First let’s talk about what diacetyl is and why it is of interest to anyone. Diacetyl (fyi, I pronounce it as di-ah-SEE-till, but there are other ways to say it) and it’s relatives, such as acetyl propionyl, belong to the family that chemists call alpha-diketones. These compounds have the characteristic of imparting a buttery sensation to foods. They are used in a wide variety of products such as baked goods (cakes and cookies), confections (candy and chocolates), and snacks (potato or corn chips).
Diacetyl became a concern when food workers in plants making butter-flavored microwave popcorn started having health problems. Subsequent toxicology studies with rats tagged the high levels of diacetyl fumes from the imitation butter flavoring used as contributing to the problem, … at least in part.
A pretty well-known maxim in the science of toxicology states that, when it comes to chemicals and people, it’s the dose that makes the difference. For example, moisture (water) is only a small fraction of a percent in humid air and is often desirable, particularly if one lives in Arizona. However, breathing 100% water (i.e., drowning) is not recommended. In a more familiar case, most prescription medicines can be toxic in too large doses.
As for the question of diacetyl (or acetyl propionyl) in ecigs, it is true that these diketones are also used in some artificially flavored e-cigarettes to achieve that same buttery/creamy flavor note. Some tobacco flavors and most creamy blends have it. (Without the acetyl propionyl, would butter rum just be rum and butterscotch just be … scotch?) Also recognize that the flavor blends that do contain diketones have very very small amounts of the ingredient. A 1-milliliter charge of e-liquid blend may contain micrograms of diacetyl or acetyl propionyl (not both). And most of that is exhaled when vaped.
How much may be harmful is a question that even the CDC and OSHA can’t precisely answer. The popcorn workers were continuously exposed to high concentrations of numerous fume components in the factory over a long period of time. Under normal conditions for the average person, is it possible to smell too many butter cookies? Vaping falls in the same intermittent, low-exposure category. Alternately, we offer many flavors (fruit, dessert, etc.) that have none of the ingredient in question. Unfortunately, listing all the flavors with or without diketones is impractical here. Feel free to contact us for suggestions.
Ph.D. chemist Dr. Tony Pace.
- BS Chemistry - University of Florida
- PhD Chemistry - University of Texas, Austin
- Robert A Welch Foundation Research Fellowships
- Adjunct Professor of Chemistry - Emory University, Atlanta
- Visiting Research Fellow - Georgia Institute of Technology, Chemistry Dept.
- 25 years experience in Industrial R&D with Fortune 500 companies
- Holds 3 US Patents
- Has 7 Journal Publications