Fumigation of Biological Safety Cabinets

Decontamination of biological safety cabinets is required prior to maintenance or testing.

(Refer to section 7.9 of AS 2647-1994, Biological safety cabinets – Installation and use.)

Why fumigation is necessary

Internal plenums (spaces) of biological safety cabinets become contaminated by aerosols of hazardous micro-organisms, which have been handled in the cabinet. These internal plenums need to be accessed during testing and maintenance.
In the past we have used formaldehyde to fumigate cabinets. However, owing to the cytotoxic nature of and unpleasant side effects of expsosure to formaldehyde, our current preferred method uses hydrogen peroxide.
The latter is just as capable of rendering microbiological contamination harmless and thus minimising the risk of personnel exposure to microbiological hazards.

Exceptions

If the cabinet user can guarantee (in writing) that no hazardous organisms have been used in the cabinet since it was last fumigated, we will test the cabinet without prior fumigation.

How a cabinet is fumigated

The following method is based on recommendations of a UK document known as the Howie Report published by Department of Health and Social Security (1983). The cabinet is sealed, usually with plastic film. The fumigant(s) are then introduced. Either Hydrogen peroxide vapour is pumped into the cabinet, or in the case of a formalin fumigation, the formalin solution and potassium permanganate are mixed in a chamber within the cabinet. In the second scenario the chemical reaction produces formaldehyde vapour which permeates every space within the cabinet and neutralises microbiological organisms over a 12 hour period. The formaldehyde is neutralised by ammonia prior to the cabinet seal being removed. In the first scenario, the hydrogen peroxide generator pumps vapour into the cabinet for 4-5 hours, depending on the size of the cabinet. This vapour permeates every space within the cabinet and readily neutralises microbiological organisms. It is then ready to test after a short airing period.

Application and removal of the fumigation kit should be performed by a trained technician or by any person trained in the safe handling of chemicals and equipment in a laboratory and equipped with appropriate protective devices.

NB:Owing to difficulties in obtaining small quantities of formaldehyde, Camfil Farr will cease to supply fumigation kits once the current stock has run out.

- Last updated 3rd Sept 2010 -

Our trained Technicians can also apply and/or clear the fumigation kit from the cabinet.