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E-cigarette chemical flavorings linked to lung disease

Much of recent research regarding e-cigarettes has been focused on nicotine and other chemicals related to tobacco. However, new research has examined e-cigarette chemical flavorings – which may appeal to younger smokers – and their relationship to certain lung diseases.

Electronic cigarettes, often called a personal vaporizer, vaper,  e-cigarette, or many other trendy descriptions–I’ll abbreviate them as EC, just to save space–have become a popular alternative to tobacco cigarettes. They originally were developed as a tool to quit cigarette smoking, which is factually linked to lung cancer and other respiratory diseases.

The safety of ECs has been subject to early research, although lacking the robustness of research we have seen with tobacco. This will take time. However, some important scientific research has provided us with enough evidence that we should consider strongly regulating ECs.

Much of the research has focused on compounds found in tobacco products, such as nicotine and tar, while not looking at other chemicals that are a part of the vaping culture, such as artificial flavorings like fruits, cupcakes (really?) and cotton candy. So let’s look at this research.

Chemical flavorings and lung disease


Diacetyl, also known as butanedione, is a simple organic compound with two ketone groups.  Diacetyl occurs naturally in alcoholic beverages and is added to some foods to impart its buttery flavor.

The chemical is safe to ingest as it is found naturally in many foods, and can be used to create a buttery taste. Butterscotch’s flavor comes from diacetyl.

However, this flavoring chemical has been linked to severe respiratory disease. A study of workers in a factory that manufactured flavorings with diacetyl had higher risks of lung diseases. In fact, those individuals who had worked the longest in that factory were at 2X risk of lung diseases than those who started more recently.

According to a systematic review of diacetyl and lung disease, exposure to the chemical is associated with bronchiolitis obliterans (a serious respiratory disease that results from inflammation and fibrosis of the bronchioles leading to partial or complete obstruction of these airways), spirometry abnormalities (fixed airflow obstruction) and other respiratory symptoms.

Therefore, even though diacetyl is safe to ingest, it isn’t safe for the lungs. And this leads to an analysis of the safety of electronic cigarettes.

e-cigarette chemical flavorings


A recent study from JG Allen et al., from Harvard’s TH Chan School of Public Health, found diacetyl in more than 75 percent of flavored electronic cigarettes and refill liquids tested.  Two other potentially harmful compounds, 2,3-pentanedione, and acetoin, were also found in many of the tested flavors.

The US Occupational Safety and Health Administration have warned workers about diacetyl because of the association between inhaling the chemical and bronchiolitis obliterans. The association was first observed in workers who inhaled diacetyl containing artificial butter used in the manufacturing of microwave popcorn. It is known colloquially as “popcorn lung.”

Allen and colleagues tested 51 types of flavored e-cigarettes and liquids sold by leading EC brands for the presence of diacetyl, acetoin, and 2,3-pentanedione, related flavoring organic chemicals. To determine the levels of these compounds, the researchers inserted each EC into a sealed chamber attached to a device that drew air through the e-cigarette for eight seconds at a time with a resting period of 15 or 30 second between each draw. The drawn air was then analyzed for the compounds.

According to lead author Joseph Allen, assistant professor of exposure assessment sciences at Harvard:

[infobox icon=”quote-left”]Recognition of the hazards associated with inhaling flavoring chemicals started with ‘popcorn lung’ over a decade ago. However, diacetyl and other related flavoring chemicals are used in many other flavors beyond butter-flavored popcorn, including fruit flavors, alcohol flavors, and, we learned in our study, candy-flavored e-cigarettes.[/infobox]

In other words, diacetyl and related compounds, which have been shown to be associated with lung diseases are used in many of the flavorings favored by the electronic cigarette industry. Sadly, these flavors are also preferred by younger smokers.

The results were troublesome:

  • At least one of the three targeted organic chemicals, diacetyl, acetoin, 2,3-pentanedione,  was detected in 47 of 51 flavors tested.
  • Diacetyl was detected in 39 of 51 flavors.
  • Acetoin and 2,3-pentanedione were detected in 46 and 23 of the flavors, respectively.

The news gets worse. There are currently more than 7,000 varieties of flavored e-cigarettes and e-juice (nicotine-containing liquid that is used in refillable devices) on the market. All of these varieties potentially contain one or more of the three flavoring compounds associated with lung disease.


And even though the popularity of ECs increases dramatically, the FDA and CDC have not provided us with data regarding their safety, especially for lung disease. Now I am not a supporter of the precautionary principle, that is, don’t move forward with something unless there is a overwhelming evidence that it is safe.

On the other hand, we are starting to accumulate robust data that e-cigarettes produce or use chemicals that are linked to serious lung disease. As a result, the U.S. Food and Drug Administration (FDA) has issued a proposed rule to include e-cigarettes under its authority to regulate certain tobacco and nicotine-containing products.

The precautionary principle makes sense when more and more data is accumulated about a potential hazard. And right now, electronic cigarettes seem to produce a lot of formaldehyde, a known carcinogen, and chemicals that lead to lung disease. ECs may be safer than cigarettes, but it’s becoming clearer that it’s closer to cigarettes on the scale of lung safety.

The lungs are very susceptible to environmental damage. It’s partially because there’s little protection to the lungs cells, because their primary responsibility is to exchange air, and one cannot have a barrier, like the skin, to protect them.

Vaping is starting to appear to be dangerous. And each day more data is supporting that hypothesis. If you want cupcake flavoring, eat a cupcake. Don’t smoke a potpourri of e-cigarette chemical flavorings that have known effects to the lungs.

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Michael Simpson

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