Radionuclides

Atomic species whose nuclei decay, each disintegration spawning daughter products that decay in turn, forming the familiar radioactive series. The food-relevant cast includes natural members such as radium and polonium from uranium and thorium decay chains, concentrated in certain geologies, and artificial additions like cesium-137 and strontium-90 from nuclear fallout. Surveillance programs test milk, produce, and seafood against strict limits, and processing factors such as cheese-making partition can concentrate or dilute them. Geology and history decide which ones matter in a given region.