day the ratio of doses is about 1.7. Table Four indicates the amount of ingested fissiou product activity to produce one rad dose to the lower large intestine. % Analyses of past data strongly indicate the quantity of fallout material taken in for times immediately following a detonation: (a) by inhalation is very much less than by ingestion (unless of course one does not eat or drink), and (b) may come from surface contamination of the food rather than by the soil~plant~animal cycle. How much intake is actually permitted depends upon many factors including the essentialness of the food and water to sustain life, and onets philosophy of acceptable biological risks and damages in the face of other possible hazards such as mass evacuation. By using Table 4 and Figure 7, an estimate may be made of the radiation doses that might result from the ingestion of a given amount of fission product activity. In determining how much actual ingestion, and thus the radiation doses that might be permitted, reference may be made to Table 5 which suggests the biological effects from certain doses. Such evaluations as attempted here are necessary and valuable for planning purposes, but once the fallout occurs the emergency of the situation may preclude immediate analysis of the food and water supplies. Further, the abstinence from food and water because it might be contaminated could not be continued indefinitely. Therefore, the following three common-sense rules are suggested: 1. Reduce the use of contaminated food and water to bare minimum until adequate monitoring can be epee - 23 - am