wa fra a“ “e 7 Lode E es quamiin Dr. Bugher -2- ' ae Looe «= September 16, 195) My analysis of the inhalation va. oral ingestion routes of uptake leads me to believe ingestion is much the more important. Hardin Jones, rowever, believes inhalation explains his data better, If it is assumed thet oral ingestion is dominant, one would expect human activity to be lower than grazing animals’. (However, where milk is an important dietary component, avaidable data on I trans— mission through milk suggest that human thyroids would not be much lower in activity/gm than the cowst.) Laoy's data probably give only an upper limit to the average American himan thyroid activity; the actnal value is quite likely lower by « considerable factor. Wy calculations are based on LeRoy*s values. fine Scale of I-13] Ingestion To extrapolate from observed activity in duly to integrated dose from the ful] CASTLE series, an estimate muat be made of quantity of ingestion as a function of time. Preliminary data from Lynch on fallout indicate that essentially all I-131 measured in Jime and July originated from the May k shot. ‘Tbtal fallout in the U. S. from CASTLE was about 3 times that from the May ) shot, gach that total thyroid dose from CASTLE would have been three times that from the May 4 shot. In my calenlations I have assumed that all fallout in the U. 5S. from the May shot occurred on May 15, and that a continuous ingestion of I-13] was thereafter maintained at a constant mmber of fissions per day. If, on the contrary, I had assumed all thyroid activity observed in June and July was taken up on May 15, total dose would nave been higher by a factor ef about 5. DISTRIBUTION: copy LA — Dr... Bugher 2,34 - Biophysics Branch . Ba L,5,6A - BAM Files , 7 OFFICE p SURNAME p> DATE > ON mo el |.___ Form AEC-818 (Rev, 1-43) U.S. GOVERNMENT PRINTING OFFICE 16—62761-3 DOE ARCHIVES