Diacetyl in Flavor Concentrates

Unless stated otherwise on the individual product page, all of our flavors are made with ingredients certified for use in food. Most of our e-liquids contain a mixture of natural and/or artificial flavoring. If you have known allergies to any particular food items (e.g. nuts, fruits, sweeteners, etc) you should obviously avoid choosing flavors which are likely to contain any of the allergens you have a sensitivity to.

We do NOT add diacetyl or ingredients known to contain diacetyl, which is approved for use in food. Diacetyl (along with acetoin and acetyl propionyl) is part of a group of chemicals known as "diketones." It's often what's added to create that custard-like, buttery flavor in many food products. It's also present naturally in some fruit extracts, or it can be the result of conversion from the mixing of other chemicals. Though it's perfectly safe to ingest, the problem with diacetyl relates to inhaling it for long periods at high levels, as discovered with the development of "popcorn lung" in popcorn factory workers.

Some of our flavors indicate they may contain trace amounts of diacetyl, but this is not because we, or the flavor manufacturer added diacetyl to create the flavor.

We'll explain: The discovery of "popcorn lung" resulted in the setting of workplace limits on diacetyl exposure. Many flavor manufacturers stopped using diacetyl all together, and began using acetoin and acetyl propionyl as a replacement, but what was learned didn't necessarily eliminate all concerns where inhalation is a factor.

A 2016 British American Tobacco study tested non-acetoin, non-diacetyl e-liquids with varying PG, VG and nicotine concentrations by adding set amounts of acetoin and measuring for diacetyl over the course of several weeks. The results indicate acetoin converted to diacetyl over time, and converted at higher rates for nicotine containing liquids (though the highest conversion rate was still less than 10% of the acetoin added, resulting in only trace amounts of diacetly).

The study further tested non-diacetyl and non-acetyl propionyl e-liquids by adding diacetyl and acetyl propionyl and measuring these levels over 18 days. The results showed both chemicals actually dropped over the test period to less than half what was initially added. This indicates diacetyl and acetyl propionyl are unstable in e-liquids (likely reacting with PG and VG), and will breakdown until an equilibrium is reached.

One of the conclusions this study shows is that e-liquids containing acetoin (especially those including nicotine) are likely to form trace amounts of diacetyl, and that some of the converted diacetyl will then break down to create an equilibrium between the three tested chemicals (diacetyl, acetoin and acetyl propionyl).

All of these means its extremely difficult to prevent trace amounts of diacetyl from appearing in all e-liquids, even when it isn't added. However, by starting with and using non-diacetly ingredients, we can be sure any diacetyl present in our e-liquids will be, at most, trace amounts. Consider to, diketones detected in an actual flavor concentrates or e-liquid do not equate to what is detectable in actual e-liquid vapor (which is highly diluted by air).

But what does all this MEAN? It means with some flavors, you may still be inhaling trace amounts of diacety. But to put all this in better perspective, look at this 2015 Harvard study that reports the presence of diacetyl to be an average of 9.0 micrograms per e-cigarette cartridge (the authors of this study choose not to compare this to combustible cigarettes, but there it is).

Compare that to a 2006 study by K. Fujioka and T. Shibamoto that found diacetyl in combustible cigarettes in the range of 301 to 433 micrograms per cigarette, many times higher than contained in most e-liquids.

On the result of the Harvard study, Tobacco Analysis Blog, Dr. Michael Siegel, a Professor in the Department of Community Health Sciences at Boston University School of Public Health, states daily exposure to diacetyl from smoking is therefore 750 times higher, on average than exposure to diacetyl from vaping....Vapers are, on average, exposed to a daily dose of nine micrograms of diacetyl (a cartridge a day), compared with 6,718 micrograms for a pack-a-day smoker (emphasis mine).

He further adds even the ‘worst’ e-cigarette tested (where diacetyl was intentionally added for flavoring) produced diacetyl exposures 85 times lower (239 micrograms) than the ‘worst’ cigarette (20,340 micrograms for heavy smokers) in the study.

In conclusion, zero exposure is certainly better than some, but being armed with the facts is important when making choices. If the presence of diacetyl (or diketones in general) is a concern, you should use only flavors that do not contain any of the diketones diacetyl, acetoin or acetyl propionyl.

(Incidentally, in 2015 the CDC tested the air and surfaces in a vape shop where workers and customers vaped for diacetyl, 2,3-pentanedione, 2,3-hexanedione, acetaldehyde, acetoin, nicotine, formaldehyde, and propylene glycol and concluded concentrations of vaping-related chemicals in our air samples were below occupational exposure limits, and surface tests concluded employees’ exposures to all of the compounds quantified were well below OELs.)