Global vs. Local Dose Deliveries of Airborne Particles through Dosimetric Aerosol in Vitro Inhalation Device (DAVID)

SRIPRIYA NANNU SHANKAR, Amber O'Connor, Eric Le, Kiran Mital, Alex Theodore, Tara Sabo-Attwood, Gregory S. Lewis, Arantzazu Eiguren-Fernandez, Chang-Yu Wu, University of Florida

     Abstract Number: 623
     Working Group: Aerosol Exposure

Abstract
Aerosol particle deposition in human respiratory system depends on particle characteristics and the respiratory mechanics of an individual. Based on the deposition pattern of particles in the respiratory tract, local and global doses can vary which thus affect the health effects. It is hence critical for in vitro exposure systems to represent different patterns of particle deposition while assessing the impact of airborne particles. In this study, the collection unit of Dosimetric Aerosol in Vitro Inhalation Device (DAVID) was modified to facilitate annular deposition of airborne particles onto A549 cells cultured at air-liquid interface (ALI) by rotating the collector wells using an external worm gear motor, in addition to focused spot deposition. Copper oxide (CuO) nanoparticles suspended in ethanol (0.1, 0.5, 1 and 10 mg/mL) were used to generate aerosols using a Collison nebulizer (5 LPM). The aerosols were then diluted with 15 LPM of compressed air and collected by DAVID at 4 LPM, for 15 min. Analysis of the delivered particles by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) following acid digestion revealed global doses ranging from 27±2 to 467±27 µg/cm², while the local doses ranged between 99±6 and 2814±163 µg/cm². Statistical analysis of global doses by ANOVA showed there was neither a significant difference between deposition patterns nor between replicate wells, for nebulizer suspensions of 0.1-1 mg/mL. However, the spot deposition resulted in a dose ~1.6 times of the annular deposition for 10 mg/mL. In comparison, there was a significant difference between patterns and replicate wells for local doses with nebulizer suspensions 0.1-10 mg/mL. The ratio of local dose delivered as spots was ~1.7 times of annular deposition for 0.1-1 mg/mL, while it increased to ~2.6 times for 10 mg/mL. The study highlights the importance of global and local doses in dosimetry, and the need for assessing cellular response with respect to the same.