powered ships can be considered in two parts. The first involves an 

 allocation to sea disposal in general. Essentially there are three en- 

 vironments from which man might receive radioactivity; these are the 

 atmosphere, the land (including food and water from the land), and the 

 sea. It is assumed here that sea disposal from all potential sources 

 should be limited to a contribution to a selected portion of the popula- 

 tion of no more than one-third of the maximum permissible intake for 

 such a selected portion of the population. This allocation is not in- 

 tended to specify the manner of subdividing the remaining two-thirds 

 between land and atmosphere. 



The evaluation of the remaining factors is somewhat different 

 for each of the major subdivisions of the marine environment. In the 

 following paragraphs the special considerations which apply to the in- 

 shore areas, to the continental shelf, and to the open sea are presented. 



Special considerations related to harbors, estuaries and other 

 inshore waters and to the continental shelf : An extremely conservative 

 approach is warranted for these waters for the following reasons. 



1. Most of the harvest of food from the sea comes from these 

 waters, including the entire harvest of some sedentary forms, such as 

 oysters, scallops, clams and seaweed, v/hich concentrate certain ele- 

 ments by very large factors. Some large segraents of the w^orld popula- 

 tion receive the bulk of their protein requirements from this part of the 

 sea. 



2. With the continuing development of atomic power, there will 

 inevitably occur a requirement for some introduction of radionuclides 

 into the inshore waters from land based establishments; the cost of 

 avoiding this may be prohibitively high. Thus only a portion of the total 

 potential receiving capacity of these waters is available for waste dis- 

 posal from nuclear-powered ships. 



3. In the case of a nuclear war, one of the least contaminated 

 sources of food will be the sea. It is, therefore, desirable to keep the 

 radioisotope contamination prior to this as far below the maximum per- 

 missible level as possible. 



Some areas of the continental shelf do not contribute materially 

 to the commercial fisheries, and hence some subdivision of this environ- 

 ment might be considered on the basis of known fishing areas. However, 

 it should be remembered that the migratory species travel throughout 

 the waters of the shelf, even though they may not be readily exploitable 

 in some areas. Also some segments of the continental shelf are not 

 now classed as known fishing areas simply because, for one reason or 

 another, they have not yet been exploited. Hence no region of the shelf 

 can be considered as completely devoid of biological significance. 



The possible introduction of radioactive wastes into the sea from 

 land based operations will result, for the most part, in contamination 

 of harbors, estuaries, and coastal waters. Hence it may be appropriate 



17 



