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Why the biological safety cabinet is no place for a Bunsen burner

posted on: December 5th, 2012
The Bunsen burner is a traditional aid to aseptic technique. However, it must never be used inside a biological safety cabinet, owing to disruption of the laminar air flow, possible damage to the HEPA filter and a high risk of fire.

Aseptic technique refers to any procedure which takes place under sterile conditions, either to prevent contamination of the product under test, or to prevent such products contaminating personnel and the environment. Flame sterilisation using a Bunsen burner is one of the first aseptic techniques that microbiologists and health professionals learn, and often used in BSL-1 (Biosafety level-1) and BSL-2 laboratories for the transfer and handling of microorganisms.

However, while BSL-2 microorganisms generally pose a low risk to humans, they include the bacteria and viruses responsible for such diseases as chlamydia, hepatitis (A, B and C), influenza A, salmonella, MRSA, Lyme disease and HIV. Therefore, a class 1 or class 2 cabinet must always be used in any procedure that could result in production of aerosols or splashes by infectious BSL-2 agents.

Placing a propane or natural gas burner in a class 2 cabinet will cause turbulence, disrupt the laminar air flow and may even damage the HEPA filter.

However, for those who feel they need it, there are various alternatives to flame sterilisation, these include:

- Alcohol burners, although the volume in the cabinet must be minimal

- Touch-sensitive micro-burners

- Electronic loop incinerators

- Disposable loops and pipettes

When used correctly, the biological safety cabinet offers a totally sterile environment, making flame sterilisation redundant.
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Contained Air Solutions Ltd, Unit 4, Greengate, Middleton Junction, Manchester, M24 1RU. Tel +44(0)161 655 8860 Fax: +44(0)161 655 8865 Email: info@containedairsolutions.co.uk