- h ' 



centimeters, or for convenience as kilograms x 10 which assumes 

 a specific gravity of one for the wet weight of fish. 



The left-hand side of the above equation Indicates the allow- 

 able total quantity of an element ingested by man in mlcrocurles 

 per week; the right-hand side indicates an identical quantity 

 accumulated in seafood living in contaminated water. It is known 

 that the efficiency of the assimilation of elements from solid 

 material is less than the efficiency of the assimilation from 

 water, but this effect is neglected in our considerations. 



If we assume a fish consumption of 1.5 kilograms per week 

 the PSC would equal the MPC in the above equation for those ele- 

 ments having a concentration factor of one. As the concentra- 

 tion factor in the marine organisms Increases It is necessary 

 to either set lower limits for the PSC or to Insure that less 

 than 1.5 kilo of seafood living in the contaminated water Is 

 caught and eaten by an individual. The PSC for the various 

 elements are listed In Table I and the diluting volumes have 

 been recalculated on the basis of these concentrations. Phos- 

 phorus now turns out to have the greatest required diluting 

 volume with lodine-131 a close second. Both of these elements 

 have half lives so short that it is likely that each would be 

 decayed to 0,1^ of the supply before reaching the environment. 

 It does indicate, however, that assurance should be had that at 

 least 10 half lives of decay should occur for these elements be- 

 fore sea disposal. Using the PSC as the basis for required di- 

 lution, strontium 90 would require a square mile of seawater 10 

 meters deep, copper about half a square mile, and cesium and iron 

 less than a tenth of a square mile. 



In conclusion it should be re-emphasized that several factors 

 of safety are Inherent in these computations, but it should also 

 be emphasized that uncertainties exist concerning the concentra- 

 tion factors and the effects of radioisotopes on the marine biota. 

 One factor of safety is that we have selected a rate of seafood 

 consumption which is far greater than the national average but 

 which is realistic in terms of the quantities eaten by the 

 Japanese and perhaps by some coastal U„ S, communities. An- 

 other factor of safety is that elements are assimilated less 

 readily from solid food, such as fish, than they are from 

 drinking water and we have assumed these rates of assimilation 

 to be equal. A third and more important factor of safety is that 

 these calculations assume that all of the fish eaten comes from 

 the small area of the ocean which is used for the disposal of 

 these wastes. Still another factor of safety lies in the sim- 

 plified approach we have taken to compute the" diluting volume. 

 We have assumed that all of the radio elements produced in l8 

 months at Oak Ridge would be introduced into a single disposal 

 area simultaneously, an assumption which is obviously falacious. 

 In any actual waste disposal at sea the rate of supply would be 

 much slower than this and since currents would be washing past 

 the location constantly the volume of water available for di- 

 lution would be enormously greater than the volume which 



