Biosafety Cabinet (BSC) - is an enclosed, ventilated laboratory workspace for safely working with materials contaminated with (or potentially conmtaminated with) pathogens requiring a defined biosafety level (BSL). The primary purpose of a BSC is to serve as a means to protect the laboratory worker and the surrrounding environment from pathogens. All air is HEPA-filtered as it exits the BSC, removing harmful bacteria and viruses. Many (but not all) types of BSCs are also designed to maintain the sterility of the materials being worked with.
Note: Chemical fume hoods are not designed nor intended to be used as BSCs. Chemical fume hoods fail to provide the environmental protection that HEPA filtration in a BSC would provide. Likewise, a laminar flow clean bench can not be used as a BSC. A laminar flow clean bench blows unfiltered exhaust air towards the user and is not safe for work with pathogenic agents.
For a thorough description of BSCs, including selection, installation, and use please see Appendix A of the Biosafety in Microbiological and Biomedical Laboratories Guidelines (6th ed.)
If work is being performed in a BSL-2 laboratory, all work in which infectious aerosols may be produced must be conducted in a BSC or other type of physical containment. If work is being performed in a BSL-3 laboratory, all work must be performed in a BSC or other type of physical containment.
Work Practices and Procedures
- Cabinet blowers should be operated at least 3-5 minutes before beginning work to allow the BSC to "purge" particulates.
- Turn off BSC Ultraviolet (UV) light (if present) before beginning work.
- Appropriate personal protective equipment must be worn. Lab coats must be buttoned. Gloves should be pulled over the knitted wrists of the lab coat, not worn inside the coat.
- Place only the necessary materials in the BSC before beginning work.
- Extra supplies (gloves, plates, media, etc.) should be stored outside BSC: material placed inside BSC may cause disruption to the airflow.
- Move arms in and out of BSC slowly, perpendicular to the face opening to reduce disruption of air curtain. Manipulation of materials should be delayed momentarily to allow air circulation to stabilize.
- Do not block front grille with papers or materials or rest arms on front grille. This allows room air to flow directly into the work area rather than being drawn through the front grille. Work with arms raised slightly.
- All operations should be performed at least 4 inches from the front grille on the work surface.
- Interior walls, interior surface of the window, and the surfaces of all materials to be placed in the BSC should be wiped with 70% ethanol or other appropriate disinfectant before and after each use. If bleach is used, make sure that it is followed by sterile water or 70% ethanol. Bleach will eventually ruin the stainless steel surfaces of the BSC.
- Plastic backed absorbent toweling can be placed on the work surface (but not on the front grille) to aid in cleanup and spill containment.
- Active work should flow from the clean to contaminated area across the work surface.
- To minimize frequent in/out arm movement and maintain air barrier, do not tape autoclavable biohazard collections bags to the outside of the BSC and upright pipette collection containers should not be used in the BSC nor placed on the floor outside the BSC (use horizontal discard trays containing an appropriate chemical disinfectant within the BSC).
- Potentially contaminated materials should not be brought out of the BSC until they have been surface decontaminated.
- Use techniques to reduce splatter and aerosol generation: Open bottles or tubes should not be held in a vertical position, hold the lid above open sterile surfaces to minimize direct impact of downward air, open flames create turbulence which disrupts the pattern of air supplied to the work surface and should not be used. If necessary, touch plate microburners which provide a flame on demand or electric furnaces are available. All flames must be off before disinfectants are used.
- Aspirator bottles or suction flasks should be connected to an overflow collection plastic flask containing an appropriate disinfectant, and to an in-line HEPA filter.
- If spilled liquid enters through the front or rear grilles, close the drain valves and pour decontaminating solution into the drain pans. After 20-30 minutes, collect the spilled liquid and disinfectant with paper towels.
Biosafety Cabinet Certifications
- All BSCs should be certified annually. If Biosafety Level 2 or higher materials are used in the BSC, the cabinet must be certified annually.
- If the BSC is relocated, it must be re-certified prior to use.
United States. Department of Health and Human Services. Primary Containment for Biohazards:
Selection, Installation and Use of Biological Safety Cabinets. Washington, D.C: U.S. Government
Printing Office, 1995.