E-Cigarettes are marketed as a healthier alternative to smoking tobacco and have gained popularity, especially among young people. However, the aerosol that is produced during vaping can contain harmful compounds, such as heavy metals, ultrafine particles, and carcinogenic aldehydes.

Studies performed so far claimed that propylene glycol and glycerin in e-cigarette liquids (e-liquids) are the main source of harmful aldehydes. However, the liquids also contain large amounts of flavorings, whose contribution to aldehyde production upon thermal decomposition had not been studied.

Andrey Khlystov and Vera Samburova, Desert Research Institute, Reno, NV, USA, have measured the amount of twelve different toxic aldehydes produced by flavored and unflavored e-liquids. The team used three popular brands of e-cigarettes and simulated vaping conditions by drawing vapor samples in “puffs” of four seconds each. The samples were analyzed using high-performance liquid chromatography (HPLC).

The researchers found aldehydes in the vapor which were not present in the e-liquids, e.g., formaldehyde and acrolein. Thus, they were produced by thermal decomposition during vaping. While the unflavored liquids produced some toxic aldehydes, the flavored vapor samples contained significantly larger amounts of them. This demonstrates that flavorings are the main source of these harmful compounds. The results also indicate that the aldehyde emissions depend exponentially on the concentration of flavoring compounds. According to the team, further thorough studies of the contributions of flavoring additives to the formation of toxic compounds in e-cigarette vapor are needed.

• Flavoring Compounds Dominate Toxic Aldehyde Production during E-Cigarette Vaping,
  Andrey Khlystov, Vera Samburova,
  Environ. Sci. Technol. 2016.
  DOI: 10.1021/acs.est.6b05145

Also of Interest

• Clever Picture: Nicotine – Chemistry of Smoking,
  ChemViews Mag. 2016.
  DOI: 10.1002/chemv.201600038
  Why do we smoke nicotine and do not inject it?
• Going Up in Smoke,
  Anne Deveson,
  ChemViews Mag. 2016.
  New method for analyzing the composition of electronic cigarette vapors