It should be noted that the American context is not the same as that of France, or even of Europe. In Europe, the TPD (Tobacco Product Directive) restricts nicotine in e-liquids to 20 mg/mL, which is not the case in the USA where e-liquids can be found with more than 50 mg/mL, levels that would be liable to strongly increase dependency. Also, the advertising campaigns of e-liquid manufacturers, legal in the USA, directly target young people. JUUL is a prime example. By directing its advertising towards adolescents, sales of its e-cigarettes to minors have exploded, starting the current controversy in the USA.

The regulation of flavourings

For some months, the FDA (Food and Drug Administration) which in the USA controls the marketing of vaping products, is threatening to reduce the sale of flavoured e-liquids. Since last summer, in San Francisco, shops can only sell tobacco flavour e-liquids and currently the State of New York talks about boycotting. These prohibitions would be based on findings related to an alarming increase of young people trying electronic cigarettes in the USA.

Even if it is found that vaping products are much less harmful and noxious than tobacco cigarettes, the nicotine possibly present in electronic devices remains a potentially addictive substance. Moreover, research concludes that young people who vape have 3 to 4 times greater risk of then passing on to tobacco cigarettes: The famous gateway theory. However, this study1 carried out by the Center for Tobacco Control Research and Education of the University of California was directed by Pr Stanton Glantz, an unconditional critic of electronic cigarettes.

Currently data on the gateway effect of the electronic cigarette remains fuzzy. According to an independent study of 2017, there is no proof that e-cigarettes can push an adolescent to consume tobacco2. On the contrary many publications show a link between the reduction of smoking among young people and the appearance of the electronic cigarette2,3.

According to these researchers, vaping could on the contrary have a role of diversion from tobacco.

Sugar: the fashionable taste

Recent publications show that regular vapers have a clear preference for sweetened flavourings4,5. A study by Dr K. Farsalinos et al, carried out in the form of an online survey (with more than 4000 users) showed that the variety of flavourings constituted a significant factor in the efficiency of smoking cessation6. In 2018, Russell et al confirm these results with a study carried out on 20,836 users of electronic cigarettes in the USA. They conclude that restricting the availability of tobacco-free flavourings could reduce smokers’ interest in going to e-cigarettes or encourage their return to tobacco cigarettes7.

The study of flavourings: a huge labour

Today flavourings are widely studied for their capacity to induce toxicity by inhalation8,9.

Flavourings used in e-liquids are most often developed to be ingested but not inhaled. The metabolism induced then is different and certain molecules they contain can turn out to be toxic for respiratory routes10. Moreover, when heated by the e-cigarette, the nature of the flavourings is liable to be modified which can cause the release of degradation products that are potentially toxic.

Account has to be taken of the risks of synergy and interaction between aromatic molecules, which, alone, may be inoffensive but toxic when mixed…

The flavourings have to be analysed and the presence of molecules recognized for causing respiratory troubles limited. However, this is a huge task, and few manufacturers have the capacity to carry out such research, which is time-consuming and very costly.

Towards regulations?

Currently in the USA, no law governs the composition of e-liquids, and manufacturers alone are responsible for the type of flavouring and the amount present in e-liquids.

In France and Europe, some standards, with voluntary application, propose a list of molecules to be limited or banned (diacetyl, sugars, sweeteners…) but only a few manufacturers comply with them. The British Standards Institution (BSI) and the AFNOR (Association française de normalisation) published respectively PAS 54115:2015 and XP D90–300–2. These two voluntary standards describe, among other things, manufacturing conditions, quality control of the raw materials used, and traceability in process.

A European standard (with compulsory application) is currently being drafted at CEN (European Committee for Standardization), in continuation of the work started with the French standard.

Regulations should not harm smoking cessation

The real debate here concerns the balance between the potential risk run by the consumer with flavouring inhalation and the real risk represented by tobacco cigarettes. What is certain is that a significant number of vapers risk returning to tobacco cigarettes if they no longer enjoy vaping.

Also, different measures can be taken to control the composition of e-liquids, while allowing them considerable diversity:

  • Improving control of prohibited sales to minors,
  • Carrying out in-depth studies on flavourings,
  • Imposing a quality charter for the manufacture of e-liquids,
  • Banning or limiting certain molecules known for their irritant or toxic effects…

Electronic cigarettes are efficient tools for smoking cessation because linked to the taste pleasure of the flavourings and their wide choice, capable of satisfying a large majority of consumers. Prohibiting the addition of flavourings to e-liquids would close the door to many smokers, addicted to tobacco.

In this context, world experts have written a letter to the FDA so that its directives do not have “possible harmful effects on public health that could stem from an over-reaction”11.


  1. Watkins, S. L., Glantz, S. A. & Chaffee, B. W. Association of Noncigarette Tobacco Product Use With Future Cigarette Smoking Among Youth in the Population Assessment of Tobacco and Health (PATH) Study, 2013-2015. JAMA Pediatr. 172, 181 (2018).
  2. O’leary, R., Macdonald, M., Stockwell, T. & Reist, D. Clearing the Air: A systematic review on the harms and benefits of e-cigarettes and vapour devices. (2017).
  3. Levy, D. T. et al. Examining the relationship of vaping to smoking initiation among US youth and young adults: a reality check. Tob Control 0, 1–7 (2018).
  4. Zare, S., Nemati, M. & Zheng, Y. A systematic review of consumer preference for e-cigarette attributes: Flavor, nicotine strength, and type. PLoS One 13, e0194145 (2018).
  5. Harrell, M. B. et al. Flavored e-cigarette use: Characterizing youth, young adult, and adult users. Prev. Med. Reports 5, 33–40 (2017).
  6. Farsalinos, K. et al. Impact of Flavour Variability on Electronic Cigarette Use Experience: An Internet Survey. Int. J. Environ. Res. Public Health 10, 7272–7282 (2013).
  7. Russell, C., Mckeganey, N., Dickson, T. & Nides, M. Changing patterns of first e-cigarette flavor used and current flavors used by 20,836 adult frequent e-cigarette users in the USA. doi:10.1186/s12954-018-0238-6
  8. Kaur, G., Muthumalage, T. & Rahman, I. Mechanisms of toxicity and biomarkers of flavoring and flavor enhancing chemicals in emerging tobacco and non-tobacco products. Toxicol. Lett. (2018). doi:
  9. Zhao, J. et al. Assessing electronic cigarette emissions: linking physico-chemical properties to product brand, e- liquid flavoring additives, operational voltage and user puffing patterns Assessing electronic cigarette emissions: linking physico-chemical properties to product brand, e-liquid flavoring additives, operational voltage and user puffing patterns. Inhal. Toxicol. 30, 78–88 (2018).
  10. Bitzer, Z. T. et al. Effect of flavoring chemicals on free radical formation in electronic cigarette aerosols. Free Radic. Biol. Med. 120, 72–79 (2018).
  11. Miller, T. J. et al. Youth vaping and the dangers of over-reaction – a letter to the FDA. (2018). Available at: (Accessed: 28th November 2018)