Potential Respiratory Health Effects of Electronic Cigarette Emissions

摘要

The emerging trend of electronic cigarettes (e-cig) poses several new issues for regulatory agencies due to limited data characterizing e-cig emissions and toxicity. To help understand potential health effects, we conducted a study to characterize the inhalation dosimetry and cytotoxicity of e-cig emissions. Mainstream e-cig emissions were generated using a commercially available e-cig and two types of liquid (liquid-1 and 2). We simulated smoking events using behavioral pattern data and smoke inhalation parameters, reported for conventional cigarette. Aerosol deposition fractions in the lungs of a 14-year old adolescent and exhalation fraction were calculated using Multiple-Path Particle Dosimetry model with the measured aerosol size and concentration as model inputs. Mainstream emissions of each e-cig liquid and conventional cigarette were separately collected in cell culture media using liquid impingers. Human airway cells (NL20) were inoculated with the culture media at the doses equivalent to smoking 1 and 3 cigarettes, and cytotoxicity was measured by lactate dehydrogenase (LDH) assays after 24 hours. We also inoculated cell cultures with the neat liquids and measured cell viability by trypan blue staining. The dosimetry model indicated that 47% of mass of inhaled emission were deposited in the lung, with 40% in the alveolar region, and 53% was exhaled. Liquid-1 induced a higher LDH activity than conventional cigarettes, and both caused much greater response than liquid-2 and controls. Cells inoculated with the different neat liquids showed similar toxicity between those in a dose-dependent manner. This study showed differential cytotoxicity caused by inhalation exposures to different types and doses of e-cig emissions. There is also a potential concern for second-hand exposure. Understanding the physical, chemical, and toxicological properties of myriad products will require standardized testing approaches so that reliable comparisons can be made.