Influence of particle size on early distribution and retention patterns for inhaled, relatively insoluble particles

Fischer-344 rats (12 to 14 weeks old) were exposed nose-only to one of three monodisperse fused aluminosilicate aerosols labeled with 134Cs; thirty rats were exposed to 0.67-μm-AD particles, 40 rats to 1.38-μm-AD particles and 30 rats to 2.79-μm-AD particles. Each group had an equal number of males and females and was whole-body counted and members were sacrificed at 2 hours, 2, 7, 14 and 28 days after exposure. Results indicated different deposition patterns for these three particle sizes, with 16.3 to 35.0% of the initial body burden being deposited in the deep lung. As expected, early deposition included a substantial degree of upper respiratory tract burden as well as contamination of skin around the nose