Influence of the E-Cigarette Emission Profile by the Ratio of Glycerol to Propylene Glycol in E-Liquid Composition.

Introduction:
This text discusses a study on the emission profiles of electronic cigarettes (E-cig) based on the ratio of glycerol to propylene glycol in E-liquids and the effects of menthol flavoring. The study aims to provide a better understanding of E-cig emission characteristics for many commercially available E-liquid products.

Key Points:

* The study used impurity-free E-liquids containing only propylene glycol and glycerol in various percentage ratios along with two commercially available E-liquids.
* The vapor phases of E-cig emissions were analyzed using gas chromatography-mass spectrometry (GC-MS) to elucidate the transformation pathways of the major emitted compounds without the confounding effects of existing impurities or flavor ingredients added to E-liquids.
* The analysis detected toxicants such as acetaldehyde, acrolein, benzaldehyde, as well as benzene, toluene, ethylbenzene, and xylene (BTEX) compounds.
* The concentration of these hazardous compounds emitted increased with increasing glycerol percentage in the E-liquid.
* Benzaldehyde, naphthalene, diphenyl ether, and glycerol along with menthol and nicotine that were present in the commercial E-liquids were also detected in the aerosol condensates.
* The cascade impactor data on the distribution of nicotine and menthol in different size fractions from >2.5 to <2.5 μm allow the estimates of the extent of toxicant deposition in different parts of the pulmonary system including the oropharynx region, the trachea as well as inside the alveoli and bronchioles.
* The study shows that E-liquids containing higher percentages of glycerol will produce higher levels of toxicants compared to E-liquids with similar percentages of propylene glycol.

Main Message:
The study highlights that users of E-cig are exposed to harmful chemicals even if the E-liquids contain only propylene glycol and glycerol without flavorings, nicotine, or impurities. Furthermore, E-liquids with higher percentages of glycerol will produce higher levels of toxicants, which has important implications for E-cigarette vendors, manufacturers, consumers, and regulatory agencies. The study emphasizes the need for further research on the health effects of E-cigarette use and stricter regulations on E-liquid composition and emissions.

Ooi BG, Dutta D, Kazipeta K, Chong NS. Influence of the E-Cigarette Emission Profile by the Ratio of Glycerol to Propylene Glycol in E-Liquid Composition. aCS omega. 2019;4(8):13338-13348. doi:10.1021/acsomega.9b01504