84 BIOLOGICAL EFFECTS OF ATOMIC RADIATION 



areas close at hand. It will require at least five years of intensive studies to provide adequate 

 understanding of the estuarine and coastal waters. 



The Open Ocean 



Significant amounts of radioactivity may be introduced into the open ocean in scientific 

 and engineering tests, through sinkings of nuclear-powered vessels, and by the disposal of 

 wastes from power reactors. At the present time, on the basis of fragmentary information, it 

 is possible to make only vague estimates of the fate of radioactive isotopes introduced in the 

 deep ocean. Too little is known concerning the circulation and mixing processes in the surface 

 layers and in the deeper, more homogeneous waters of the great ocean basins to evaluate 

 accurately either the rate of dispersal near the surface or how rapidly materials introduced at 

 great depths will be transported by mixing and vertical currents into the surface layers where 

 they will be concentrated by marine organisms. Many physical, chemical, biological, and 

 geological processes are involved and must be studied in detail. To provide the essential in- 

 formation, comprehensive oceanographic investigations need to be made by all maritime 

 nations. 



Ocean Processes 



The two programs outlined above will provide essential information on the regional 

 characteristics of the shallow estuarine and coastal areas and on the currents and mixing 

 processes in the waters of the open ocean. Alterations in physical state, together with solution, 

 precipitation, and interaction with sedimentary particles, will affect the fate of the materials. 

 Some of these processes can be studied at sea but others can be more profitably investigated 

 in shore laboratories where there are specialists and the necessary complex equipment. Field 

 and laboratory studies are also essential to establish the biological half-lives of radioactive 

 materials in marine plants and animals and the biological pathways involved in the uptake, 

 concentration, and retention of the individual isotopes. As section 3 shows, these are more 

 important than the concentration factors that have been the principal subject of study in the 

 past. 



5. Radioactive Materials Introduced into the Irish Sea and the Columbia River. 



The most important radiation exposure that a significant fraction of the papulation is apt 

 to receive from the existence of radioactive materials in the sea will probably originate from 

 fish, shellfish, seaweed, or other products consumed as food. To assure that the quantities 

 of radioisotopes consumed with these products do not exceed allowable amounts, certain limits 

 must be established for the quantities of individual isotopes that can be added to a given body 

 of sea water. The selection of suitable limits is complicated by the different behavior of the 

 radioelements under various environmental conditions, the types of foodstuffs which are 

 harvested from a specific area, the rate of consumption of these products by individuals, and 

 the contribution that other sources of radiation make to the overall exposure received by the 

 population involved. 



Where no previous experience is available for the particular area involved, permissible 

 limits must be predicted on the basis of field or laboratory observations made elsewhere and 

 on assumptions that large quantities of the marine products are consumed by individuals. It 

 was necessary for working groups of this Committee to use such criteria in the computation 



