Urinary excretion of radionuclides @ P. S. Harris ET AL. The most important urine samples from the pointof-view of dose reconstruction were those assayed at the LASLat the end of March 1954 for '*'I (see Table 1). No other samples were obtained soon enoughafter exposure to successfully measure '*'I. The value of the samples to dose reconstruction requires careful consideration in regard to their completeness and representativeness, primarily because seemingly small volumes of urine were obtained. The Marshallese health assistant, who directed the collection, assured the on-site LASL inves- tigator (P.S.H.) that complete 24-h urine samples could 221 gamma-ray emissions made on raw samples and on the volatile fraction.******5> Only the earliest samples collected by LASL and measured for ''T within 30 d of exposure have offered quantitative measurement data useful for reconstructing doses to the thyroid gland from radioiodines. Gamma activity measurements used a photomultiplier-based scintillation detector (Fig. 1) developed at LASL coupled to a 100-channel spectral analyzer. The detector system was referred to as the “scintillation arm counter” (SAC), because the operator’s be collected, and afterwards, were collected. The original interpretation of the urine data by one of us (P.S.H.**) arm could be inserted into the chamber that held up to two 500-mL bottles. While no records have been found collections. Herein, as well as in Simonetal. (2010b), we ness, we believe the scintillation fluid to have been diphenyl oxazol (PPO) plustripheny! dioxazol (POPOP) in toluene as used in the construction of a whole-body was that urine samples collected were complete 24-h support the interpretation that, on average, those are legitimate conclusions. of the dimensions, wall material, and scintillator thick- counter at Los Alamos (Anderson et al. 1956) with a Radioactivity measurements Several types of measurements and assays for different radionuclides were performed in 1954 though some of the radiometric analyses were rudimentary by today’s standards and, in some cases, the measurement techniques were non-specific or had insufficient detection sensitivity (Table 2 and Appendix). Table Al summarizes the various assays conducted on urine samples collected in 1954. Here again, this summary was developed from the collection of literature available to us. Because of the importance of the LASL '°'T measure- similar but larger design. The detector system was used for measurements of 'S'T in liquid form. Measurements of both the raw urine sample and the volatile fraction were made.*****55* Tt was found near the end of March 1954 that 77% of the gamma emissions were in the volatile component and it was identified to be '*'I through determination of the half-life.******55 However, the measurements of activity of '*'T in urine used for all subsequent intake calcula- tions** (Lessard et al. 1985; Simon et al. 2010b) were ments to dose reconstruction, we emphasize those measurements, though in Table Al, we also briefly review the methods and findings of the other various radionuclides measurements based on descriptions that can be found today in archival documents. REAR END VIEW OF SAC Array of * PM tubes LASL samples and measurements. Iodine-131 in adult urine samples following the deposition of Bravo fallout was measured at LASL.*#7>**#*588 There were primarily two types of measurements: measurements of Table 2. Bioassay measurements reported by investigation group (Y indicates that assay was conducted). Radionuclide 81Cs Sr LASL (ee Tangham 1954) USNRDL (Cronkite et al. 1956) Walter Reed (Woodward et al. 1959) Y Y — Y Y — Sr — Y — — 13 ly Y — — “Ba Y Y — 239,240Dy, Y Y __ Y Y Y — BRy Ca Gross beta-activity Pu Y — Detector shell containing liquid scintillator FRONT VIEW OF SAC etCae bottle Y — — — Fig. 1. Drawing of front and rear views of “scintillation arm counter’ (SCA) developed at LASL for gammaactivity measurements and used to assess ''I activity of pooled urine sample in 1954.