Is Diacetyl Banned? EU vs US Status, Risks & Where It Hides
TL;DR: Diacetyl is restricted in the EU but allowed in the US (flavoring).
Also called artificial butter flavor. CAS 431-03-8.
Other names: 2,3-butanedione, artificial butter flavor, buttery flavoring
Is Diacetyl banned in the EU?
| EU status | Restricted |
|---|---|
| US status | Allowed |
| Risk level | high |
| Where it shows up | Act II Microwave Popcorn (historical), Various flavored coffees, Some margarine brands, Butterscotch candies, Some flavored chips |
| CAS number | 431-03-8 |
What is Diacetyl?
Diacetyl (2,3-butanedione) is a naturally occurring compound produced during fermentation — it is found in beer, wine, and fermented dairy. Synthetically produced diacetyl is used as an artificial butter flavoring in microwave popcorn, snack foods, and margarines. It provides the characteristic buttery aroma and taste.
Why is Diacetyl used in food?
Provides butter flavor in microwave popcorn, margarine, flavored coffee, candy, and various snacks without using actual dairy.
Is Diacetyl dangerous? Documented risks
Diacetyl is most infamously linked to 'popcorn lung' (bronchiolitis obliterans) — a severe, irreversible obstructive lung disease first identified in workers at a microwave popcorn factory in Missouri in 2000. Multiple epidemiological studies, including NIOSH investigations, have confirmed the link between occupational diacetyl inhalation and bronchiolitis obliterans. At least 30 workers developed the condition. OSHA issued a Permissible Exposure Limit (PEL) recommendation in 2016. Consumer risk from eating foods containing diacetyl is considered far lower than occupational inhalation exposure, but consumer lung injury cases from eating large amounts of microwave popcorn have been reported, including a widely cited 2012 case report in Flavor and Fragrance Journal. California enacted stricter workplace exposure limits.
Common US products containing Diacetyl
- Act II Microwave Popcorn (historical)
- Various flavored coffees
- Some margarine brands
- Butterscotch candies
- Some flavored chips
How to avoid Diacetyl: safer alternatives
Real butter, coconut oil, or yeast-derived butter-flavor compounds that do not generate diacetyl vapor provide alternative flavoring.
Frequently asked questions about Diacetyl
What is 'popcorn lung'?
Bronchiolitis obliterans — severe irreversible lung scarring caused by inhaled diacetyl vapors, documented in microwave popcorn factory workers.
Is diacetyl in all microwave popcorn?
Many brands reformulated after the popcorn lung scandal. Check labels — look for 'no artificial butter flavor' or 'diacetyl-free.'
Can eating diacetyl cause lung damage?
A 2012 case report documented lung damage in a consumer who ate large quantities of microwave popcorn daily for years. The risk from normal consumption is uncertain but much lower than occupational inhalation.
Is diacetyl banned in the EU?
Not banned, but the EU restricted its use and exposure in flavoring applications under Regulation EC 1334/2008.
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Sources
- NIOSH Health Hazard Evaluation — Bronchiolitis Obliterans in Microwave Popcorn Workers — NIOSH/CDC
- OSHA Diacetyl Technical Information — Occupational Exposure Limits — OSHA
Our scores are never influenced by brands. Last updated 6/11/2026.