A pilot study on the transfer of 137Cs and 90Sr to horse milk and meat

The radiological assessment of the impact of nuclear weapon's testing on the Semipalatinsk Test Site (STS) on the local population requires comprehensive site-specific information on radionuclide behaviour in the environment. However, information on radionuclide behaviour in the conditions of the STS is rather sparse and, in particular, there are no data in the literature on parameters of radionuclide transfer from feed to horse products proofed to be important contributors to the internal dose to the local population. The transfer of Cs-137 and Sr-90 to horse milk and meat was studied under laboratory and field conditions: in controlled experiment with three lactating horses maintained in the Kazakh Agricultural Research Institute, and in field measurements of horse products taken from horses grazing at the Semipalatinsk Test Site. The equilibrium transfer factors from feed to horse milk and meat were estimated to be 0.012 d 1(-1) and 0.035 d kg(-1) for Cs-137 and 0.0022 d 1(-1) and 0.003 d kg(-1) for Sr-90, respectively. The biological half-lives were approximated by a sum of two exponentials amounting to 3 (85%) and 15 (15%) days for Cs-137 and 3.5 (70%) and 100 (30%) days for Sr-90. The highest Cs-137 transfer has been found to be to spleen, followed by lung, heart, muscles, kidneys, intestine, and finally skin and bones. For Sr-90, the maximum activity concentration was observed in bones; contamination of other tissues is rather uniform except for liver and intestine with a factor of about 2 higher than muscles. (c) 2005 Elsevier Ltd. All rights reserved.