Effect of electronic cigarettes on human middle ear

Int J Pediatr Otorhinolaryngol. 2018 Jun;109:67-71. doi: 10.1016/j.ijporl.2018.03.028. Epub 2018 Mar 28.


Objective: Electronic cigarettes (e-cigarettes) are the most commonly used electronic nicotine delivery systems and are a relatively new product designed for smoking cessation. The market scale of electronic cigarettes is growing rapidly, but the potential impact of e-cigarettes on public health has not yet been verified. In this study, we examined the effect of e-liquids on a human middle ear epithelial cell (HMEEC) line.

Material and methods: The main components of e-liquids are propylene glycol, vegetable glycerin and flavoring agents with or without nicotine. We analyzed 73 bottles of e-liquids from 12 different manufacturers, evaluated the trace elements in e-liquids, and identified the cytotoxicity of e-liquids on HMEECs in the presence or absence of nicotine.

Results: In the trace elements analysis, nickel, arsenic, cadmium, and lead were detected in the e-liquids. E-liquids without nicotine decreased cell viability, and the average IC 50 value of total e-liquids (n = 73) was 2.48 ± 0.93%. Among the different flavors, menthol-flavored e-liquids significantly reduced cell viability, and their average IC 50 value (n = 28) was 1.85 ± 0.80%. The average IC 50 values were distinct among manufacturers and the proportion of the solvents.

Conclusion: The present study provides evidence that e-cigarettes influence and reduce human middle ear cell viability even without the application of nicotine. Additionally, the cytotoxicity of e-liquids was affected by the flavoring agents.

Keywords: Cytotoxicity; Electronic cigarette; Heavy metals; Human middle ear epithelial cells; Otitis media.

MeSH terms

  • Arsenic / toxicity
  • Cadmium / toxicity
  • Cell Line
  • Cell Survival / drug effects*
  • Ear, Middle / cytology*
  • Electronic Nicotine Delivery Systems*
  • Epithelial Cells / physiology*
  • Flavoring Agents / toxicity*
  • Glycerol / toxicity
  • Humans
  • Inhibitory Concentration 50
  • Lead / toxicity
  • Menthol / toxicity
  • Nickel / toxicity
  • Nicotine / toxicity*


  • Flavoring Agents
  • Cadmium
  • Menthol
  • Lead
  • Nicotine
  • Nickel
  • Arsenic
  • Glycerol