seeker; the hazard is the development of bone cancer. Because of the nature of its fission product precursors, it is believed that the Sr-90 will probably plate out on the particles present in the explosion cloud; and, hence, when the particles: fall out the strontium will be readily available for solution in water and uptake by plants. Various assumptions and features of the model adopted in Sunshine The Sunshine are the following. (1) Model | That all of the Sr-90 formed is uniformly distributed over the surface of the globe. (2) That there is no atmospheric storage mechanism which will permit the Sr-90 to decay significantly before it is deposited on the surface, (3) That the deposited material is completely available for incorporation into the biosphere. (4) That the bones of an individual growing in an environment having a given ratio of Sr-90 to natural strontium will contain Sr-y0 and natural stronium in the same ratio (no isotopic fractionation). (5) That the arount of agriculturally available natural strontium per acre is 60 pounds, (6) That the normal U.S. adult contains 0.7 g of strontium in his bones. (7) That one microcurie of Sr-90 per adult individual is the maxinun amount which can be retained safely in the body. On these bases, and from the fact that one kiloton of fission explo- Fi rs forms one gram of Sr-90, it was concluded that the minimum rnucicar mew Pa ped Fa Evaluatio n of Hazard sion

Select target paragraph3