A review on speciation of iodine-129 in the environmental and biological samples

As a long-lived beta-emitting radioisotope of iodine, 129I is produced both naturally and as a result of human nuclear activities. At present time, the main part of 129I in the environment originates from the human nuclear activity, especially the releases from the spent nuclear fuel reprocessing plants, the 129I/127I ratios have being reached to values of 10−10 to 10−4 in the environment from 10−12 in the pre-nuclear era. In this article, we review the occurrence, sources, inventory, and concentration level of 129I in environment and the method for speciation analysis of 129I in the environment. Measurement techniques for the determination of 129I are presented and compared. An overview of applications of 129I speciation in various scientific disciplines such as radiation protection, waste depository, and environmental sciences is given. In addition, the bioavailability and radiation toxicity (dose to thyroid) of 129I are discussed.