Summary
Characterization of e-cig emissions found bi-modal peaks at approx. 200 nm to 1 um was observed. E-cig emission was comprised of 10^6 - 10^7 particles/cm^2 for all scenarios except for FTC. Overall 50% more particles were generated from tobacco flavor e-liquid, compared to fruit flavor e-liquids. The Modified Puffing Protocol generated six times more particles than the Federal Trade Commission protocol. 5.7 V condition produced higher nicotine concentration, compared to the 3.7 V condition Amounts of ROS varied between 1.2 and 8.9 nmol H2O2eq./puff. H2O2 levels accounted for 12-68% of the total ROS and varied between 0.2 and 6.1 nmol/puff. As the operational voltage increased from the 3.7 V to 5.7, there was an 8x increase in ROS concentration and an increase in H2O2 amount with its relative percentage of the total ROS increasing from 46 to 68%. The 3.7 V sample showed 40% more generation of hydroxyl radicals, compared to the 5.7 V sample when H2O2 was not added. There was no cellular toxicity associated with any test dose. An increase in cellular proliferation resulting from higher doses of 0.075 and 0.1 puffs/mL of the 3.7 V was observed, compared to control. An increase in ROS production resulted from 0.05 and 0.1 puffs/mL, relative to control. 5.7 V also produced significantly more ROS than 3.7 V at both 0.05 and 0.1 puffs/mL concentrations.
Author Conclusions
Characterization of ROS in e-cig emissions indicate that ROS is generated from e-cig exposure. The brand of e-cig, e-liquid flavor, puffing protocol, and operational voltage are contributing factors in the generation of total ROS, H2O2, free radicals, and particle concentration.
Citation
Zhao, J., et al. 2018. Assessment of reactive oxygen species generated by electronic cigarettes using acellular and cellular approaches. Journal of hazardous materials 344: 549-557.
