Decontamination of radioactive milk--a review

The Chernobyl nuclear reactor accident in Russia in 1986 has further revealed the susceptibility of the environment to radioactive contamination. This can have serious implications for the safety of milk as well as other foods. Global fallout and other isotope releases can threaten to increase the radionuclide levels in milk alarmingly, and thus make it unfit for human consumption. Perception of such fears in the past resulted in considerable research efforts being directed towards radioactive decontamination of milk by different means. The holding of milk and milk products long enough to deactivate certain radioisotopes prior to consumption, conversion of milk into butter, and manufacturing cheese by using modified processes are some of the approaches in minimizing the radioactivity risk to consumers. Extensive studies carried out in the USA have shown that though somewhat expensive, ion-exchange treatment of milk in large-scale, automated plants can eliminate 90% or more of the radionuclides of concern, i.e. strontium-90, and iodine-131, and much of caesium-137. Various factors affecting the efficiency of the ion exchange process and properties of the treated milk are reviewed. Other processing techniques such as electrodialysis are also briefly discussed in relation to removal of radionuclides from milk.