Predicting the radionuclide fraction transferred to consumption through grain foods

Data on the root uptake by wheat of three activation products, 54Mn, 65Zn and 63Ni, and two fission products, 90Sr and 137Cs, were obtained in a long-term field study. Soil-plant transfer factors calculated from these data were used to determine the amount of various radionuclides that may reach the humans through grain foods. The temporal variation of this contribution showed that the fraction of 54Mn and 65Zn transferred to human consumption during the first year was considerable, but owing to decay and decreasing uptake the gradients diminished and the accumulated fraction flattened to a plateau. In contrast, the fractions of the long-lived 63Ni, 90Sr and 137Cs transferred to human consumption were smaller and with nearly constant gradients. This study shows that the long-lived radionuclides are transferred to the same extent as 54Mn and 65Zn. In the long-term, the greatest doses from grain products are contributed by the long-lived radionuclides.