Abstract
Absorption of 228Th, 232U, 233U, 237Np, 237Pu, 238Pu, 239Pu, 241Pu, 241Am, 244Cm, 252Cf and 253Es from the gastrointestinal tract was measured in neonatal rats gavaged with solutions or suspensions of these actinides. Particle size, valence, chemical form and animal age all influenced actinide absorption. The neonatal rat and guinea pig absorbed about 100 times more 238Pu than the adult: the newborn swine absorbed 20 times more Pu than either the newborn rat or guinea pig. In addition to the fraction absorbed, a substantial fraction of radionuclides administered in "soluble" forms was retained for several days within the mucosa of the small bowel.