In the discussions which follow we will be concerned primarily 
with strontium 90. The hazard of other isotopes, relative to strontium 
90, insofar as uptake by marine organisms and return to man in marine 
food products is concerned, will be given by the ratio of the permissible 
sea water concentration of an isotope to that of strontium 90. Table II 
lists the number of curies of each of a group of selected isotopes, equiv- 
alent to 250 curies of strontium 90, the latter value being the suggested 
maximum yearly rate of disposal of strontium 90 into any one disposal 
area. Also shown are the quantities of each of the isotopes that would 
decay to 250 equivalent curies following containment of one month and 
of one year. 
The significance of the quantities of isotopes relative to strontium- 
90 is apparent when considering the practical problem of the disposal of 
packages containing a mixture of isotopes. Assume, for example, that 
packages containing waste of the following composition have been added 
TABLE Il 
QUANTITIES OF SELECTED RADIOISOTOPES EQUIVALENT! 
TO 250 CURIES OF STRONTIUM 90, SHOWING THE INITIAL 
QUANTITIES THAT WILL DECAY TO 250 EQUIVALENT 
CURIES ALLOWING ONE MONTH AND ONE YEAR CONTAIN- 
MENT 
lsotope Curies 
no containment 1 mo. containment 1 yr. containment 
Na 24 5.0 x 107 1024 10183 
P 31 1525 68.6 1.1 x 109 
§ 35 3.1 x 106 3.9 x 10° 5.6 x 107 
K 42 3.1 x 108 1014 10226 
Ca 45 1.6 x 105 1.8 x 105 7.5 x 10° 
Fe 59 1.2 x 103 opel) 3.3 x 105 
Co 60 6.2 x 103 6.3 x 103 7.0 x 10% 
Cu 64 5.0 x 104 102! 10201 
Zn 65 14x 10 sg 1.5 x 104 3.8 x 104 
Sr 90 250 250 250 
1131 9.3 x 102 1.2 x 104 1016 
Cs 137 9.3 x 104 9.3 x 104 9.3 x 104 
TEquivalence based upon ratios of Permissible Sea Water Concentrations. 
13 
