75Se transfer via placenta and milk, distribution and retention in fetal, young and adult rat

In the future 79Se, a component of nuclear wastes, may increase the dose equivalent to members of the public. Following ingestion of 75Se by pregnant rats, retention in the organs of fetuses and young rats was measured at several time intervals. Transfer coefficients for the fetus and the newborn during lactation were compared by cross-fostering using contaminated and uncontaminated dams. For a litter, the transfer of selenium via the placenta at the end of gestation was 12.7 ± 1.59% of the initial activity; at the end of lactation the transfer via placenta and milk was 21.27±2.56% and the transfer via milk alone was 12.5±0.88%. For each organ examined, the selenium content was systematically lower in fetal and young rats than in adults. Selenium was concentrated in the testis, the liver, the kidneys and the spleen. The biological half-time for pregnant and young rats was 17 and 37 days respectively. (author)