CHEMICAL METHODS FOR REDUCTION OF THE TRANSFER OF RADIONUCLIDES TO FARM-ANIMALS IN SEMINATURAL ENVIRONMENTS

The same chemicals can be used for reduction of radionuclide transfer to animals whether kept on farms or grazing in semi-natural and natura l habitats. However, different techniques are required for administrat ion of the active compounds. Dairy ruminants may be treated effectivel y by inclusion of chemicals in supplemental concentrates. Practical ex perience gained after the Chernobyl accident has shown that both clay minerals and hexacyanoferrates are effective in preventing high radioc aesium levels in animal products. Chemicals such as bentonite clays an d CaCO3, used for reduction of Cs-137 and Sr-90 transfer respectively, must be fed in hectogram quantities and are only practical for dairy animals in semi-natural ecosystems. Salt licks and sustained release b oli with hexacyanoferrates as caesium binders have been developed and used successfully after the Chernobyl accident for meat producing catt le, sheep and. reindeer which graze freely for extended periods. Daily doses of 25-300 mg in sheep and 250-2000 mg in cows reduces Cs-137 ac cumulation 2-10-fold. Binders for Sr-90 have not been tested in grazin g animals. Stable iodine could be provided in salt licks and indwellin g rumen boli at rates required to block radioiodine uptake by the thyr oid gland. Boli and salt licks are highly cost effective in reducing d oses to man when compared to interdiction of food from farm animals.