August of 1934 This method of estimauny “Zn dau acuivit. ingestion rates yields a j&-times greater estimute of tots. intake than the total Intake Ssuggesies pV bouy-burden extrapolation techmigues scuuahons «7)). Although the Zn Told; take estimate incicated for Link adults in Tabie 4 was basec on seanty datu. i was made with fewer assumptions than was the above estimate using Japanese fishing data. The vaidity of the ~’Pu data used to estimate the body burden at Rongelap Atoll (see Table 1} in 1973 had been considered by an Energs Research and Deveiopment Agencyad hoc commitiee. The committee concluded that because of the possibility of urine-sample contamination these data were uncertain. This may indeed have been a facter since a radiochemical analvsis of BRAVO ceoris indicated Rongelap Atoll was contaminated with “Pu (Ts55). No special pre- cauuons had been taken when the urine sampies were collected in the held. therefore not much credence could be given to these data. In 19%6. three male adults at Rongelap Atoll provided urine samples for -“Pu analysis. Twe vielded results below the minimum detection limit of 3.7 x 107* Bq l.~' (0 fCii.~') and one yielded 3.3 » 10°* Bqt.” (90 fCi1.~'). The aver- at this time. Several investigations are underway. In August 1981]. fecal and urine samples were obtained from Rongelap and Utunk residents and ure to be anatyzed after complete dissoluuion followed os a liquid solvent extraction techmique usec in conjuncuion with a photon-eleciron reiecting liquid scintillation spectrometer developed by McDowell] for lowlevel alpha spectroscopy (Mc72). The question ofiniual sample contamination will be answerec fe Jowing additions. analvsis of urine collected in 1980 from former Bikim: Atoll residents. the committed effective dose equivalent; the overall body-burden pattern was one of initial increase followed bv continuous decline over a period of vears: the daily intake pattern was probablyone of continuousdecline, this conclu- sion was based on the fitting of sequential bods-burden data to equation (2): the impact of each nuchde on internal committed effective dose equivalent was dependent upon the time between contaminauon and rehabitation: and the internal committed effective dose equivalent exceeded external dose equivalent during the rehabitation period. The sparse *’Pu data indi- cated further research was necessaryto estimate accurately the activity intake and committed committed effective dose equivalent since they may have been the result of an erroneous urine because the population reinhabited within months of the BRAVO event. The impact of nuclides with a long mean residence time in the diet (Cs, Sr, Fe) was greater at Rongelap nal deposition. The potential for contamination also existed for *Sr, however the impact of contamination on dose assessment was much greater for Pu. Questions concerning the ”*°Pu estimates have led to a study of the sampling and analysis procedures which indicated that some ~*Pu in urine may not have been chemically recovered along with the tracer (Ry82). The extent of sample contamination during collection and the fundamental reasons for variation in recovery of *°Pu from urine samples remain unanswered tor. The principle results of this investigation were that: '’Cs and “Zn were major contributors to effective dose equivalent from this nuclide. For committed effective dose equivalent, the collection technique and not the result of inter- doc. CONCLUSION age of these values along with the 1973 adult average data that was reported by Conard (Co75) were used to derive potential body burdens. The results were listed in Table 1. The estimates for “*Pu adult body burden were not used to derive values of intake and ergs Wit 7 x 10 Ba d~ lew been impact of nuclides with a short mean residence time in the diet (°°Zn, Co) wasgreater at Utirik because of greater initial contamination. Acknowledgments—The authors fully appreciate the fine efforts of Michael Ryan of Oak Ridge National Laboratory; Nathanial A. Greenhouse of Lawrence Berkeley Laboratory; Lee V. Kaplan formerly from Yale University; Humbilena Manalastas from the Philippine Atomic Energy Commission; William Ad- am$, Jan Naidu, John Baum, Victor Bond, Donald Borg, Eugene Cronkite, Andrew Hull and Charles Meinhold from Brookhaven National Laboratory; and Thomas McCraw from the Department of En- tomo 7) ohave cy sy! mieht (Dx TO ouCic’ i in’ Max and June and 7x TP Buec® «2 « 1 uC:d>-) in July and os rate PROTRACTED EXPOSLRE TO FALLOUT aoe S3e