137Cs and 210Po in Pacific walrus and bearded seal from St. Lawrence Island, Alaska

The activity concentration of Cesium-137 ( 137 Cs) and naturally-occurring Polonium-210 ( 210 Po) were measured in the muscle tissue, kidney and liver of Pacific walrus ( Odobenus rosmarus divergens ) and bearded seal ( Erignathus barbatus ) collected by native hunters from the Bering Sea during May 1996. The mean 137 Cs concentrations in muscle, liver and kidney of Pacific walrus were 0.07, 0.09 and 0.07 Bq kg −1 ( n = 5, wet weight), respectively, and 0.17, 0.10, and 0.17 Bq kg −1 ( n = 2, wet weight), respectively, in bearded seal. In general, 137 Cs tissue concentrations are significantly lower than those previously reported for mammals from other regions. By comparison, 210 Po activity concentrations are more variable and appear to be higher level compared with mammal data from other regions. The mean 210 Po concentration in the muscle tissue, liver and kidney of Pacific walrus ( n = 5, wet weight) were 28.7, 189, and 174 Bq kg −1 , respectively. This compares with 210 Po concentration values ( n = 2, wet weight) of 27, 207 and 68 Bq kg −1 measured in the muscle tissue, liver and kidney, of bearded seal, respectively. Estimated concentration factors—as defined by the radionuclide concentration ratio between the target tissue to that in sea water—were two to three orders of magnitude higher for 210 Po that those of 137 Cs. We conclude from radiological dose estimates that ingestion of 137 Cs in foods derived from walrus and seal will pose no threat to human health. This work has important implications for assessment of risks of Alaskan coastal communities concerned about the dumping of nuclear waste in the Russia Arctic.