te: - eneree a neBee ene dusty surfaces would be secondary pathways. oo ok. Beeee During the midday meal at Rongelap Island, BRAVO dust probably fell directly onto plates and on the surfaces of The area of one plate exposed to BRAVO fallfish which were drying in the open. out plus the area of a small fish is approximately 0.04 m*. If a 30-minute lunch interval beginning at 5 hours post-detonation was assumed to be the plate and fish exposure interval to dust, then about 40 mg would fall on this eating area at Rongelap Island. During the preparation of the evening meal, about 0.1 m* of surface area was assumed as the family food preparation area exposed to dust during fallout deposition. On the average, each family was estimated to consist of about 4.5 people (Sh57). Therefore an additional 100 mg of BRAVO debris per family member was estimated to be consumed with the evening meal at 12 hours post-detonation. As-indicated by our reassessment of the urine result, a 3.4 x 106 Bq (93 uci) intake of !3!1 was estimated on the basis of measured 131ly in urine on day 17. This was assumed to be a total per adult ingestion intake of about 1.1 x 106 Bq (30 uCi) at 5.5 hours post-detonation and 2.2 x 106 Bq (60 uci) at 12 hours post-detonation. Therefore, intake with midday and evening meals provided us with a reasonable pathway in terms of the mass of fallout ingested since 140 mg corresponded to 3.3 x 106 Bq (90 uci) of 13!r, In Table 17 we have presented the estimated activity intake (with meals) of selected nuclides at Ronge lap Island. An aduit male was assumed to take in 3.4 x 10° Bq (93 uCi) of lt in order to normalize with urine data. Other nuclides were estimated by normalizing the 13ly intake to Bikini ash composition which, in turn, was normalized to exposure-rate measurements. Activity intake with meais was modified to agree with meal intakes appropriate for body weight for the different age members of the exposed populations. This modification was based on an exponential relationship between total element intake and body weight which we derived from data tabulated in the ICRP Publication 23, Ref- . erence Man (ICRP74). Activity would have been ingested directly with meals at Utirik Is- land during breakfast, lunch, and dinner on March 2, 1954, due to fallout on plates, on food preparation areas, and on the food itself. As mentioned previously, Sharp reported that fallout particles were not visible to the eye at Utirik Island (0C68). Fallout activity was measured in cisterns even though cisterns were reported as covered, which indicated to us that BRAVO dust may have contaminated the surface of covered food. Essentially, our estimates indicate that the majority of the BRAVO activity feil during the time breakfast was prepared and eaten. Assuming the same food eating and preparation areas as at Rongelap, and the same family size, then about 30 mg of BRAVO dust was ingested with the breakfast meal at 24 hours post-detonation. Resuspension followed by redeposition was considered secondary to direct deposition prior to and during breakfast. Our estimates of particle deposition velocity and reports of resuspension factors (ICRP80) indicate that the entire fallout would have to be resuspended into the air many times over in order to make resuspension an important pathway for internal thyroid dose. Dust falling from the cloud and ingested with lunch and evening meals at Utirik was rrr mas SGi0) 68 - 50 -