177 



participated In makinq detailed measurements of th« 

 concentrations of both naturally-occurring and man-nade 

 radionuclides in the disposal areas, examining and evaluating the 

 perfomemce of the waste packaging in the marine environment, emd 

 evaluating the state of the environment to determine if there was 

 a threat to human health through various marine transport 

 pathways. 



nie studies found that the transport and uptake of 

 radionuclides in the food chain was dependent on the 

 radioisotope. Some radioisotopes are not as easily availzible for 

 bioaccumnlation/bioconcentration by plants and animals in the 

 food chain* For example, many radionuclides (such as plutonium) 

 adsorb to the ocean sediment. Such radioisotopes are much less 

 available to marine organisms, except for those benthio (bottom- 

 dwelling) organisms that ingest this sediment. In contrast, 

 8trontitsa-90 is highly mobile, and would therefore be more 

 available to pelagic (noa b otto m dwelling) organisms such as 

 pleuikton and salm«m. 



Even for those radionuclides that are more easily talcen up 

 by organisms in the food chain, however, the dilution factor in 

 the ocean can reduce the risk of uptake. This would make low 

 concentrations of soluble radionuclides, such as strontium-90, 

 less of a threat to the food chain. 



Another item to consider when evaluating the potential 

 threat to human health and the environment is the half life of 

 the radioisotopes found there. Many isotopes released into the 



