E-Liquid Flavours


Comparison of the Cytotoxic Potential of Cigarette Smoke and Electronic Cigarette Vapour Extract on Cultured Myocardial Cells

Konstantinos E. Farsalinos, Giorgio Romagna, Elena Allifranchini, Emiliano Ripamonti, Elena Bocchietto, Stefano Todeschi, Dimitris Tsiapras, Stamatis Kyrzopoulos, Vassilis Voudris

Smoking is an important risk factor for cardiovascular disease and cigarette smoke (CS) has well-established cytotoxic effects on myocardial cells. The purpose of this study was to evaluate the cytotoxic potential of the vapour of 20 EC (e-cigarette)  liquid samples and a “base” liquid sample (50% glycerol and 50% propylene glycol, with no nicotine or flavourings) on cultured myocardial cells. Included were 4 samples produced by using cured tobacco leaves in order to extract the tobacco flavour. Methods: Cytotoxicity was tested according to the ISO 10993-5 standard.

In conclusion, from 20 commercially-available EC liquids that were tested in vapour form, four were found to be cytotoxic on cultured cardiomyoblasts. Cytotoxicity was mainly observed in most (but not all) samples produced by using tobacco leaves, while one sample using food-approved flavouring was marginally cytotoxic. EC vapour production by using higher-voltage devices caused a decrease in cell survival. Overall, EC vapour extracts showed significantly higher cell viability compared to CS extract, based on a realistic-use rather than a standardized comparative level of exposure. This supports the concept that ECs may be useful as tobacco harm reduction products

Impact of Flavour Variability on Electronic Cigarette Use Experience: An Internet Survey

Konstantinos E. Farsalinos, Giorgio Romagna, Dimitris Tsiapras, Stamatis Kyrzopoulos, Alketa Spyrou, Vassilis Voudris

4,618 participants were included in the analysis, with 4,515 reporting current smoking status (current vs. former smokers).

More than 90% were former smokers. The mean age was 40 years

At the time of participation, most commonly used flavours were fruits, followed by sweets. 

Most participants (68.3%) were switching between flavours on a daily basis or within the day, with former smokers switching more frequently. More than half of the study sample mentioned that they like the variety of flavours and that the taste gets blunt from long-term use of the same flavour. The average score for importance of flavours variability in reducing or quitting smoking was 4 (“very important”). Finally, the majority of participants stated that restricting variability of flavours would make the EC experience less enjoyable while almost half of them answered that it would increase craving for tobacco cigarettes and would make reducing or completely substituting smoking less likely.

The results of this survey indicate that EC liquid flavourings play a major role in the overall experience of dedicated users and support the hypothesis that they are important contributors in reducing or eliminating smoking consumption.


An approach to ingredient screening and toxicological risk assessment of flavours in e-liquids

S.Costigan, C.Meredith
Published online: Jul 2015

“Individual flavours or groups of flavours were added to the tobacco rod and the resultant smoke was analysed for priority smoke constituents and tested in several in vitro tests as well as 90-day rat inhalation studies. In general, addition of the flavours had no effect on, or reduced the levels of most of the measured smoke constituents.”

The Impact of Flavor Descriptors on Nonsmoking Teens’ and Adult Smokers’ Interest in Electronic Cigarettes

Saul Shiffman, Mark A Sembower, Janine L Pillitteri, Karen K Gerlach, Joseph G Gitchell
Published online: 07 Jan 2015

Non-smoking teens’ interest in e-cigarettes was very low. Adult smokers’ interest was significantly higher overall and for each flavour. 

Teen interest did not vary by flavour, but adult interest did.

Past-30-day adult e-cigarette users had the greatest interest in e-cigarettes, and their interest was most affected by flavour. 

Non-smoking teens who had never tried e-cigarettes had the lowest interest, followed by adults who had never tried e-cigarettes

Preferred Flavors and Reasons for E-cigarette Use and Discontinued Use Among Never, Current, and Former Smokers

Carla J Berg
Published online: 18 Nov 2015

Never users had significantly lower prevalence of use of alcohol, marijuana, and other tobacco products (take less risks)

Among current e-cigarette users, the most commonly used flavour was fruit flavours (67%)

The most commonly reported reasons for e-cigarette use were “they might be less harmful than cigarettes” (77%); “they don’t smell” (77%); “they help people quit smoking” (66%); and “they cost less than other forms of tobacco” (62%); these reasons were more frequently endorsed by former smokers.

Over 90% of former cigarette smokers who were current e-cigarette users reported using e-cigarettes to quit smoking.

Over half of never smokers who are former e-cigarette users said they did not recently use e-cigarettes because they “just don’t think about it”, possibly indicating that addiction did not play a role in their use


Cigarette smoking and electronic cigarette vaping patterns as a function of e-cigarette flavourings

Mark D Litt, Valerie Duffy, Cheryl Oncken
Published online: 15 Sep 2016

The findings suggest that adoption of e-cigarettes in smokers may influence smoking rates of people who smoke.

E-cigarette vaping rates are influenced by flavourings.

These findings may have implications for the utility of e-cigarettes as a nicotine replacement device and for the regulation of flavourings in e-cigarettes for harm reduction.


Do flavouring compounds contribute to aldehyde emissions in e-cigarettes?

Konstantinos E. Farsalinos, VassilisVoudris
Published online: May 2018

Aldehyde emissions from all flavoured liquids were 79–99.8% lower than smoking and lower than commonly measured indoor levels and occupational and indoor safety limits.

Patterns of flavored e-cigarette use among adults vapers in the United States: an internet survey

Konstantinos Farsalinos, Christopher Russell, George Lagoumintzis, Konstantinos Poulas
Published online: 21 Mar 2018

In conclusion, this cross-sectional study of a very large sample of adult US e-cigarette users, most of which were former smokers, identified the importance of non-tobacco flavours in e-cigarette use initiation and sustained use, and their contribution to smoking cessation and relapse prevention. This information should be considered by regulators in order to avoid unintentional adverse effects of over-restrictive regulation on e-cigarette flavours.

Changing patterns of first e-cigarette flavor used and current flavors used by 20,836 adult frequent e-cigarette users in the USA

Christopher Russell, Neil McKeganey, Tiffany Dickson, Mitchell Nides
Published online: 28 Jun 2018

Conclusion: Adult frequent e-cigarette users in the USA who have completely switched from smoking cigarettes to using e-cigarettes are increasingly likely to have initiated e-cigarette use with non-tobacco flavours and to have transitioned from tobacco to non-tobacco flavours over time. Restricting access to non-tobacco e-cigarette flavours may discourage smokers from attempting to switch to e-cigarettes.

Should flavours be banned in cigarettes and e-cigarettes? Evidence on adult smokers and recent quitters from a discrete choice experiment

John Buckell, Joachim Marti, Jody L Sindelar
Published online: 28 May 2018

A ban on flavoured e-cigarettes alone would likely increase the choice of cigarettes in smokers, arguably the more harmful way of obtaining nicotine


Effects of flavoring compounds used in electronic cigarette refill liquids on endothelial and vascular function

Gerald Wölkart, Alexander Kollau, Heike Stessel, Michael Russwurm, Doris Koesling, Astrid Schrammel, Kurt Schmidt, Bernd Mayer
Published online: 9 Sep 2019

Conclusion: Our data indicate that flavourings typically present in e-cig refill liquids do not cause endothelial dysfunction that would result in impaired vasodilation upon acute exposure. In contrast, most of the tested compounds caused endothelium-independent vasorelaxation, albeit at fairly high concentrations that appear to exceed by far the plasma concentrations expected to occur upon vaping flavoured liquids.

Toxicity classification of e-cigarette flavouring compounds based on European Union regulation: analysis of findings from a recent study

Konstantinos Farsalinos, George Lagoumintzis
Published online: 25 Jul 2019

The vast majority of flavouring compounds in e-cigarette liquids as reported in a recent study were present at levels far lower than needed to classify them as toxic. 

High Content Screening in NHBE cells shows significantly reduced biological activity of flavoured e-liquids, when compared to cigarette smoke condensate

Lukasz Czekala, Liam Simms, Matthew Stevenson, EdgarTrelles-Sticken, Paul Walker, Tanvir Walele
Published online: Aug 2019

Our results clearly show a lower toxicity of e-liquids, including flavoured e-liquids, when compared to CSC (cigarette smoke condensate). Typically, more than 100 times higher concentrations of CFs (Base liquids, with or without nicotine, and commercial, flavoured, nicotine-containing e-liquids) are required to elicit the same response as those observed for 3R4F CSC in specific endpoints.

Flavours play a critical role in attracting, and retaining smokers to e-cigarettes.

Changes in Flavor Preference in a Cohort of Long-Term Electronic Cigarette Users

Ping Du, Rebecca Bascom, Tongyao Fan, Ankita Sinharoy, Jessica Yingst, Pritish Mondal, Jonathan Foulds
Published online: 21 Jun 2019

Using a nontobacco flavour they liked made former smokers less likely to return to cigarette smoking.

Our results regarding anticipated reactions to FDA e-cigarette flavour regulation suggest complexities such that the benefits and risks of flavour ban need to be carefully evaluated.

However, a majority anticipated that they would personally attempt to circumvent potential FDA regulations of e-cigarettes by obtaining e-cigarette flavours from various illicit sources (e.g., Internet orders from foreign countries) or even self-making flavours.

The use of flavouring agents purchased from unregulated sources could lead to additional unanticipated toxicities.

It is also concerning that some established e-cigarette users believed that they would return to cigarette smoking if nontobacco e-cigarette flavours were banned. Thus, for adult e-cigarette users who use certain flavours to facilitate smoking cessation or reduction, banning all nontobacco flavours could precipitate relapse to smoking.

The role of flavors in vaping initiation and satisfaction among U.S. adults

Robyn L. Landry, Allison L. Groom, Thanh-Huyen T. Vu, Andrew C. Stokes, Kaitlyn M. Berry, Anshula Kesh, Joy L. Hart, Kandi L. Walker, Aida L. Giachello, Clara G. Sears, Kathleen L. McGlasson, Lindsay K. Tompkins, Delvon T. Mattingly, Rose Marie Robertson, Thomas J. Payne
Published online: Dec 2019

In terms of cigarette smoking status, 35.6% of respondents were past smokers, and 38.0% were current smokers. 

Most common reasons for vaping initiation were as an alternative to cigarettes (43.7%) and because respondents viewed e-cigarettes as less harmful than other tobacco products (31.2%). Flavour was the third most commonly reported reason.

Satisfaction among those who bought flavoured e-liquid was higher than those who did not buy flavoured e-liquid.


Intended and Unintended Effects of Banning Menthol Cigarettes

Christopher Carpenter, Hai V. Nguyen
Published online: Feb 2020

Menthol bans significantly increased non-menthol cigarette smoking among youths, resulting in no overall net change in youth smoking rates.

Menthol bans shifted smokers’ cigarette purchases away from grocery stores and gas stations to First Nations reserves (where the menthol bans do not bind).

Associations of Flavored e-Cigarette Uptake With Subsequent Smoking Initiation and Cessation

Abigail S. Friedman, SiQing Xu
JAMA Network Open
Published online: 5 Jun 2020

Relative to vaping tobacco flavours, vaping nontobacco-flavoured e-cigarettes was not associated with increased youth smoking initiation but was associated with an increase in the odds of adult smoking cessation.

Association of vaping-related lung injuries with rates of e-cigarette and cannabis use across US states

Abigail S. Friedman
Published online: 25 Aug 2020

At the same time, policymakers should proceed with caution when considering bans on flavoured e‐liquids: restricting legal sales may push some vapers towards illicit sources, user‐modified e‐liquids (e.g. to add flavouring) or even conventional cigarette use. Given EVALI’s potential lethality and a myriad of work suggesting that conventional cigarette use is probably far more dangerous than vaping nicotine, these outcomes could be disastrous for public health.

Reported patterns of vaping to support long-term abstinence from smoking: a cross-sectional survey of a convenience sample of vapers

Sarah Victoria Gentry, Emma Ward, Lynne Dawkins, Richard Holland, Caitlin Notley
Published online: 6 Oct 2020

Most attempts at smoking cessation result in relapse, and smokers generally make multiple quit attempts before succeeding. 

Qualitative research suggests e-cigarettes can meet many of the needs of ex-smokers by substituting physical, psychological, social, cultural and identity-related aspects of tobacco addiction. 

According to a time-series analysis of data from the Smoking Toolkit study, in which repeated cross-sectional surveys are conducted with a representative sample of households in England, increasing prevalence of e-cigarette use in current smokers was predictive of higher success rates of quit attempts.

Most participants were self-reported long-term abstinent smokers (86.3%).

Those who start on a low self-reported nicotine e-liquid concentration (strength) will be more likely to relapse to tobacco smoking than those starting on a higher nicotine e-liquid, after controlling for cigarettes per day (CPD) before cessation.

Results suggest a change in flavour choices over the course of vaping initiation and uptake. There was a reduction in the proportion of people using a tobacco flavour, and increase in the proportion using a fruit/sweet/food flavour, from initial to current flavour choice 

According to the 2017 ASH-A survey, among current users, fruit flavours were the most popular.

The impact of a comprehensive tobacco product flavor ban in San Francisco among young adults

Yong Yang, Eric N. Lindblom, Ramzi G. Salloum, Kenneth D. Warda
Published online: Jun 2020

A sample of San Francisco residents aged 18–34 who previously used tobacco products were surveyed about their tobacco use both before and after the ban. 

Among the 18–24 age group, there was a significant increase in cigarette smoking.

Cigarette smoking increased among 25–34 years old.

Banning flavours in e-cigarettes would prompt e-cigarette use cessation but may also push some e-cigarette users to turn to cigarette smoking and could prompt some youth to initiate into smoking instead of e-cigarette use.

The proportions of e-cigarettes, cigarettes, and cigars obtained over the internet increased after the ban, and the proportions obtained from retailers outside of San Francisco also increased overall.