Countermeasures for reducing the transfer of radiocesium to animal derived foods.

The nuclear reactor accident in Chernobyl stimulated new discussions and experiments on the question, how and to what extent the radiocesium-concentration in animal derived foods can be reduced. In a brief review this paper describes the use of two groups of feed additives as already applied in laboratory experiments during the period of atmospheric atomic weapons tests to prevent radiocesium absorption in the gastro-intestinal tract: 1) Iron (III) -Hexacyanoferrates and 2) Clay minerals. In the post-Chernobyl-period pilot studies were initiated to test similar feed additives under practical farming conditions with "naturally" radiocesium-labeled feedstuffs. Since then it is obvious that the colloidal Prussian blue analogue Ammonium-Ferric-Cyanoferrate (AFCF) can be considered as a leading antidote against radiocesium, while Bentonite or Bolus alba are 88-266 times less effective, when compared on a weight basis. Additionally clay materials cause losses of minerals and trace elements and pose logistic problems when feeding millions of large animals. Because of the small doses needed AFCF appears as a substance of choice to reduce radiocesium burdens in animal derived foods, which gained full recognition by health authorities in W-Germany and Austria supported by an official clearance for the use as feed additive.