fnMl vegetation is eaten in a small area or over a large one, the quantity of fission produsts ingested is proportional to the area of plant surface eaten rather than the groundevered, as long as the deposition was similar and the animals ate in the same mamer. One might assume this for a sheep. For humans, an effective (biological + radioactive) half life of 6 days is observeds thus the biological half life is scmewhat more than simmly equal to the radioactive halflife as is here asaumed. Thus 608X757 = ad Set, If this applies here, both a lower initial uptake and lower total dose are implied by a given activity measured in the thyroid. The thyroid dose calculated here imy thus be a generous estimate, On the other hand, a lower uptake figure would put the figure of grasing and retention rate assumed still further in disagreement with the figure for ground consentre- tion based on the dose rates measured in the area. Using the values of air dose rate ami q which have been discussed, one may estimate the dose to the sheep from Shot 2 az was done in ref (1). Here the dose rate at 2 hrs was 500 mr/hr. At 3.5 hours, this is then ey With n= 1.2, this oguals 260 mrfhr, and u(t,) © 87(260) = 2300 pe/tt” as in ref (1). Then ~9- ae, noe ARCHIVES