Exposure to131I-Labeled Viscose Rayon Fibers

Lung clearance has been studied, with external scanning, in 20 living rats after inhalation or intratracheal injection of viscose rayon fibers labeled with radioactive iodine (131I). The clearance rates after both methods of administration appear to occur in two phases. The initial rate of clearance for both modes of administration takes place with a half-life of about two to four hours. The second phase of clearance was much slower after aerosol inhalation than after intratracheal injection. The difference in clearance rates between the two modes of administration became significant 32 hours after exposure. The data suggest that, after aerosol inhalation, a significant amount of particles is deposited in peripheral lung areas, while approximately the same range of size fibers, if injected intratracheally, are deposited within the reach of the mucociliary transport mechanism.