WORKING IN A BIOLOGICAL SAFETY CABINET

BTO

Biological Services Ltd.

Risk Group Definitions• Risk Group 1

Low individual and community riske.g., E.coli K12, Lactobacilli,

• Risk Group 2Moderate individual risk, low community riske.g., Staphylococcal species, enterotoxigenic Escherichia coli, Shigella species, Salmonella species

• Risk Group 3High individual risk, low community riskM. tuberculosis, C.burnetii,

• Risk Group 4High individual risk, high community riske.g., Ebola virus

Biological Agent

• Biological agents include but are not limited to:Bacteria ParasitesFungi Viral vectorsViruses Recombinant productsRickettsiae Prions

Cultured human or animal cellsand the potentially infectious agents they might contain

Biohazard

• A biohazard is a biological agent or a biological material that is potentially hazardous to a life form

• The manipulation of a biological agent or biological material so that the capacity or potential to produce infection or disease in a living form is present

Aerosols

• DefinitionAn aerosol is a liquid or particulate suspended in a gaseous medium

• Size range is from 0.01 microns – 100 microns

• Health relevant fractions of aerosols

inhalable 0.01-100 micronsnasopharyngeal deposition 25-100 micronstracheobronchial deposition 5-25 micronsalveolar deposition 0.01-5 microns

Route of Transmission & Entry

• Inhalation

• Ingestion

• Inoculation

• Direct or indirect contact

Biological Safety Cabinets

• Bad terminologyLaminar flow cabinetsTissue culture cabinetsSterile benches

• Good terminologyBiological Safety cabinetsBiosafety cabinets

• In general, BSC’s are classified according to the method by which air volumes are recirculated or exhausted.

Air Cleaning Device

• The primary air cleaning device in biological safety cabinets is a HEPA filter (High Efficiency Particulate in Air)

• HEPA filters do not provide protection against volatiles gases or vapours – only particulates

Filter Efficiency

• HEPAA minimum efficiency of capture is 99.97% for 0.3 micronsAny particulate bigger or smaller than 0.3 microns is captured more efficiently than 99.97%

Biosafety cabinet review

• When do you work in a Class II BSC?

• When there is potential to create aerosols

• When you need to protect yourself, the product and the environment

Types of BSC’s

• Class IProtects the environment and the user – does not protect the product

It is a partial containment device and is suitable for work involving low to moderate risk agents (containment levels 1, 2 and 3)

User and environmental protection is made possible by constant unidirectional movement of air into the cabinet, away from the user through HEPA filtration before re-entry into the environment. The product is not protected

Types of BSC’s• Class II

The Class II biological safety cabinet has three key features:(i) A front access opening with carefully maintained inward airflow. (ii) HEPA-filtered, vertical, unidirectional airflow within the work area.

(iii) HEPA-filtered exhaust air to the room or exhaust to a facility exhaust system.

Subtypes of Class II BSC’s

• Class IIA1predominant cabinet protects the product user and environment

• Class IIA2protects the product user and environment

• Class IIB1protects the product, user and environment can be used with small amounts of volatiles and gases

• Class IIB2protects the product, user and environment

Class IIA BSC’s

Class IIA BSC’s

Class IIA BSC’s

• Air curtain between sash and work surface is critical to containment

Working in a Class IIA BSC

• Whenever there is potential for aerosol generation you must work in a BSCe.g., manipulating human or animal tissues or fluids; opening a closed centrifuge cupafter centrifugation, taking spent media off Tissue culture.

• You need to employ good techniquee.g., employ good start up procedures; disinfect everything you need to work with into the BSC prior to commencing work; do not block the grilles; be seated at the right height; ensure that nothing you need to use is outside the cabinet --------

Working in a Class IIA1 BSC• Place everything you need to work

with inside the cabinet

• Purge to establish airflow

• Separate clean items from dirty items

• Don’t pass dirty items over clean ones

• Do not block the front intake grille

• Work on plastic backed absorbent material – for quick clean ups

Fire in BSC

UV Radiation

• UV germicidal lamps produce UV light at 253.7 nm wavelength (40 Wcm-2) - this has limited penetrating power

• The intensity or destructive capability of UV decreases by the square of the distance from the lamp

• Exposure time is always related to distance

• The intensity of the lamp also decreases with time

UV Radiation

• The intensity of the lamp is drastically affected by the accumulation of dust and dirt on it

• UV lights should never be on while someone is working in the cabinet

• UV lights should not be left on while anyone is in the area and likely to be exposed to reflected UV radiation