Natural-series radionuclides in traditional North Australian aboriginal foods

Activity concentrations of the radionuclides Ra-226, Pb-210, Po-210, U-238, U-234, Th-230, Th-232 and Ac-227 were measured in edible flesh of traditional Aboriginal food items from the Magela and Cooper Creek systems in the tropical Northern Territory of Australia. Fish, buffalo, pig, magpie goose, filesnake, goanna, turtle, freshwater shrimp and freshwater crocodile were studied Activity concentrations in water were also measured to enable the calculation of concentration ratios (CRs). For most edible flesh samples, activity concentrations followed the approximate order. Po-210 much greater than Ra-226 > Pb-210 > [U-234 similar to U-238] > [Th-230 similar to Th-232]. The Po-210/Pb-210 activity ratio was particularly high (greater than 100) for pig flesh. CRs for fish species fall into two groups. Group 1 (bony bream and sleepy cod) had CRs about five times higher than for group 2 (eight other species). CRs for turtle flesh were similar to those for fish in group 1, while those for turtle liver were about a factor of 10 higher. CRs for magpie goose, filesnake, freshwater shrimp, goanna and crocodile flesh were also of the same order as for fish in groups 1 or 2. Calculations of dose resulting from release of wastewaters from uranium mining operations in the region show that the dominant pathway would be uptake of radionuclides, especially Ra-226, by freshwater mussels, followed by radionuclide uptake by fish. (C) 1998 Elsevier Science Limited. All rights reserved.