C:
q
pertinent to estimate body burden, burden expected at equilibrium, and daily
intake of Sr?° from these excretion levels.
The metabolic behavior of strontium as outlined in Supplement #6 of the
British Journal of Radiology was used to estimate body burden, etc. from urinary
excretion levels of strontium? (Appendix).
The fraction of strontium absorbed
from the gastro-intestinal tract is 0.6 and the biological excretion rate from
the total body is 190 days.
Of the absorbed fraction, 0.25/0.60, about 42 per-
cent is deposited in bone and the biological half-life is 4000 days.
Assuming
that the absorbed fraction is excreted entirely in urine, the mean body burden
of the exposed Rongelap group in March 1958 was 2 muc (+ 52 percent).
“about nine percent of the expected equilibrium value of 23 mc.
This is
The estimated
burden of strontium? for March 1958 is probably too low and compares with
levels measured in stillborn children in the U. S. several years ago (8).
The
daily intake of strontium? is estimated to be about 15 micromicrocuries or 15
Sunshine Units (assuming a daily calcium intake of one gram).
Dunning (2) reported that the average concentration of strontium?° in the
Marshallese food supply could be about 360 Sunshine Units, but this would reduce
to well under 100 Sunshine Units if the consumption of high Sr’° content foods
were eliminated.
With the elimination of pandanus and land crabs the diet used
by Dunning indicated that the intake of strontium”© would be 17 Sunshine Units
“per day.
This compares favorably with the estimated inteke of about 15 micro-
microcuries from excretion analysis.
Zine©> Excretion Levels and Body Burden
In early 1957 Miller (9) detected Zn©> in selected residents of Rongelapand Utirik by whole body gamma-ray spectrometry.
Body burden ranged from 29.5
to 73.0 muc for the Rongelap residents, and 482 and 229 mic was detected in two
The Rongelap subjects were residing on Majuro at this time.
NI
subjects from Utirik.