eance of this level in terms of hazard remains to be considered. As will be discussed below, the still more important problem of the significance of exceeding the MPC is quantitatively incapable of definition at present. The RAND Project SUNSHINE Report created an idealized model for calculating the long-term hazard due to strontium-90. The essen- tial sections needed for the problesas considered in this report are quoted below: "Neglecting the question of biologically effective dosages, the parameters necessary for assessing the hazard on a world-wide scale are: "1. The fraction of strontium-90 available for distribution as a function of type of weapon, condition of burst, and meteorology. "We assume high-altitude bursts, with the immediate area of ground zero receiving no more than its proportional share of the fall-out debris....." (Uniform world-wide distribution of the available strontium-90.} "2. Atmospheric or other natural storage mechanisms which might allow appreciable strontium-90 decay before it becomes available to humans. "Whether strontium-90 is stored in the atmosphere or in the biosphere, this consideration is not likely to increase our estimate ....” {of the number of airburst bombs to create a world-wide hazard).... "by more than a factor of two. "3. Availability of strontium-90 in debris for transfer to the biosphere. "We believe the bulk of the strontium-90 to be plated out on the surface of the debris particles and also scavenged out in solution by rainfall." {On this assumption}...."it should be readily available for take-up by the biosphere. If our reasoning is incorrect and the strontium-90 is con- 110