II. A. METHODS AND RESULTS !3lt Intake at Rongelap Island Based on Urine Bioassay Results Urine samples for 24-hour elimination were pooled and collected on the 17th day post-detonation from persons evacuated from Rongelap Island (Co72). The urine was sent to Harris at Los Alamos Scientific Laboratory and an estimate of thyroid-absorbed dose from internal emitters was reported by Cronkite (Cr56). The 64-person composite urine sample was 752 adult urine (18 2, >16 years of age), 20% adolescent and child urine (4.8 2, 5-16 years of age), and 4.8% child and infant urine (1.2 2, <5 ovears of age) (Ja64). ity of 0.48 kBq (1.31 x 1072 pci) of Harris indicated a mean activ- 1311 in the Rongelap adult 24-hour urine taken on the 17th day post-detonation (Co72) and an adult mean peak thyroid con- tent of 414 kBq (11.2 uCi) (Ha54). This peak estimate was calculated on the as- sumption that 0.1% of stable iodine burden on the first day would be eliminated via urine between the 15th and 17th days (Co72). Table 1 is a tabulation of the fraction of an initial 1311 activity intake by ingestion that would be eliminated by an adult on a given day post-intake. Two models were used to calculate these daily fractions, one developed by Johnson (Jo81) and the other by ICRP (ICRP79). Both models had feedback incorpo- rated into the estimate of the fraction of initial intake. Both were solved using catenary compartment kinetics and both led to similar values for elimination of I by a reference man. Values for fractions of an initial intake excreted by female individuals were higher than for males on days 10 and 25 but were the same on day 17. A comparison to an excretion function based on results for a normal adult male was made and values were tabulated for the intake of stable iodine (see Table 1). The stable fraction compares indirectly with the I fraction through adjustment for radioactive decay. On the basis of 0.48 kBq (1.31 x 1072 uCi) in adult urine on the 17th day post-intake, a 3440 kBq (93 uCi) intake was estimated for 1317, land, ingestion at 0.5-day post-detonation was assumed. at Rongelap Is- The intake of 3440 kBq (93 UCi) was used as a normalization point. That is, once we had determined the relationship between 131 and the other nuclides in fallout, we estimated the contribution to thyroid dose from all radioiodines, while keeping the 1311 intake at 3440 kBq (93 Ci). A similar method used by Cole and James to estimate thyroid absorbed dose (Co72,Ja64) differs from ours in that 1) we used the relationship between radioiodines and 131] based on BRAVO fallout measurements, 2) we based the intake time (post-detonation) on diet and living pattern observations, and 3) we determined the mode of intake to be inges~ tion. B. Radioiodine Air Concentrations Based on Meteorology 1. Calculation of Bravo Fallout Patterns. Downwind exposure-rate contours for the BRAVO detonation were estimated by several groups (Armed Forces Special Weapons Project, Rand Corporation, Naval Radiological Defense Laboratory) (Ha79). These contours, which were based on observations of BRAVO cloud dimensions and hodographs developed for 3 hours, 6 hours, and 9 hours post-detonation,