
Friday of each week. Whole-body counts were done at regular intervals.
Food aliquots and excreta specimens were sent to HASL for "Sr
and '’cs analyses. The food was dry-ashed in a muffle furnace at
approximately 450°C and solubilized by fusing with sodium carbonate
and dissolving the pulverized melt in hot water and finally mineral
acid. Cesium-137 was separated by the hot-water leach and then
extracted from solution with ammonium phosphomolybdate. The cesium
was purified by sorption on the selective elution from a cationexchange resin and then precipitated as the tetraphenylborate for
counting. A complete description of this procedure is given in the
HASL procedural manual.’ The mineral-acid portion of the dissolved
melt was evaporated to dryness in dilute acid. The dehydrated silica
was filtered, and a carbonate-collection precipitation was carried out
on the solution. After filtration the carbonate precipitate was dissolved
in nitric acid, and the solution was evaporated to dryness. Successive
fuming nitric acid separations were used to separate strontium from
calcium and other interfering ions, Radium and lead were removed by
scavenging with barium precipitated as the chromate. Traces of other
fission products were scavenged with yttrium hydroxide. After equili-
bration of the “Sr with its daughter, ““Y was precipitated as the
hydroxide and converted to the oxalate for counting. This procedure is
also described in the HASL manual.® All counting was done with lowlevel beta scintillation counters designed at HASL.® The urinary and
the fecal samples were wet-ashed with nitric acid, and the residues
were fused to effect complete dissolution. From this point, identical
procedures to those previously described were used to separate
Sr and "Cs,
Cesium-137 body burdens were measured with the BNL whole-
body counter. Measurements were taken at convenient intervals during
and after the consumption of the Rongelap food. These '*’Cs values were
corrected for contributions of '*’Cs present in the normal diet. This
correction was made with the assumption that the subject’s normal
diet during the experimental period was similar to that of non—milkdrinking BNL personnel during the same period. The normal body
burden was assumed to have increased linearly!’ from 6.35 nc in July
to 10.8 nc at the end of December 1963.
RESULTS
The amount of "Sr and '"cs ingested via the Rongelap food over
the seven-day period is shown in Table 1. Pandanus contributed the