The Lobar Deposition of Little Cigar Smoke Particles in Sprague-Dawley Rat Lungs

KAISEN LIN, Christopher Wallis, Emily Wong, Patricia Edwards, Laura Van Winkle, Anthony S. Wexler, University of California, Davis

     Abstract Number: 426
     Working Group: Health-Related Aerosols

Abstract
Quantifying the dose of tobacco smoke and the location of this dose in the respiratory system is important in understanding its toxicity, addiction, and health effects. Human epidemiology studies have reported that lung tumor incidences varied in different lung regions, i.e., there are more lung tumors in the distal airway than central airway. One hypothesis is that smoke particles deposit heterogeneously in lung airways, which leads to more adverse health effects in certain lung regions. However, not many studies have investigated the pulmonary spatial distribution of inhaled particles from tobacco smoke. Even fewer have explored the particle size distribution of smoke from little cigars, the total dose, and the lobar deposition of particles. Given the increasing popularity of little cigars, especially in young populations, there is an urgent need to conduct research and collect data on this topic. In our study, we explored the lobar deposition of particles from combusted Swisher Sweets regular and menthol-flavored little cigars in rat lungs. We exposed 12-week old male and female Sprague-Dawley to particles at a mass concentration of 80 mg/m3 for 2 hours. Rats were sacrificed immediately after the exposure and lungs were separated to collect individual lobes. The lobe-by-lobe deposition of little cigar smoke particles was calculated based on the deposition of trace metals, which serve as markers of smoke particles and were quantified with inductively coupled plasma mass spectrometry. Trace metal levels were also determined on Day 0, 1, 7, and 28 post-exposure to investigate particle clearance and help understand the long-term health effect of little cigar smoking.