SLIDE 21 Radioactivity intake estimated from excreta. The fraction of an initial 131y activity intake by ingestion that would be eliminated by an adult on a given day post the intake was calculated by two methods. One was a model by Johnson (Jo81) and the other was a model used by ICRP (ICRP79). Both models had feedback incorporated into the estimate of the fraction of initial intake. Both were solved using catenary compartment kinetics and both led to similar valyes for elimination of I by a reference man. Based on 0.48 kBq (1.32 x 10 wCci) in adult urine intake was estimated for 13 I.the 17th day post intake, a 3,440 kBq (93 |e Ci) The intake of 3,440 kBq (93 #Ci) Wag used as a normalization point. That is, once the relationship between I and other nuclides in fallout was determined by us, then the contr}pution to thyroid dose from all radiotiodines was estimated while keeping the I intake at 3,440 kBq (93 Aci). Whole-body retention functions were given hy ICRP (ICRP72) for strontium -5 -4 and barium as f llows: Rg(t) = 0606-8 25€49,299(¢40.20)-+18(0, 555¢~6+5#10” tag g45e-2s6x10" ty ’ Rea (t) _ _ -4 _ = 0.38e70°/9t40 6191 (t+0.007)70 9237 (0.56407! 09K10 “tig 436074 36x10 4 ty | where t is in days and R(t) is the absorbed fraction remaining on day t. The fecal to urine ratios for excretion of absorbed Sr and Ba wers 0.25 and 9.0, respectively (ICRP72) Correcting for, 45 days of decay, the 5 activity absorbed was estimated to be 2.3 x 10° Bq (0.62 pCi) and the ! Ba activity absorbed was 6.1 x 10° Bq (16.4 ACi). If fallout was directly ingested as a single intake of dust at 0.5 days post detonation, then the intake of 1408, 905, or 13ly should be in a ratio similar to one estimated by us by a different approach. The fraction of ingested iodine absorbed into blood was taken as 1.0, the fraction of ingested strontium absorbed into blood was taken as 0.2 and the fraction of ingested barium absorbed into blood was taker as 0.06 (ICRPO8} The tpeake ratios we obtained from urine results for I relative to “Sr or Ba are 28 and 0.34, respectively. The hypothetical ratios are 8.5 and 1.2 based on unfractionated thermonuclear fission data. Thus the urine derived Batio of activity is a factor of 3, kgwer than the hypothetical ratio for ~“Sr and a factor of 3 higher for Ba. ESTIMATE OF ACTIVITY INGESTED (RONGELAP) Activity Nuclide 1317 89 Sr “Ba 1, ; re aes Ingested Bq 3.4x10°5 1.2K10 1.010” Iodine Activity* —— Nuclide Activity 1.0 8.5 1.2 *Thermonuclear neutron fission and 5 hours post detonation. oR