2,3-Pentanedione
Marketed as a „diacetyl-free“ substitute — with near-identical lung risk.
⚠ Sounds harmless — it isn't
Wird als „diacetylfreier“ Aroma-Ersatz vermarktet, hat aber laut NIOSH ein vergleichbares Lungenrisiko (Bronchiolitis obliterans) und einen ähnlich strengen Empfehlungswert.
At a glance
- Also known as
- 2,3-Pentandion · Acetylpropionyl · AP
- CAS number
- 600-14-6
- Toxicity
Very high
- Carcinogenic
- Not classified for cancer
- In cigarette smoke
- In vape aerosol
- in vielen butter-/sahnigen Aromen als Diacetyl-Ersatz; ähnliches Lungenrisiko
What is 2,3-Pentanedione?
2,3-Pentanedione (also acetyl propionyl, AP) is a diketone with a creamy-buttery smell and chemically closely related to diacetyl. After diacetyl bans in many markets, 2,3-pentanedione has been promoted since the 2010s as a „diacetyl-free“ flavour substitute. The NIOSH 2016 risk assessment clarifies, however: lung risk is comparable to diacetyl, with the recommended shift value only marginally higher.
Why is 2,3-Pentanedione in cigarettes?
2,3-Pentanedione is deliberately used in vape flavours to create the buttery, creamy, vanilla profiles previously made with diacetyl. Since many markets (EU for e-liquids since 2016) regulate diacetyl, manufacturers switch to 2,3-pentanedione. Studies by Allen et al. (2016) found 2,3-pentanedione in over a third of tested vape liquids at health-relevant concentrations.
What 2,3-Pentanedione does to your body — short term
Acutely, 2,3-pentanedione irritates airway mucous membranes — similar to diacetyl but slightly milder. The critical feature is the same: delayed binding to proteins in the smallest bronchi (bronchioles), followed by inflammatory and scarring reactions over weeks to months.
What 2,3-Pentanedione does long term
Animal studies (Hubbs et al., 2012) show that 2,3-pentanedione at concentrations comparable to diacetyl induces bronchiolitis obliterans („popcorn lung“). The NIOSH 2016 recommendation therefore sets the 8-hour shift value in the same order of magnitude as for diacetyl. The marketing advantage „diacetyl-free“ isn't toxicologically justified — the lung risk persists.
Where else do you know 2,3-Pentanedione from?
2,3-Pentanedione occurs naturally in trace amounts in beer, honey and some cheeses — concentrations there are far below those in industrial flavour additives. Industrially it's produced as a component of butter, cream and caramel flavours for food and vape liquids.
How it compares
NIOSH's recommended exposure limit for 2,3-pentanedione is 0.034 mg/m³ (9.3 ppb as 8-hour TWA) and 0.11 mg/m³ (31 ppb as 15-minute STEL, NIOSH REL 2016) — nearly identical to diacetyl. Vape liquids with 2,3-pentanedione can concentrate exposure over many puffs per day to exceed these values.
Workplace exposure limit: 0.034 mg/m³ (9.3 ppb 8h-TWA), STEL 0.11 mg/m³ (31 ppb, 15 min), NIOSH REL 2016
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