Age-dependent variation of selenium-75 biokinetics in rat

Substantial levels of selenium-79 (79Se) in radioactive waste from the nuclear fuel cycle, may result in a significant collective dose commitment following release into the environment. Few data are available from which the effective dose equivalent among subgroups of the general population can be made. Accordingly, whole body retention and organ content were studied in neonate, adult and pregnant rat following oral contamination with 75Se. The results for whole-body retention conformed to a two-component exponential with terminal biological half-time of about 40, 30 and 20 days in adult male, neonate and pregnant rat, respectively. The highest concentrations of Se occurred in the liver, kidney, and testis. Influence of Se kinetics as a function of age and physiological development on dose estimates are discussed. Results were consistent with current dosimetric models but suggested that the testis should also be included.