Urine No, Dry-ashed Date Personnel Location c/m/100 m) 3/16 Natives Rongelap 204, 6/17 3/17 Natives Rongelap 186 6/18 3/19 Natives Rongelap 85 6/22 AM U.S.A.F. 53 6/23 No. 40 Natives Rongerik 3/28 Jap. fish. FortinttON. ee 4/14 Jap. fish. 4/19 Jap. fish. 47 Classification chan od te Counted Ancle SA fh 6/8 ( ~Kibjo é at OG Dragont crocs aeihoriZingchange ip7classificats om By "Gea Fehr OV, 28 4 "re of person maxing ‘the chang3 Cand date) (Sig Thus, 1t may be concluded that the exposure of the Japanese fishermen to internal radiation hazard was about the same as the U. S. Air Force personnef and perhaps one fifth as much as the groups of natives on Rongelap. However, this comparison is rendered somewhat uncertain by the fact that the urine samples were collected one month later from the Japanese than from the natives. Determinations were also made for l1 lation methods. 131 ,» or 89 “°, Ru, Pu, and Ce by iso- No cerium or Pu activities were found. 1131 was isolated from urine samples and identified by the decay rates, The specificity of the extraction methods together with the decay rate determinations leaves no doubt of the presence of considerable amounts of 331 activity in these urines. However, no method of extraction of I from urine quantitatively is known, so total content values are probably more accurately obtained from whole dried urine sample counting rates. Yield on extraction is thought to be about 60% and order of magnitude results may be obtained by assuming this yield. or 89 was obtained with observed counting rates up to 1000 c/m/sample and decay rates were checked by observations during many weeks. However, chemi- cal yields were somewhat uncertain because of difficulties in the methods at the poe /0