Observation of some anomalies in the ICRP metabolic model of uranium

A simple and sensitive analytical method was developed for determining the concentrations of uranium (236U) in biological and environmental samples. The minimum detection limit (M.D.L) of 0.08 ng uranium (0.1 Bq of 236U) in a sample was obtained with this method. Data on daily intake (through diet, drinking water and air), the excretion (through urine) and organ burdens of uranium were obtained for human subjects living in Bombay (India), and were employed to obtain important human metabolic parameters of U such as, gastrointestinal absorption factor (f1), excretion ratio and biological half-lives of uranium retained in various human organs. The study showed that the f1 factor for uranium available to humans at dietary level (0.5-5 ug.d-1) is 0.016, which is much lower than 0.2 suggested in ICRP 30. The biological half-lives, of uranium stored in kidney and muscles were estimated to be much longer than those proposed by ICRP. (author)