Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Randomized Controlled Trial
. 2020 Apr 21;22(5):791-797.
doi: 10.1093/ntr/ntz130.

The Impact of E-liquid Propylene Glycol and Vegetable Glycerin Ratio on Ratings of Subjective Effects, Reinforcement Value, and Use in Current Smokers

Tracy T Smith  1   2 , Bryan W Heckman  1   2 , Amy E Wahlquist  2   3 , K Michael Cummings  1   2   3 , Matthew J Carpenter  1   2   3
Affiliations
Randomized Controlled Trial

The Impact of E-liquid Propylene Glycol and Vegetable Glycerin Ratio on Ratings of Subjective Effects, Reinforcement Value, and Use in Current Smokers

Tracy T Smith et al. Nicotine Tob Res. .

Abstract

Introduction: Electronic nicotine delivery systems (ENDS) vary on a wide range of characteristics that may affect reinforcement value and use. One characteristic is the ratio of two solvents commonly used in most e-liquids: propylene glycol (PG) and vegetable glycerin (VG). The goal of this study was to understand how PG/VG ratio affects subjective effects, reinforcement value, and tobacco use patterns among current smokers who try using ENDS.

Aims and methods: Current smokers with minimal ENDS use history (n = 30) sampled, in a double-blind fashion, three different e-liquids that varied in PG/VG ratio (70/30, 50/50, 0/100) while holding constant other aspects of the e-liquid and ENDS. Participants tried each e-liquid before rating the subjective effects on a modified version of the Cigarette Evaluation Questionnaire. Reinforcement value was assessed using a preference task where participants chose between the three e-liquids. The impact of each e-liquid on cigarette reinforcement was assessed using a modified version of the Cigarette Purchase Task. Participants were randomly assigned to receive one e-liquid to take home for 1 week.

Results: PG/VG ratio had minimal impact on most of the tested outcomes. Participants rated the highest PG concentration as having a stronger "throat hit" than the other two. There was no significant difference between the number of participants who preferred each of the PG/VG ratios in the preference assessment. PG/VG ratio did not affect cigarette or ENDS use during the sampling week.

Conclusions: These data suggest that PG/VG ratio has minimal impact on subjective effects and reinforcement value in ENDS naive current smokers.

Implications: These data suggest that PG/VG ratio, within the range that is commonly used, has minimal impact on subjective effects, reinforcement value, or uptake in current smokers with minimal ENDS experience.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
The impact of product and propylene glycol (PG)/vegetable glycerin (VG) ratio on subjective effects. Average product ratings on five subscales, throat hit, and vapor production after sampling each product. Significant pairwise difference from usual brand indicated by “*”. Significant difference from two other PG/VG ratios indicated by “+”.
Figure 2.
Figure 2.
Impact of propylene glycol (PG)/vegetable glycerin (VG) ratio on e-liquid preference. Number of participants preferring each of the available options during preference task when excluding (A) and including (B) the option to abstain. Ties are excluded (A = 4; B = 6).
Figure 3.
Figure 3.
The impact of e-liquid sampling and propylene glycol (PG)/vegetable glycerin (VG) ratio on cigarette smoking behavior. Average cigarettes smoked per day in each of the PG/VG ratio e-liquid groups during baseline naturalistic week (Days 1–8) and electronic nicotine delivery system (ENDS) sampling (Days 9–15). For participants who had more than 8 days included in baseline or 7 days included in the sampling week, additional days are not shown. Participants received the ENDS during their sampling visit on Day 9.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Hu SS, Neff L, Agaku IT, et al. . Tobacco product use among adults – United States, 2013-2014. MMWR Morb Mortal Wkly Rep. 2016;65(27):685–691. - PubMed
    1. Action on Smoking or Health (ASH). Use of e-cigarettes (vapourisers) among adults in Great Britain, 2018; https://ash.org.uk/download/ash-use-of-e-cigarettes-by-adults-in-great-b.... Accessed August 21, 2019.
    1. Coleman B, Rostron B, Johnson SE, et al. . Transitions in electronic cigarette use among adults in the Population Assessment of Tobacco and Health (PATH) Study, Waves 1 and 2 (2013–2015). Tob Control. 2018;(1):50–59. - PMC - PubMed
    1. DeVito EE, Krishnan-Sarin S. E-cigarettes: impact of e-liquid components and device characteristics on nicotine exposure. Curr Neuropharmacol. 2018;16(4):438–459. - PMC - PubMed
    1. Wagener TL, Floyd EL, Stepanov I, et al. . Have combustible cigarettes met their match? The nicotine delivery profiles and harmful constituent exposures of second-generation and third-generation electronic cigarette users. Tob Control. 2017;26(e1):e23–e28. - PMC - PubMed

Publication types