E-cigarette flavors are toxic to white blood cells, warn scientists

E-cigarette flavors health risk

New research adds to growing evidence on the harmful health effects of e-cigarettes. Image: Shutterstock

Cinnamon, vanilla and buttery e-cigarette flavors are among the most toxic — and mixing flavors is more damaging than vaping just one

— By Tanya Petersen

Sugar and spice are not so nice, at least when it comes to vaping or inhalation. Exposure to e-cigarette flavoring chemicals and liquids can cause significant inflammation to monocytes, a type of white blood cell — and many flavoring compounds are also toxic, with cinnamon, vanilla and buttery flavors among the worst. That’s the finding of new research published in open-access journal Frontiers in Physiology, which also found that mixing e-cigarette flavors has a much worse effect than exposure to just one. The study adds to growing evidence on the harmful health effects of e-cigarettes.

The use of e-cigarettes has exploded in the past decade as traditional cigarette consumption has declined. In the United States alone, more than 500 e-cigarette brands with almost 8,000 uniquely flavored e-juices are available to consumers.

Vaping exposes the lungs to flavoring chemicals when the e-liquids are heated and inhaled. Since the flavoring chemicals are considered safe to eat, e-cigarettes are often considered — and advertised — as a healthier alternative to traditional cigarettes. However, the health effects of inhaling these chemicals are not well understood.

This new study, led by researchers at the University of Rochester Medical Centre in the United States, wanted to test the assumption that vaping nicotine-free flavored e-liquids is safer than smoking conventional cigarettes. Previous studies show that flavors used in e-cigarettes cause inflammatory and oxidative stress responses in lung cells. Users of e-cigarettes also show increased levels oxidative stress markers in the blood compared to non-smokers. The new study extends this to assess the effects of commonly used flavoring chemicals, as well as e-liquids without nicotine, directly on immune cells — namely, a type of white blood cell called monocytes.

Exposure to the e-cigarette flavoring chemicals and e-liquids led to higher production of two well-established biomarkers for inflammation and tissue damage mediated by oxidative stress. Furthermore, many of the flavoring chemicals caused significant cell death — with some flavors being more toxic than others.

The study’s first author, Dr Thivanka Muthumalage says that while the flavoring compounds tested may be safe for ingestion, these results show they are not safe for inhalation. “Cinnamon, vanilla and butter flavoring chemicals were the most toxic but our research showed that mixing flavors of e-liquids caused by far the most toxicity to white blood cells.”

Senior author, Dr Irfan Rahman, says he hopes this new data will provide insights into understanding the harmful effects of flavored e-juices without nicotine.

“Currently, these are not regulated, and alluring flavor names, such as candy, cake, cinnamon roll and mystery mix, attract young vapers,” he says. “Our scientific findings show that e-liquid flavors can, and should, be regulated and that e-juice bottles must have a descriptive listing of all ingredients. We urge regulatory agencies to act to protect public health.”

This study directly exposed monocytic blood cells to e-liquids. The authors plan to undertake further research to simulate live vaping, by exposing cells to e-liquid aerosols in an air-liquid interface system. They also call for further long-term human studies to assess the harmful effects of e-cigarettes.

Original research article: Inflammatory and Oxidative Responses Induced by Exposure to Commonly Used e-Cigarette Flavoring Chemicals and Flavored e-Liquids without Nicotine

Corresponding author: Dr. Irfan Rahman

REPUBLISHING GUIDELINES: Open access and sharing research is part of Frontier’s mission. Unless otherwise noted, you can republish articles posted in the Frontiers news blog — as long as you include a link back to the original research. Selling the articles is not allowed.

15 Comments on E-cigarette flavors are toxic to white blood cells, warn scientists

  1. Interesting article. Alway felt these e-cigarettes were no good….


  2. Thanks for writing such an informative article. I have been vaping for months but did not know this thing. Well, from now on I will be careful while choosing the flavors. Thanks once again!


  3. Manuel Mora // March 2, 2018 at 5:01 pm // Reply

    Has the study author received a lot of money from pharmaceutical laboratories and tobacco companies? It’s a simple question…

    ¿El autor del estudio ha recibido mucho dinero de laboratorios farmacéutivos y tabacaleras? Es una simple pregunta…


  4. It needs a glossary especially when you are using words like oxidative


  5. I’m an eCig smoker and this has opened my eyes to the dangers. I’m also curious about the artificial sweeteners put in the juice.


  6. Carlos Augusto Rodriguez Gomez // May 12, 2018 at 5:24 am // Reply

    por dinero y mientras existan drogadictos el mercado estara alli, pueden hacer todas sus investigaciones y podran mostrar su efectos malignos sobre los organos, pero el mercado no le importa las personas, ellos seguiran siendo los estupidos del mercado. SH

    Liked by 1 person

  7. It’s too bad that vaping is causing some pretty wealthy companies to have losses. I feel like it’s hard to trust research on it because you never know if it’s in the name of science…. or…. to sabotage the competition of big pharma / big tabacco.

    As a Vaper… I’d like the whole truth for the sake of my health.

    Liked by 1 person

  8. Prof. Riccardo Polosa // May 28, 2018 at 9:44 pm // Reply

    The experimental protocol is designed to elicit biologic as well as toxicological responses and fails to replicate normal condition of use/exposure. Therefore, the study findings overestimate the health concern associated with the exposure to some flavorings. Flavourings at high concentrations (e.g. menthol) are known to cause local irritative effects and non-specific inflammation that are usually transient and reversible. Besides, the human body is equipped with extremely efficient detoxification and scavenging systems that would take care of the exposure to potentially harmful chemicals. Human data do not confirm these concerns.

    Liked by 1 person

  9. everything is the devil to some people


  10. People need to see this, really interesting article. I had no idea that flavors were potentially harmful.


  11. So basically. They have the same effect as cigarettes when it comes to oxidative stress. However, they do not contain carbon monoxide, arsenic, and all the other harmful ingredients that cigarettes do. The article said that vaping is toxic. So are cigarettes. Bit comparing the two and their ingredients side by side. Vaping is a better option for those who want to quit. Of course the best and safest option is nothing. When you compare vaping to nothing ( nor smoking), it’s harmful. Compare it to cigarettes. It is a better option.


  12. Massimo Caruso // August 29, 2018 at 10:25 pm // Reply

    The article concludes that some chemical flavors, in particular cinnamon, vanillina and butter flavoring, are not safe for inhalation. But the authors gain this conclusion by directly exposing monocytic blood cells to e-liquids… I would suggest to the authors to conclude that “e-liquids are not safe when given in vein”. In fact, this approach is not at all comparable to the use of e-liquids (with or without chemical flavors and with or without nicotine) by electronic cigarettes!


  13. Never would’ve thought the flavorings would be the problem. So bizarre. I guess unflavored juice is the way to go? But that’s not any fun…


  14. Mixes well with other flavors.


  15. Really Interesting. Thank you for sharing.


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