Deposition and retention of inhaled aggregate 67Ga2O3 particles in beagle dogs, Fischer-344 rats, and CD-1 mice

Deposition and retention of inhaled 67Ga2O3 aerosols were measured in ten beagle dogs to provide reasonable estimates for human deposition and in Fischer-344 rats and CD-1 mice to estimate lung burdens in small animals frequently used in toxicological evaluations. Aggregated particles of 67Ga2O3, 0.1 micron mass median diameter (MMD), were produced using heat treatment of 67Ga tetramethylheptanedione. Whole-body counting and gamma camera imaging were used to measure deposition. Pulmonary deposition in dogs was measured as 25% of the inhaled particles for the 0.1 micron particles. Tracheobronchial and nasopharyngeal deposition were much lower, 7% and 7% respectively. Pulmonary deposition of 0.1 micron (MMD) particles was calculated as 10% and 11% of inhaled particles in Fischer-344 rats and 15 and 20% in mice for two separate nose-only exposures of each species.