Acetoin
Used to dodge diacetyl bans — but converts to diacetyl in the body.
⚠ Sounds harmless — it isn't
Acetoin wird oft als Ersatz für das verbotene Diacetyl in Vape-Aromen eingesetzt — wird im Körper jedoch teilweise zu Diacetyl zurückoxidiert und kann dadurch dieselben Lungenschäden auslösen.
At a glance
- Also known as
- 3-Hydroxy-2-butanon · Acetylmethylcarbinol
- CAS number
- 513-86-0
- Toxicity
Medium
- Carcinogenic
- Not classified for cancer
- In cigarette smoke
- In vape aerosol
- Häufig in buttrigen, sahnigen, vanilligen Aromen; teils als Diacetyl-Ersatz eingesetzt
What is Acetoin?
Acetoin (3-hydroxy-2-butanone) is a colourless liquid with a creamy-buttery smell and a natural component of yogurt, cream and some wines. Chemically, acetoin is closely related to diacetyl — they differ only by an OH group versus a double bond. In food acetoin is considered safe; it becomes problematic when used in e-liquids as a „safe substitute“ for diacetyl.
Why is Acetoin in cigarettes?
In vape flavours, acetoin is deliberately used to create the buttery, creamy, vanilla-like profiles that used to be made with diacetyl. Manufacturers market acetoin as „diacetyl-free“ — what they leave out: acetoin oxidises back to diacetyl during storage and when heated in the coil. Allen et al. (2016) found measurable diacetyl traces in more than half of tested „diacetyl-free“ e-liquids; LoVerme et al. (2019) demonstrated the acetoin-to-diacetyl conversion over storage time, accelerated by nicotine.
What Acetoin does to your body — short term
Acutely, acetoin acts milder than diacetyl — airway irritation is lower. The real problem is the substance's pre-inhalation history: the supposedly diacetyl-free liquid already contains measurable diacetyl by the time it's inhaled, with more forming during heating. So what's actually inhaled is both — with the same damage mechanisms for the smallest bronchi.
What Acetoin does long term
Because of the biochemical relationship with diacetyl, acetoin is also linked to the risk of bronchiolitis obliterans („popcorn lung“). Since acetoin is marketed as a substitute, there are fewer studies on long-term acetoin-aerosol effects than for diacetyl — this knowledge gap is part of the problem. Researchers at the Harvard School of Public Health explicitly warned in 2016 against considering acetoin safe.
Where else do you know Acetoin from?
You know acetoin as a natural component of yogurt, cream, butter, cheese and wine — the typical yogurt taste comes substantially from acetoin and diacetyl produced by lactic acid bacteria. Industrially, acetoin is used as a flavour component in margarine, baked goods and soft drinks; in all these oral applications it's safe.
How it compares
There's no official DFG MAK value for acetoin; ACGIH recommends a shift value of 20 ppm (roughly 70 mg/m³) — much higher than for diacetyl, because the substance appears less acutely toxic. This recommendation, however, doesn't account for the biochemical conversion to diacetyl in the body; in practice, high acetoin exposure equates to indirect diacetyl exposure with a delay.
Workplace exposure limit: kein offizieller Grenzwert (ACGIH-Empfehlung 20 ppm)
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