MedicalResearch: What is the background for this study? What are the main findings?
Dr. Thornburg: RTI wants to improve the human condition by protecting public health from exposure to contaminants. That includes secondhand exposure to electronic cigarette vapors. RTI realized that most research has focused on the electronic cigarette user, not on secondhand exposure. Our research created a simulated lung in our laboratory to produce representative electronic cigarette aerosol that a user would exhale so we could measure the aerosol size distribution and chemical composition. Those two parameters are critical characteristics for understanding the physical and chemical properties of the aerosol as it disperses in the environment to produce the airborne concentrations that determine someone’s secondhand exposure. Our main findings were:
- The aerosol particles exhaled by a user are smaller than 1000 nm, with median size between 100 and 200 nm. The aerosol size distribution varies with the type of e-liquid used.
- The aerosol is made of water, glycerin/propylene glycol, nicotine, artificial flavors, and preservatives
- Artificial flavors identified were ethyl maltol, 2-methyl naphthalene and 2-tert-butyl-p-cresol present.
- BHA and BHT preservatives were present.
- Dosimetry modeling determined that more than 50% of the electronic cigarette emissions were exhaled by the user, potentially leading to secondhand exposure.