APPENDIX VI 

 PERMISSIBLE SEA WATER CONCENTRATION^MONITORING OF DISPOSAL AREAS 

 B.H. KETCHUM and W.A. CHIPlvIAN 



In considering permissible seawater concentrations of various 

 radioisotopes the ultimate criterion is the hazard to man. In the 

 absence of evidence to the contrary we have assumed that the hazard 

 to the marine biota is probably no greater than the hazard of an 

 equivalent body burden of the Isotope to man, and some evidence 

 indicates that the body burden of marine organisms can be greater 

 than that in man without danger. Presumably therefore water which 

 would be safe on its radioisotope level for man to drink would 

 also be safe for fish and other members of the marine biota to 

 live in. 



The radioisotope hazard to man has been carefully evaluated 

 In establishing the maximum permissible concentration (MFC) for 

 drinking water. These values have therefore been used as the 

 basis for our calculations. This has the additional advantage 

 that any change in the MFC would automatically produce a com- 

 parable change in our suggested permissible concentrations for 

 seawater. 



As a first step in the evaluation of the present magnitude 

 of the problem of low level waste disposal we have compared the 

 total supply of radioisotopes with the maximum permissible con- 

 centration for drinking water in order to determine the volume 

 of water necessary to achieve such a dilution. The results of 

 this tabulation are given in Table I. The entire amount of 

 radioisotopes (exclusive of sealed sources) shipped to licencees 

 east of the Mississippi River plus Texas and Louisiana between 

 January 195^ and September 1957 have been used as an index of 

 the rate of supply (AEC, 1957). 



The isotope requiring the maximum dilution in Table I Is 

 iodine 131 which would require 3.5 x 10' cubic meters. This 

 volume would be contained under one nautical square mile of sea 

 surface area in water that was ten meters deep. Since, however, 

 lodlne-131 has a half life of only eight days it is obvious 

 that it would be largely decayed before disposal in the sea. For 

 elements with longer half lives strontium is the most critical 

 one and would require a diluting volume of 2,i| x 10° cubic meters; 

 a volume which would be contained under a surface area of somewhat 

 less than J. of a square mile 10 meters deep. 



All of the other radioisotopes listed in Table I would re- 

 quire far smaller volumes for adequate dilution to achieve the 

 maximum permissible concentration for drinking water. It 

 appears, therefore, that the present production of radioisotopes 

 as listed in Table I could all be dispersed directly in a small 

 area of coastal waters with no hazard to marine resources or to 

 man. Actually, because of other methods of disposal, and of the 



