1334 vf + FALLOUT ‘FROM NUCLEAR WEAPONS TESTS pertinent to estimate body burden, burden expected at equilibrium, and daily intake of sr? fron 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, ete. from urinary excretion levels of strontiws?° (Appendix). The fraction of strontium absorbed from the gastro-intestinal tract is 0.6 and the biological excretion rate from the total body 1a 190 dsys. 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 mac (+ S2 percent). about nine percent of the expected equilibrium value of 23 mic. This is The estimated burden of strontium’? for March 1958 is probably too low and compares vith levels measured in stillborn children in the U. S. several years ago (8). The daily intake of strontium” ia estimated to be about 15 micromicrocuries or 15 Sunshine Unite (aseuming 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 vould reduce to well under 100 Sunshine Unite if the consumption of high Sr’? content foods were eliminated, With the elimination of pandanus and land crabs the diet used by Dunoing indicated that the intake of strontium’ would be 17 Sunshine Units per day. This compares favorably with the estimated intake of about 15 micro- Microcuries from excretion analysis. Zinc©S Excretion Levele and Body Burden In early 1957 Miller (9) detected zn°> in selected residents of Ronge lap and Utirik by whole body gamma-ray spectrometry. Body burden ranged from 29.5 to 73.0 me for the Rongelap residents, and 482 and 229 muc was detected in two subjects from Utirik. The Rongelap subjects were residing on Majuro at this time.