however, it may tend to concentrate them in the bottom sediments from 

 which they may be returned to the water or taken up by bottom-living 

 food organisms. 



Biological effects : A number of elements are concentrated in the 

 bodies of organisms by several orders of magnitude over their abun- 

 dance in natural waters. Radio-isotopes of such elements are, there- 

 fore, concentrated in man's aquatic foods. As pointed out by Ketchum 

 (1957), the concentration of certain elements by organisms, subsequent 

 migration of these organisms, and gravitational effects on their excreta 

 and remains, all combine to produce a circulation of these elements 

 which differs from the circulation of the water. This is of particular 

 importance in inshore and estuarine waters where, as shown by Ketchum, 

 there may result an accumulation of an element greater than that in the 

 source waters. Revelle and Schaefer (1957) have noted also that "The 

 time required for removal of radioactive materials from estuaries 

 will, in general, be much greater than the flushing time of substances 

 that are not absorbed by organisms or taken up by bottom sediments". 



MAXIMUM PERMISSIBLE CONCENTRATIONS IN SEA FOOD 



As we have noted above, the maximum permissible body burdens 

 of various radio-isotopes and the corresponding maximum permissible 

 concentrations in drinking v/ater as applicable to the general public 

 (calculated under the assumption that this is the only source of the in- 

 gested isotope) have been tabulated in Title 10, Chapter 1, Part 20, 

 Code of Federal Regulations, Revised 1959 (proposed). These are re- 

 capitulated in Table 2 for a number of isotopes, including the more im- 

 portant corrosion products and fission products which may occur in 

 wastes from shipborne reactors. 



Two additional considerations are required in arriving at the 

 maximum permissible concentrations in sea_food w^hich would be per- 

 mitted to originate from waste disposal operations of nuclear-powered 

 ships. The first of these involves estimation of the amount of seafood 

 which would be ingested, per unit of time, by a segment of the popula- 

 tion. The second involves allocating to ship waste disposal a certain 

 share of the maximum permissible dose w^hich man may receive from 

 the utilization of atomic energy. As has been pointed out earlier, food 

 from the sea is not the only source of ingestion of radio-isotopes, and 

 nuclear-powered ships are not the only potential source of introduction 

 of radioactive material to the sea. Therefore, it is necessary to de- 

 cide how much of the maximunn permissible intake shall be allocated 

 to the results of waste disposal from nuclear-powered ships. 



Since the maximum permissible concentrations so determined 

 apply only to that activity originating from nuclear ship operation, they 

 are actually partial permissible concentrations (ppc's) and are so des- 

 ignated in this report. 



The evaluation of how much of the maximum permissible intalce 

 should be allocated to the results of waste disposal from nuclear- 



15 



