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Chemical & Biological Hazards Project

Safety & Health Assessment & Research for Prevention (SHARP) — Research for Safe Work

Food flavorings and diacetyl

Food flavorings are a complicated mixture of compounds that may include a chemical called diacetyl (also known as 2,3-Butanedione). Diacetyl imparts a buttery taste to food. It is a chemical that is naturally present at low concentrations in a wide variety of foods such as dairy, beer, coffee, honey and fruits. There is increasing scientific evidence that links diacetyl exposure to a severe form of lung disease called bronchiolitis obliterans. It is not clear whether diacetyl exposure alone is capable of causing disease, or whether it is diacetyl along with mixtures of volatile organic compounds that result in disease. While much is unknown regarding the toxicity of food flavorings and diacetyl, steps can be taken in the workplace to reduce employee exposure to these chemicals.

In food manufacturing, diacetyl is added to a wide range of foods. Examples include: butter, cheese, milk, flour mixes, cookies, crackers, candy and confectionery products, chocolate and cocoa products, shortening, food oils, margarines, flavored syrups, potato chips, corn chips, ready-to-mix desserts, prepared frosting and gelatin desert preparations. People who make or work near flavorings in the production and packaging of food may be at risk for diacetyl exposure in the form of vapors, dusts or sprays.

To identify whether diacetyl is in the materials you may be handling, check container labels and product Material Safety Data Sheets (MSDS). Diacetyl has the Chemical Abstract Service (CAS) number 431‑03‑8 and should be listed in Section 2 of the MSDS. However, because diacetyl is often present in low quantities, it may not be specifically listed on the MSDS sheet.

More information

SHARP has produced information to help employers and employees work safely with food flavorings and diacetyl:

Food flavorings and diacetyl publications
Number Title/Description
64‑12‑2008 2008 Letter to Physicians Regarding Food Flavorings (42 KB PDF).
SHARP's letter to encourage physician recognition and reporting of food flavoring lung disease.
64‑11‑2008 Cocina usted con aceitas de sabor artificial a mantequilla o sustitutos de mantequilla (55 KB PDF). Spanish version of "Information for Restaurant Owners and Workers about Diacetyl".
64‑10‑2008 Information for Restaurant Owners and Workers about Diacetyl (48 KB PDF).
64‑9‑2006 Letter to Physicians Regarding Food Flavorings (21 KB PDF).
Bronchiolitis obliterans is an uncommon disease that can be easily misdiagnosed. SHARP's letter to physicians highlights symptoms and the suggested medical evaluation.
64‑8‑2006 Safety and Health Alert for Flavorings and Flavoring Ingredients (56 KB PDF).
64‑7‑2006 Letter to Employers Regarding Food Flavorings (36 KB PDF).

If you are located in Washington State, you can contact the Safety & Health Assessment & Research for Prevention (SHARP) Program at Labor & Industries for more help. The SHARP program can provide assistance regarding workplace exposures and medical evaluations. Contact SHARP at 1‑888‑667‑4277 or

Please see the NIOSH Flavorings-Related Lung Disease ( Web page for comprehensive information about this topic.

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