Flavored Electronic Cigarettes Lead to Cardiac Arrhythmias in Mice

Are electronic cigarettes harmful to health?

There is a lack of scientific data to answer this question with certainty. Observations about the toxic effects of electronic cigarettes are piling up. The most recent study showed that mice had their heart rhythms altered by these flavored liquids. Vaping

Electronic cigarettes are used by many people as a substitute for traditional cigarettes. They are sometimes recommended as part of smoking cessation. Among electronic cigarette users, high school students represent a significant proportion. According to a 2017 study, nearly half of 17-year-olds have smoked them.

One of the attractions of electronic cigarettes is the wide variety of flavors they come in. The electronic cigarette liquid is heated by the cigarette to form a vapor that is then inhaled. Are these flavors, that are added to a solvent made from a mixture of 70% vegetable glycerin/30% propylene glycol with or without nicotine, safe for health?

A study published in the American Journal of Physiology, Heart and Circulatory Physiology, showed the toxic effects of certain electronic cigarette flavorings on the hearts of young mice.

Bad for the heart

At the University of South Florida, a team of researchers tested the effects of three flavors of electronic cigarettes: an exotic flavor combining passion fruit, orange, and guava; a flavor mimicking vanilla cream; and a flavor mimicking apple-cinnamon.

The toxicity of the smoke produced by these three liquids was tested in a series of in vitro experiments on mouse heart muscle cells in culture. All three fragrances induced cell death by apoptosis or necrosis, compared with cells exposed to air bursts alone, in varying proportions. Vanilla aroma appeared to be the most toxic, followed by exotic fruit aroma.

In human cardiomyocytes in culture, the researchers tested the effects of vanilla-flavored vapor on their electrical activity. The vapor produced by a liquid consisting only of the solvent did not alter the cells’ electrical activity. However, the electrical activity decreased when nicotine was added and even more so in the presence of the vanilla cream flavor. The cultured, cells exposed to flavored smoke contracted less frequently. “This experiment has shown us that flavorings added to electronic cigarettes can increase the damage beyond what nicotine alone can do,” Sami Noujaim, a researcher involved in the study, said in a news release.

Health effects still under debate

These disorders observed in the Petri dishes are also present in young mice. In an in vivo experiment, the researchers placed 10-week-old mice in a “vaping chamber” where they were exposed to vanilla-scented vapor five days a week for 10 weeks. The result: after 10 weeks, the exposed mice showed fluctuations in the time between heartbeats – in other words, cardiac arrhythmias. The researchers believe that the smoke alters the autonomic nervous control of the heart rhythm.

It is difficult to say whether these observations can be applied to humans. Studies on volunteers are needed to provide more clarity and to know which fragrances are most toxic. A large number of Americans believe that electronic cigarettes are less harmful than traditional cigarettes. The scientific literature on this topic continues to grow, with sometimes conflicting conclusions that reflect ongoing uncertainties about the health effects of electronic cigarettes.