Review of the gastrointestinal absorption rates of cesium in human and animals from food products and soil particles

After the Fukushima Daiichi Nuclear Power Plant accident in 2011, public health concerns have arisen about internal exposure to the radioactive nuclides from ingestion of contaminated food products and soil. Internal exposure dose is estimated from the amount of ingested radionuclides as committed effective dose by ingestion using the ICRP internal dosimetric models. The models take account of various parameters such as gastrointestinal absorption rate (f₁). The ICRP recommended f₁ value of 1 for cesium (Cs) in any kind of chemical forms. However, previous studies have shown, for instance, Cs which strongly adsorbed to clay minerals is difficult to be extracted; therefore, the absorption rate of Cs in gastrointestinal tract varies depending on its existing form. Thus, more accurate f₁ values for Cs in different forms are important in order to estimate physiologically more realistic internal exposure dose. In this study, we review previously published research on Cs absorption rates in humans and animals from food products and soil particles, and compare the f₁ values among different existing forms. The f₁ value for Cs varies among different existing forms (studied samples containing Cs). For example, f₁ for humans has been reported to have a wide range of values between 0.08 and 1.0. Nevertheless, the data for f₁ are still limited. In order to estimate internal exposure dose of Cs more accurately, it is important to accumulate data on f₁ for various samples and construct an f₁ database for Cs. (author)