Are E-cigarettes More Harmful Than Cigarettes?

Are e-cigarettes more harmful than cigarettes? A new study found that two artificial flavors used in e-cigarettes can damage lung tissue cells in laboratory experiments. These artificial flavors are safe to consume as food additives, but a researcher from Harvard University believes they may not be safe when heated and inhaled as vapor.

In a recent experiment, Joseph Allen and his colleagues exposed cultured lung epithelial cells (cells that line the surface of the lungs) to vapor from diacetyl and 2,3-pentanedione for 24 hours.

"Chemicals like diacetyl are actually quite diverse; they can be used to create flavors like butter, banana, strawberry, nutmeg, whole grain cookies, and many alcoholic flavors." In a previous study, 90% of the e-cigarettes tested by the research team contained these two chemicals.

Some flavoring chemicals used in e-cigarettes have been approved for food safety, but have not been tested for inhalation safety (Lindsay Fox, CBC)
The research team found that even at lower levels—below the recommended levels for industrial exposure—these chemicals altered gene expression in lung cells. Specifically, these chemicals appeared to interfere with the growth, production, and function of cilia, which are tiny hair-like fibers produced by these epithelial cells. Cilia work with mucus in the lungs to trap and clear pollutants that enter the lungs.

Allen stated, "Flavoring chemicals led to significant changes in gene expression in our airway epithelial cells, changes that are related to lung cilia." "Impaired cilia function is associated with lung diseases such as chronic obstructive pulmonary disease and asthma."

Inhaled chemicals are "concerning"

Allen said there is ample reason to be suspicious of these chemicals. Research from over a decade ago found that diacetyl was linked to obstructive bronchiolitis, a rare and severe lung disease later dubbed "popcorn lung" because it was commonly inhaled as heated vapor by workers in microwave popcorn processing plants.

Allen noted that workers in these factories have become aware of the dangers of inhaling these chemicals. He said there are currently no warnings for e-cigarette users.

This issue is not limited to the two chemicals he tested. These flavoring chemicals fall under the FDA's GRAS or "Generally Recognized as Safe" category. This applies to a range of substances used as food additives and flavorings. However, Allen believes this safety assumption may only apply to chemicals used in food or beverages.

He argues that we should not assume these flavorings have undergone safety testing for inhalation during the evaporation process.

He said, "The flavoring industry itself has confirmed 27 highly prioritized chemicals in a report on respiratory health and safety in flavoring manufacturing workplaces. It avoids the question of which flavorings have undergone inhalation safety testing."
Thinking of the children

This new finding is particularly concerning as the U.S. government recently released statistics. According to the Centers for Disease Control and Prevention (CDC), 20% of high school students reported having used e-cigarettes. For elementary school students, the number is much lower but still surprising at 5%.

Health Canada reports that the numbers are lower in Canada, but expresses "concern" over youth e-cigarette use.