I. IntroductionBiological Safety Cabinet is the primary engineering control that provides user, sample, and environment protection against biohazards. A biosafety cabinet’s airflow consists of an inflow barrier that prevents the accidental release of biohazards from the cabinet’s working area. It also has a downflow air that removes contaminants from the work zone, providing a sterile area for the samples. Show
A BSC should be selected based on the following criteria: type of work, classification of biohazards (Risk Group 1-4); personnel protection against exposure to radionuclides and volatile toxic chemicals; or a combination of these. The table below shows which BSCs are recommended for each type of protection.
Source: Laboratory Biosafety Manual. 3rd ed (revised). Interim guidelines. World Health Organization. p52. Esco Lifesciences is a world leader in biological safety cabinets, offering the industry’s widest product range, with thousands of installations in leading laboratories in more than 100 countries around the globe. Esco biological safety cabinets have earned more independent certifications in more countries, in more languages, than any other product, demonstrating our commitment to the industry’s best safety and quality. Class I Biological Safety Cabinets The Class I biosafety cabinet has the most basic and rudimentary design of all BSCs available today. It offers protection to the operator and the environment from exposure to biohazards and is suitable for work with microbiological agents assigned to biosafety levels 1, 2, and 3. Class II Type A2 Biological Safety Cabinets The Class II Type A2 biological safety cabinet is the most common Class II BSC. It is also the most common biosafety cabinet of all the different types available. It has a plenum from which 30% of air is exhausted, and 70% is re-circulated to the work area as the downflow. It protects the operator and the environment from exposure to biohazards and protects products from contaminated room air and cross-contamination. If trace amounts of toxic chemicals are employed as an adjunct to microbiological processes, Type A cabinets should be exhaust-ducted. Class II Type B2 Biological Safety Cabinets A Class II Type B2 biological safety cabinet is designed to have no recirculation within the cabinet. The inflow and downflow air is exhausted after HEPA filtration to the external environment. Type B2 biosafety cabinets are suitable for work with toxic chemicals employed as an adjunct to microbiological processes as there is no recirculation. In theory, Type B2 BSCs may be considered as the safest of all Class II BSCs since the total exhaust feature acts as a fail-safe if the downflow and/or exhaust HEPA filtration system cease to function normally. Class III Biological Safety Cabinet The Class III biological safety cabinet provides an absolute level of safety, which cannot be attained with Class I and Class II biosafety cabinets. It is suitable for work with microbiological agents assigned to biosafety levels 1, 2, 3, and 4. It is frequently specified for work involving the most lethal biological hazards. II. Biosafety Cabinet Guide to modelsIII. Must-have features of a BSCEnsured containment of biohazards with Esco biological safety cabinets Containment refers to the ability of the cabinet/enclosure to contain all hazardous particles inside the working space without any escape through the front of the cabinet. The most recognized way to test the containment of a biological safety cabinet in the field and after manufacture is through the KI-DISCUS test. It should be noted that a cabinet can pass all the airflow tests but still fail the containment test. Esco Lifesciences is one of the few companies outside Europe with KI-DISCUS testing capabilities. In addition, all our biological safety cabinets have been type-tested and approved for containment using this method. Aside from KI-DISCUS, microbiological tests such as product and cross-contamination protection tests are also employed. These tests determine whether:
Esco Biosafety Cabinet features:
IV. Factors to Consider When Selecting a Biosafety CabinetSelection Based on Biosafety Level Biosafety levels are measures to contain or isolate harmful infectious agents in a laboratory. For risk assessment of harmful agents, a Biological Safety Officer (BSO) and Institutional Biosafety Committees (IBC) may be of help. There are four biosafety levels: Biosafety Level 1 is for undergraduate and secondary educational training, teaching laboratories, and for other laboratories that use microorganisms that are not pathogenic. Examples are Bacillus subtilis, Naegleria gruberi, and infectious canine hepatitis virus. Thus, BSL-1 containment only requires a sink for handwashing. Biosafety Level 2 is appropriate for clinical, diagnostic, teaching, and other laboratories which deal with indigenous moderate-risk agents linked with human disease and is present in a community. Examples are the Hepatitis B virus, HIV, Salmonella, and Toxoplasma. These microorganisms may be used on the open bench as long as there is low production of aerosols. Hazards may be acquired through ingestion of or exposure of the mucous membrane from the microorganisms. Certain precautions should be taken in handling contaminated materials (i.e. sharp objects). Similarly, procedures involving aerosol should be undertaken in BSC or safety centrifuge cups. Personal protective equipment is also effective together with handwashing sinks and waste decontamination facilities. Biosafety Level 3 applies to clinical, diagnostic, teaching, research, or production facilities handling indigenous or exotic agents with a potential for respiratory transmission that may be a cause for lethal infection. Examples are Mycobacterium tuberculosis, St. Louis Encephalitis virus, and Coxiella burnetii. Hazards may be acquired through autoinoculation, ingestion, and exposure to infectious aerosols. For containment, procedures should be done in BSC or a gas-tight aerosol generation chamber. Ventilation systems should also be appropriate to reduce the release of hazardous aerosols. Biosafety Level 4 is appropriate for life-threatening hazardous agents or pathogens which may be spread through the aerosol route and has no available vaccine or therapy. Examples are Marburg or Congo-Crimean hemorrhagic fever. Hazards may be acquired through infectious aerosols, skin membrane exposure to hazardous droplets, and autoinoculation. To isolate the infectious agents completely, procedures should be done in Class III BSC or while in a full-body air-supplied positive-pressure personnel suit. The BSL-4 laboratory is located in an isolated complex with specialized ventilation and waste management systems. The entire operation of the laboratory should be handled by a laboratory director. A supplement to this will be the presence of trained laboratory personnel, safety measures/manuals, safety equipment, appropriate design of facilities, personal protective equipment, and biosafety level practices.
Selection Based on the Filtration system One of the most important components of a BSC is the filter. Currently, there are two kinds of filters that a biological safety cabinet utilizes:
ULPA filter is 10 times more efficient than the HEPA filter, thus a biosafety cabinet with an ULPA filter can provide better operator, product, and environmental protection. Selection Based on Possibility to Block Inflow Grille The operator and product protection are achieved through the air curtain created by both the inflow and downflow that goes into the front air grille. The user needs to select a BSC design that can prevent accidental blocking on the grille by operator arms or samples. There are several ways to prevent the inflow grille blocking:
Figure 1. Combination of raised armrest and curved inflow grille to prevent accidental blocking. Selection Based on Airflow Alarm There are different possibilities for alarms and control systems used by biosafety cabinets:
Selection Based on Front Window Mechanism, Material, and Angle A biosafety cabinet has different window mechanisms wherein the user must select the most convenient type without compromising containment.
Figure 2: Sample photo of a smashed tempered glass sash. Tempered glass or laminated safety glass are ideal materials for the sash of biosafety cabinets. Most tempered glasses are UV absorbing, clear, and will retain their shape when shattered to avoid any containment failure or accidents. The sash can either be a vertical window or a sloped one. Vertical windows are easier to design but will provide eye strain to the operators. Modern biosafety cabinets have an angled front or sloping to provide better visibility while minimizing glares and reflections. Selection Based on Work Trays For safety, the BSC’s surface needs to be decontaminated before and after use, or after a large spillage occurs. Therefore, the cleanability factor plays an important role in selecting a Biosafety Cabinet:
Selection Based on Ergonomics Biosafety cabinets should be equipped with ergonomic features as this will provide comfort and increase productivity. Here are several features to consider when selecting a biosafety cabinet:
V. Safety Tips When Using Biosafety Cabinets
Tips on how to properly work in a Biosafety Cabinet Biological Safety Cabinets are used for handling pathogenic samples or for applications requiring a sterile work zone. It protects the user from biohazards with an airflow barrier created by the inflow air. Simultaneously, samples inside the cabinet are also protected by downflow air that creates another airflow barrier. However, the effectiveness of the biosafety cabinet is only as good as how the operator uses it. Here are several tips on how to work safely in your biosafety cabinet:
Which of the following statements accurately reflects the range of engineering controls used for protection against biohazard?Which of the following statements accurately reflects the range of engineering controls used for protection against biohazards? Engineering controls can be sophisticated devices (such as biosafety cabinets) and very simple devices (such as bench shields or biohazard waste receptacles).
Which of the following is a common feature of all biosafety cabinets quizlet?The common feature in all BSCs is the high efficiency particulate air (HEPA) filter. HEPA filters can remove particles down to 0.3 microns with 99.97% efficiency and will trap most bacteria and viruses.
Which of the following is a good work practice when centrifuging biohazards quizlet?Which of the following is a good work practice when centrifuging biohazards? Decontaminate the exterior of tubes, safety buckets, and/or sealed rotors before removal from the biosafety cabinet.
Which of the following is a requirement for a bsl3 laboratory?Common requirements in a BSL-3 laboratory include: Standard personal protective equipment must be worn, and respirators might be required. Solid-front wraparound gowns, scrub suits or coveralls are often required. All work with microbes must be performed within an appropriate BSC.
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