What is it and where is it found?

Diacetyl is a natural by-product of fermentation. It occurs naturally in alcoholic beverages, dairy products, fruits, plants, vegetables, meats, and natural aromas.[1] It is responsible for giving butter and some food flavourings a buttery flavour and aroma.

Diacetyl is best known as a component of microwave popcorn but is also commonly added as a flavour enhancer to snack foods, candies, baked good and pet food.[2]

How harmful is it and what are the effects?

Though the ingestion of diacetyl as a food component is relatively safe (ingesting pure diacetyl may cause nausea, vomiting and diarrhea[3]), inhalation is not. Though the general public is unlikely to come into contact with diacetyl vapours, serious respiratory illness has been linked to workers in plants producing microwave popcorn and a flavouring facility.[4] Exposure can irritate the eyes, throat and skin and lead to lung disease.

Where can it occur in e-cigarettes?

A buttery flavour or scent might indicate the presence of diacetyl. Most e-liquids are avoiding using this agent given its potential for harm when inhaled. Ironically the common replacements, including pentanedione (Acetyl Propionyl), might be just as harmful. Of the contaminants this is the only one which might have been intentionally added in order to enhance the flavour. It is worth noting that diacetyl (2,3-Butanedione) occurs in substantial levels in cigarette smoke.[5]

What is a recommended threshold for this constituent?

No threshold limit has been determined for diacetyl.[6]

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  1. https://www.osha.gov/dts/sltc/methods/validated/1013/1013.pdf
  2. https://www.osha.gov/dsg/guidance/diacetyl-guidance.html
  3. https://www.fishersci.ca/viewmsds.do?catNo=AC336040250
  4. https://www.osha.gov/dsg/guidance/diacetyl-guidance.html
  5. http://www.ncbi.nlm.nih.gov/pubmed/16463255
  6. https://www.fishersci.ca/viewmsds.do?catNo=AC336040250