Diacetyl in E Liquid: A Review

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Diacetyl… In MY E Liquid?

Ever since the early 2000s, when microwave popcorn manufacturers had 7 cases of Bronchiolitis across 28 different flavor manufacturers, people have been worried about what is in their food and flavorings. Daily working exposure to the pure powdered form of Diacetyl in areas with little filtration or air flow, has an association with what you might have heard called “popcorn lung”. Diacetyl is one of three flavor compounds called Diketones that are looked at as potentially issue causing.

Research by Dr. Farsalinos has found Diketones in 74.2% of e liquid samples that he has studied, with Diacetyl being the main compound one found. From his study:

“The median daily exposure levels were 56 μg/day (IQR: 26-278 μg/day) for DA… They were slightly lower than the strict NIOSH-defined safety limits for occupational exposure and 100 and 10 times lower compared with smoking respectively…”

Compared with smoking? Yes, cigarettes have had diacetyl in them for a long time! Dr. Siegel found in his study that the average smoker inhales 6,700 micrograms of Diacetyl per day, with upto 20,000 micrograms for heavy smokers. From his website:

Table 2. Maximum inhaled daily diacetyl dose associated with smoking vs. vaping
Vaping: 239 micrograms
Smoking: 20340 micrograms (see Pierce et al., 2014)

Thus, the “worst” e-cigarette tested produces diacetyl exposure that is 85 times lower than that of the “worst” cigarette tested.

Diacetyl in Cigarette-Smoke
Diacetyl in Cigarette-Smoke

So cigarette smoke can produce much more diacetyl than even some of the worst offenders in e liquid manufacturing. These numbers are at the high end of smoking and vape usage.

According to studies done on the connection between smoking cigarettes and “popcorn lung” show little risk associated. The Science Journal Critical Reviews in Toxicology says:

We found that diacetyl and 2,3-pentanedione exposures from cigarette smoking far exceed occupational exposures for most food/flavoring workers who smoke. This suggests that previous claims of a significant exposure–response relationship between diacetyl inhalation and respiratory disease in food/flavoring workers were confounded, because none of the investigations considered or quantified the non-occupational diacetyl exposure from cigarette smoke, yet all of the cohorts evaluated had considerable smoking histories. Further, because smoking has not been shown to be a risk factor for bronchiolitis obliterans, our findings are inconsistent with claims that diacetyl and/or 2,3-pentanedione exposure are risk factors for this disease.

So the jury is still out on whether diacetyl causes bronciolitis. Even still, knowing there are risks that could be avoidable, we try to avoid flavor companies that use diketones as ingredients for their flavorings. Flavor Apprentice, one of our major flavor suppliers, has DX varieties of their flavors, specifically formulated to remove Diketones like diacetyl. Capella has moved onto version 2 of their delicious Vanilla Custard. If you’re nervous about any of our flavorings, just ask and we can provide more information for you on all of our e liquid flavors.


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