The observation by RAABEet al. (1973) of large differences between the solubilities of isotopically different plutonium dioxides, has led to the recognition of preferential etching of recoil damage as a widespread phenomenon for alpha-active radionuclides. The associated preferential solubility of the products of alpha decay, along with direct recoil ejection, are the two specific microscopic mechanisms that are documented as causes of isotopic disequilibrium in the U and Th decay series. Similarly, leaching plays a significant role in releasing 222Rn from natural substances, 222Rn being the alpha-decay product of 226Ra. The average annealing time in nature of the damage sites can be inferred from the extent of isotopic disequilibrium for different isotopic pairs in the Th and U decay chains.