When Norway discovered radioactive caesium in grazing reindeer in 1992, the search was on for effective countermeasures and protective actions. The long-lived radionuclide migrates through the food chain and accumulates in meat and milk products. Norwegians agricultural authorities focused on a method known as "Prussian Blue (PB)", a chemical compound known to reduce the rate of bodily caesium absorption. Rather than being taken up in the bloodstream, the caesium binds to the PB and is excreted. By late 1992, the compound was being routinely given as a feed additive to more than 200,000 sheep, reindeer, and cattle, recording significant reductions in contamination levels.
Norways experience underpins a global project that successfully applies the PB method to livestock in Chernobyl-contaminated regions of Belarus, Russia, and Ukraine. Financed by Norway and technically supported by the IAEA and Food and Agriculture Organization, the project brought together national agricultural institutes and authorities for collaborative studies and field trials. The trials in Belarus, Russia, and Ukraine -- which confirmed that PB reduces the levels of contamination in meat, milk, and in crops fertilized with the animals manure led to the compounds approved widescale use for livestock in the three countries in early 1993.
The move directly benefited about 50,000 farmers in affected regions, and overall national agricultural economies. Among agricultural countermeasures prompted by the Chernobyl accident, the PB project has proved to be the most cost effective. In Belarus, an annual investment of US $50,000 has saved around US $30 million worth of milk and meat production a year. National authorities there still apply the method and credit its use, in combination with other steps, for the steady decline of areas where caesium-137 in commercial milk samples exceeds permissible levels.
--For an overview of post-Chernobyl agricultural countermeasures and the PB project, see the IAEA Bulletin Chernobyl edition, Chernobyl Forum Report and the report on reducing caesium contamination of food products.