185 



Even for those radionuclides that are more easily taken up by or- 

 ganisms in the food chain, however, the dilution factor in the ocean 

 can substantially reduce the risk of uptake. In some cases, this 

 could reduce the impact of the food chain of such soluble radio- 

 nuclides like strontium. 



Another item to consider when evaluating the potential threat to 

 human health and the environment is the half life of the radio- 

 nuclides involved. Many radionuclides released into the marine en- 

 vironment have very short half lives, of anywhere from a few min- 

 utes to a few years. These radionucHdes, when released into the 

 ocean, will both disperse and decay rather rapidly. On the other 

 hand, some of the radionuclides that may have been released in the 

 Arctic could be fairly long-lived. For example, strontium-90 and ce- 

 sium- 137 have half-lives of 28 and 30 years respectively. And many 

 other radionuclides have even longer half-lives, some of them get- 

 ting into thousands and thousands of yegirs. 



Examination of the environmental impact resulting from the 

 1986 Chernobyl accident illustrates the effect of such radiodecay. 

 In 1889, EPA entered into a cooperative agreement with the Insti- 

 tute of Biology of the Southern Seas in the Ukraine, to study the 

 transport, partitioning, and effects of Chernobyl's principal fallout 

 radionuclides on the Black Sea. In June 1990, a joint monitoring 

 survey was conducted in the northern Black Sea. TTie radionuclides 

 tracked by this effort were cesium-134, cesium-137, ruthenium- 106, 

 cerium- 144, and strontium-90. During the six years since 

 Chernobyl, all of the radionuclide concentrations have been de- 

 creasing through dilution or radiodecay until only long-lived ce- 

 sium-137 is at concentrations that are stiU easily measurable in 

 the Black Sea. 



In addition to these considerations in evaluating the extent 

 caused by radioactive contamination in the Arctic, an analysis of 

 potential impact of such radiation on human populations such as 

 the Inuit would require consideration of the dose of radiation likely 

 to be received by both an average and a maximally exposed individ- 

 ual. The maximally-exposed individuals are those that you might 

 expect to have particularly high exposure because of their proxim- 

 ity to the sources and their dietary preferences. In addition, the 

 population of individuals likely to be affected, by living near the 

 coast or consuming Arctic marine seafood, is an important consid- 

 eration in evaluating the risk posed by the contamination. In all 

 likelihood, the Inuit might very well represent the maximum ex- 

 posed individuals. 



As you can see, while EPA does have some data about the behav- 

 ior of radionuclides released generally into the marine environ- 

 ment, we know little about the specific contamination in the Arctic. 

 However, we do know the kinds of information that need to be col- 

 lected in order to assess the risks from Arctic pollution. Much more 

 information needs to be gathered in order to fully gauge the risk 

 posed to human beings and the environment by the activities of the 

 former Soviet Union. 



Potential sources of radiation from the former Soviet Union in- 

 clude disposed reactor vessels, waste drums, aerial transport of 

 radionuclides, and radioactivity entering from Russian rivers that 



