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.or years. As most nuclear plants are being built along rivers or tJie sea, the 

 aquatic environment is the most vulnerable. 



Nuclear shipping presents an even more direct threat to the aquatic environ- 

 ment. Not only does it discharge fission products into the water, especially during 

 warmup, but a nuclear vessel carries all its radioactive power source and radio- 

 active wastes with it. and in case of accident, the entire amount eventually may 

 go into the ocean. Two U.S. and one Soviet nuclear submarine have already been 

 lost, with millions of curies of fission products on board. Although the reactors 

 of these vessels are strongly contained so as to prevent accidental release, it 

 seems likely that over many years these corrosive radioactive wastes, vpith half- 

 lives of thirty, a hundred, or a thousand years, wUl escape into the sea. Colli- 

 sions in closed haribors, where most such accidents occur, could endanger large 

 population centers and result in closure of a harbor to commercial activities 

 for months or years. 



From these sources — continued fallout, efiiuents and wastes from nuclear power 

 and nuclear shipping — we see the prospect of steadily rising radioactive pollution 

 of the ocean for several decades. During the next ten years, there will be a ten- 

 fold increase in the production of radioactive wastes and, as yet, there are no 

 international agreements limiting the disposal of these wastes into the oceans. 



So violent ai'e the disagreements among scientists regarding the biological 

 hazards of radioactivity, that the general public has become quite confused. Citi- 

 zens' groups in the U.S. have succeeded in blocking the construction of several 

 nuclear power plants and are fighting legal battles against several others. The 

 power companies have counterattacked by a massive advertising campaign to 

 persuade the public that nuclear power is safer and cleaner than conventional 

 power. 



What are the facts? 



As usual, they are complex enough to provide arguments for both sides. 



Many aquatic organisms concentrate radioactive elements. Oysters, for ex- 

 ample, have been observed to concentrate zinc-65, a common fission product, 

 by a factor of 250,000 over its level in the surrounding water, and cobalt-60 by 

 a factor of a million. Certain edible seaweeds concentrate iodine-131. Other 

 typical radionuclides which may be avidly incorporated by aquatic organisms 

 are tritium, chromium-51, iron-59, manganese-54, as well as the familiar cesium- 

 137 and strontium-90. Some investigators point out that though the concentration 

 factors may be high, the absolute amounts of the radionuclides in sea animals 

 and plants are still small, and that one would have to eat very large amounts of 

 any species in order to exceed the "allowable limit" for a particular isotope. A 

 scientist studying zinc-65 concentration in oysters near the Humboldt Bay nu- 

 clear reactor in California claimed that one would have to eat nothing but 

 oysters in order to exceed the "allowable limit" of zinc- 65. 



Other scientists insist that many of the present limits are set too high, that 

 they are based on ignorance of the detailed, or long-term effects of the radio- 

 nuclide. For example, more recent studies of zinc-65 in rabbits have revealed 

 that though the animals appeared well after small daily doses for several 

 months, more sensitive studies showed deleterious effects on a number of pro- 

 teins, on blood clotting and on immunity from disease (3) . 



In humans, the allowable limits of radiation have been reduced progessively, 

 as effects have been observed at lower and lower levels. For example, the per- 

 mitted total body dose to radiation workers was set at 2500 rem/yr in 1902 

 (this is about three times the mean lethal dose, if given all at once) ; it was re- 

 duced to 100 in 1925, to 25 in 1936, to 5 in 1955 ; and Gofman and Tamplin be- 

 lieve it should be reduced now to 0.5, which is just the value that the previous 

 downhill slope would predict for 1970 ! (4) 



Gofman and Tamplin, vocal critics of the present radiation standards, have 

 compiled voluminous evidence that there are increased rates of cancer and 

 leukemia at currently permitted radiation levels (5). Other experts have denied 

 this and supported the concept of a "threshold" radiation dose below which no 

 ill effects occur. Against the "threshold" concept and suporting the Gofman and 

 Tamplin view, is a recent study by Stewart and Kneale, in England, showing that 

 children whose mothers had x-rays taken while pregnant are more likely than 

 other children to develop cancer, and that the probability increases with the 

 number of x-ray pictures taken (6). The radiation dose in these cases is ex- 

 tremely small and, until the time of this study, were considered completely safe 

 for humans at any age. It appears now that unborn babies and infants may be 



