The Health and Safety Executive (HSE) has issued a safety alert regarding exposure to Diacetyl vapour.

Diacetyl, also known as 2,3-butanedione, is a naturally occurring organic compound but is also manufactured synthetically. It is often used as a flavouring and is a by-product of coffee roasting, but the HAS warns that even when used at low concentrations within mixtures or flavourings, exposure to its vapour may be above safe workplace exposure limits (WELs) and can lead to severe and irreversible lung disease.

HSE scientific studies have shown that airborne concentrations and the potential for exposures above safe workplace limits is significantly increased if flavour mixtures containing diacetyl, even at low concentrations (below 5%) are heated, added to hot processes or spray dried.

Risk of exposure can occur during:

• opening of diacetyl or flavouring containers

• decanting and weighing

• mixing

• spray drying to produce powdered mixtures

• packaging

• cleaning of vessels or spillages

What you should do:

The HSA recommend that if your processes include the use of diacetyl, food flavourings that contain diacetyl, or are likely to produce diacetyl, then you must carry-out a risk assessment to help you to identify the hazards associated with the potential for exposure, understand who might be harmed and how, evaluate the risks and decide on precautions.

If diacetyl is not mentioned on a safety data sheet for food flavourings (which are likely to contain it) you should contact the supplier to confirm if it is present or not.

If there is a potential for diacetyl exposure use sampling and analysis to verify whether exposure is likely to be above the WEL.

Substitute to a safer alternative product.  Substitutes should not contain compounds similar to diacetyl such as 2,3-pentanedione.

If substitution is not a viable option (for example if diacetyl is a natural by-product), then strict controls must be implemented.

You will find more detail of how to control the risk here