Deposition and retention of 0.1 micron 67Ga2O3 aggregate aerosols in rats following whole body exposures.

Determinations were made of respiratory tract deposition and gastrointestinal tract burdens following whole body inhalation exposures, typical of those used in many chronic exposures; these were compared to values obtained in nose-only exposures. Fischer-344 rats were exposed in large volume chambers, in a whole body mode, to 0.1 micron volume median diameter (VMD) 67Ga2O3 particles 5 hrs/day. Deposition per unit of exposure time and retention were essentially identical following either 1 or 3 day exposures. The lung deposition of particles was 2.8 units/hr for males and 2.2 units/hr for females if the exposure concentration was expressed as 1 unit/L. These values represent a deposition of approximately 15% of the inhaled particles, similar to values obtained for nose-only exposures. Aerosol deposition per kgm body weight was 24% higher in females than males. Passage of material into the gastrointestinal tract was 1.6-fold greater for these whole body exposures as compared to nose-only exposures to the same aerosol mainly resulting from extra material ingested by grooming of the pelt. Approximately 60% of the pelt burden was calculated to be ingested following whole body exposures.