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Is diacetyl in e-liquid really harmful?

Here at Flagship Vapor Co. we choose to create flavors that are rich and satisfying to our customers, and as a result some of our e-liquids may contain some amount of diacetyl. Further test results are pending.  We use flavorings from the industry leading flavoring manufactures to produce e-liquids that are of top notch quality, and all of our premium e-liquids are manufactured inside of a clean room environment. Vaping has always been viewed as a “safer alternative to smoking” we along with any respectable e-liquid companies have never claimed to be 100% safe, just safer than smoking combustable cigarettes. Actual research goes to show that vaping is still safer that smoking even with liquids that contain diacetyl.  So please take some time and read the below post, hopefully it will bring some clarity to the issue, and put your concerns at rest. 

Due to a recent article published by Harvard we have received several emails regarding diacetyl in our liquids. We were going to write a big long blog post about it, explaining everything and hoping to help bring some light to the issue, but we found that there was a ton of info already available online addressing the concerns. 

Below is a re-blog from our friends at Mt. Baker Vapor concerning diacetyl in e-liquids. 


Wisegeek 1 gives this definition of diacetyl:

 A naturally occurring chemical that is produced as a byproduct of yeast during the fermentation process. Used in a wide variety of food products, it is best known as a flavoring in microwave buttered popcorn. Most recently, diacetyl has earned a bad name for being the probable cause of several popcorn factory workers developing what has been dubbed ‘popcorn lung’, or bronchiolitis. This is a rare and serious fixed obstructive lung disease.

In the 1990’s, factory workers in a microwave popcorn plant contracted bronchiolitis, also known as ‘popcorn lung’. It was generally believed that this was the result of inhaling a powdered form of diacetyl, in very high concentrations, which is used in the butter flavoring for the popcorn.

While it is generally believed that the cause of popcorn lung was inhalation of powdered diacetyl, this has yet to be proven, as we will see shortly in the information provided by the CDC. It is important to note that the FDA has posted the following statement about the consumption of diacetyl on their website 2,

Diacetyl is added to some foods for flavoring purposes. It is metabolized in mammals, is of low acute toxicity, and the no-adverse-effect level is estimated to be less than .3mg. There is no evidence on the available information on diacetyl that demonstrates or suggests reasonable grounds to suspect a hazard to the public when they are used at levels that are now current or that may reasonably be expected in the future.

The FDA has listed Diacetyl on their Generally Regarded as Safe (GRAS) list of food additive products, yet they have not made a statement regarding the safety of the inhalation of diacetyl in vapor form. As mentioned above, it hasn’t been proven that diacetyl was the cause of the popcorn-lung, as seen by the article published by the CDC 3 to address their views on diacetyl titled Flavorings-Related Lung Disease in which they state

Diacetyl is a chemical that was found to be a prominent volatile constituent in butter flavoring and air at the microwave popcorn plant initially investigated. Workers in microwave popcorn manufacturing are exposed to many materials besides diacetyl. Thus, initial studies in a total of 6 microwave popcorn plants were not able to definitely determine if diacetyl exposure contributed to lung disease or was a marker for other hazardous substances that contributed to disease. Current evidence, however, points to diacetyl as one agent that can cause flavorings-related lung disease. While other flavoring ingredients may also play a role.

Meaning, while they cannot prove that diacetyl was the cause of the disease, they do consider it a primary area of concern. The diacetyl inhaled by these factory workers was in powder form, used to add a buttery flavor to the microwave popcorn they were producing. However, when vaping there is obviously no powder being inhaled, so does this concern relate to vaping?

It may not be common knowledge, but diacetyl is a common ingredient in tobacco, and has been for over 50 years. Meaning, those who have been smoking cigarettes, have been inhaling diacetyl this whole time. The Critical Reviews in Toxicology 4 group conducted a study simply titled Diacetyl where they concluded,

 Diacetyl exposures from cigarette smoking far exceeded occupational exposures for most food/flavoring workers. This suggests that previous claims of a significant exposure-response relationship between diacetyl inhalation and respiratory disease in food/flavoring workers were confounded. Further, smoking has not been shown to be a risk factor for bronchiolitis (popcorn lung).

To summarize their findings, they found that the levels of diacetyl in tobacco were significantly higher than those found in the factories where the popcorn lung was contracted, bringing into question the diacetyl as the cause of the condition. Further, they found that smoking cigarettes, regardless of the higher levels of diacetyl has not been shown to cause popcorn lung. Looking at e-juice in relation to tobacco levels of diacetyl the Nicotine & Tobacco Research 5 group conducted a study Evaluation of Electronic Cigarette Liquids and published these results, “The purpose of this study was to evaluate sweet-flavoured electronic cigarette (EC) liquids for the presence of diacetyl (DA). DA was found in 74.2% of the samples. They were lower than the strict safety limits for occupational exposure and 110 times lower compared to smoking respectively.” This tells us first, that there is diacetyl in analog cigarettes at 110 times higher levels than those found in the e-juices they studied. Secondly this tells us the amounts they found in the e-juice were within the safety limits of exposure.

To summarize, studies like those conducted above show that there is a significantly higher amount of diacetyl exposure from smoking than there is in the factories where the production workers got sick, presumably (but not proven to be) due to exposure to diacetyl inhalation. There are no documented cases of popcorn-lung being developed from smoking. Considering that studies show, as indicated above, that the amount of diacetyl in analog cigarettes is 110 times higher than amounts found in the e-liquids tested, and there are no cases of diacetyl related sickness from smoking, I would conclude that the levels of diacetyl found in some of the e-cig juices are relatively safe.

As always, I encourage everyone to educate themselves. Read the studies and information listed in the references below, and learn more about the realities and misconceptions surrounding the subject of diacetyl.

Written by: Michelle Harnden

Wisegeek “What is Diacetyl”

FDA “Diacetyl”

CDC “Flavorings-Related Lung Disease”

Critical Reviews in Toxicology Diacetyl”

Nicotine & Tobacco Research “Evaluation of electronic cigarette liquids” 



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