UNCLASSIFIED a cee ee ce we ey een ey SUMMARY The Problem The assessment of the radiation hazard resulting from the inhalation of fallout from nuclear detonation requires knowledge of the metabolism of various types of fission- product aerosols, The kinetics of the uptake, distribution and retention in mice of two fission-product aerosols, stron-= tium (highly soluble) and lanthanum (insoluble), were studied, Aerosols of Sr85Clz and La!49C13 were generated both as liquid droplets and adsorbed on kaolin particles. In addition, aqueous suspensions of these aerosols were administered to mice by stomach tube, ' Findings It was found that the gastrointestinal tract can serve as an important portal of entry into the body for soluble fissionproduct aerosols following an inhalation exposure. This finding implies that an evaluation of the internal hazard as- sociated with an inhalation exposure to radioactive fallout must take into account those factors which influence trans port across the gastrointestinal membrane as well as the more commonly considered factors which determine transport across the alveolar tissue, £L Da 4 fF an EE BG & ' FEF wes KR re &@ Bi © b | E rm 211