AQV AG dp. Robert A. Conard Medical Dapartment Brookhaven National Laboratory Upton, New York 11973 BEST COPY AVAILABLE Dear Eob: I have macs a reasonable literature search and have talked to a number of individuals who were involved in the test program concerning possible exposuras at Utirik. Atl of the external exposure data that I can find ara contained in the report NYO-4623 el.) by Greglin and Cassidy of HASL. Related information and data on strontium-$0 levels are contained in Gordon Dunning's 1657 report, The HASLdata are shown on the attached graph. The four sets of measure- ments do follow a reasonable T7-1-* decay and when extrapolated back to one day after tha test they agree with the value of 340 mrads/h given in the Dunning report. The exposure can then he estimated hy integrating the T71.2 function ior thes desired perlods. Ali indications point to arrival of the debris about 24 hours after the test. The exposure on the following day would be about = rads. The natives were then removed from the island and did not return for 3 months. The integrated exposure after returm from 90 days to infinity would be about 17 rads, of this about 5 rads would be delivered in the first year after return. This integral tends to overestimate the dose since it does not allow for weathering, The only indication that we have for estimatiny this effect is the data for Rongelap. If have tabulated the dose rates calculated from the T-1.2 law and compared those with the values actually measured. This table is attached. If would appearthat the overall exposure after the return could be a factor of & less than the calculated valua. IT believe that these estimates are reasonably good and that they are the best that we could make with the available cata, Regards. sincerely, LS cc: W. Burr, BER, w/enc. PF SGOGhE Jobn ff, Harley, Director Health and Safety Laboratory +vOSo