Non-linear radionuclide transfer from the aquatic environment to fish.

Uptake of 226Ra, 232Th, 230Th, and 228Th from water, sediment, and diet sources to bone and muscle of white suckers (Catostomus commersoni) was studied in sixteen lakes in the uranium-mining district of Ontario, Canada. Fish tissues did not increase linearly with environmental concentrations. The best relationship appears to be a power function. This has implications for the accuracy of radiological dose and risk estimates for uranium mining impacts, which are often based on a linear model.