AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Tobacco Smoke Dose at the Air-Liquid Interface In Vitro
Jason Adamson, JOHN MCAUGHEY, British American Tobacco
Abstract Number: 263 Working Group: Health Related Aerosols
Abstract Tobacco smoke is a complex dynamic aerosol. It is a self-selected source of particle inhalation and exposure, despite its documented adverse health effects. It is important to fully characterise absolute particle dose in vivo and in vitro, and to consider dose in terms of particle number, surface area or mass. This approach offers insight into the relationship between dose and subsequent biological effect.
Tobacco smoke exposures (30 minutes) using a Borgwaldt RM20S smoking engine ranging from 0.22–25.75 micrograms per cm$^2 for smoke dilutions from 1:400 to 1:5 respectively were measured using a quartz crystal microbalance in a well-based air-liquid interface (ALI) exposure system. Smoke particle diameter by electrical mobility(Cambustion DMS-500, UK) gives a volume-weighted median diameter of 394 nm at 1:60 dilution. Assuming a confluent monolayer of A549 lung epithelial cells of notional 18 micrometer diameter at the ALI, this represents an approximate cell density of 3.93e5 cells per cm$^2. Assuming a log-normal distribution and a smoke particle density of 1120 kg per m$^3, a 394 nm diameter particle will weigh 35.8 fg. Thus, the measured mass depositions of 0.22–25.75 micrograms per cm$^2 for the smoke are equivalent to particle number exposures of 6.14e6-7.18e8 per cm$^2 and particle surface area exposures of 7.5e-3-8.8e-1 cm$^2 per cm$^2 lung surface area. In practice, this suggests each A549 cell is exposed to 16-1830 smoke particles over the measured dilution range. These surface area doses are similar to reported pro-inflammatory threshold values of 1-10 cm$^2 particle surface area per cm$^2 cell surface area.
The precision and accuracy of the smoke measurement methods and the resulting absolute metrics will be compared with daily in vivo dose estimates and measurements in the airways of smokers.