Diacetyl, the Vaping Equivalent of Gluten.

Yes, the newest vape-industry buzzword. Diacetyl has recently caught fire (not literally) in conversations among leading e-liquid manufactures and their FDA counterparts. But what in the world is it? Could it be the vaping equivalent to gluten? Let's break it down. 

Diacetyl is a naturally occurring chemical that is produced as a bi-product of yeast during the fermentation process. It's involvement in the food industry is prevalent. You may enjoy the deliciousness of diacetyl when being used as flavoring in microwavable buttered popcorn. So what's the big deal? Recently, it has earned a bad name for itself as being the probable cause of several popcorn factory workers developing what has been named "popcorn lung" (for lack of better terms) or more specifically bronchiolitis. However this is nothing to joke about. Bronchiolitis is a rare and serious fixed lung disease. (Information gathered from Wisegeek 1)

The link between diacetly and bronchiolitis has yet to be proven. However, the FDA has posted a statement regarding the issue.

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.
— Food and Drug Administration

While the FDA has listed diacetyl on their list of food products Generally Regarded as Safe (GRAS), they have yet to conduct studies in regards to the studies on the inhalation of diacetly in vapor form. According to Mt. Baker Vapor, diacetyl a common ingredient found in tobacco and has been for over 50 years. Those who smoke cigarettes or have in the past have been inhaling diacetyl for as long as they've been smoking. 

Mt. Baker Vapor does an incredible job summarizing all of this information. 

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. While the studies discussed above do not substantiate a concern for utilizing diacetyl in e-juice, we choose not to purchase from suppliers that use it in their flavoring.
— Mt. Baker Vapor

We hope our information helped you gain an understanding on diacetly!