Biosafety Cabinets- Definition, Classes (I, II, III) and Types

Biosafety cabinets (BSCs) are enclosed, ventilated laboratory workspaces for safely working with materials contaminated with (or potentially contaminated with) pathogens requiring a defined biosafety level. BSCs are also called biological safety cabinets or microbiological safety cabinets. BSCs first became commercially available in 1950.

BSCs are one type of biocontainment equipment used in biological laboratories to provide personnel, environmental, and product protection. Most BSCs (e.g., Class II and Class III) use high efficiency particulate air (HEPA) filters in both the exhaust and supply system to prevent exposure to biohazards.

The primary purpose of BSCs is to protect the laboratory personnel and the environment from the pathogenic microorganisms as aerosols might be formed during the processing of such microorganisms. All exhaust air is HEPA-filtered as it exits the biosafety cabinet, removing harmful bacteria and viruses.

BSCs are different from laminar flow clean benches, which blow unfiltered exhaust air towards the user and are not safe for work with pathogenic agents. Neither are most BSCs safe for use as fume hoods, which fail to provide the environmental protection that HEPA filtration in a BSC would provide.

BSCs are classified into three classes by the U.S. Centers for Disease Control and Prevention (CDC), each with specific performance characteristics and applications. These classes and the types of BSCs within them are distinguished by the level of personnel and environmental protection provided and the level of product protection provided.

The use of BSCs or other such physical containment is not required in the biosafety level 1, but depending on the risk assessment, some processes might require such containment. BSCs are an essential part of biosafety as they minimize the formation of aerosol, protecting the environment, the pathogen, and the laboratory personnel. Besides, most BSCs also function to sterilize biological materials that are kept inside the cabinets.

Biosafety cabinets (BSCs) are one type of biocontainment equipment used in biological laboratories to provide personnel, environmental, and product protection. They are designed to prevent exposure to biohazards, such as pathogenic microorganisms, that may be present or generated during microbiological processes .

BSCs work by creating a directional airflow that draws air from the laboratory into the cabinet and then filters it before releasing it back into the laboratory or the environment . The air is filtered by high efficiency particulate air (HEPA) filters that remove biological contaminants . Depending on the class and type of BSC, the air may also be recirculated within the cabinet to provide product protection.

The primary purpose of BSCs is to protect the laboratory worker and the surrounding environment from the potential hazards of aerosols that may be formed during the manipulation of biological materials . Aerosols are small droplets or particles that can carry infectious agents and can be inhaled or deposited on surfaces. BSCs reduce the risk of aerosol formation and exposure by creating a physical barrier and a negative pressure gradient between the cabinet and the laboratory .

Another purpose of BSCs, especially Class II and Class III cabinets, is to protect the product or sample from contamination by external sources . This is achieved by supplying HEPA-filtered air over the work surface and preventing cross-contamination within the cabinet. Product protection is important for maintaining the quality and integrity of biological materials, such as cell cultures, tissue samples, or diagnostic specimens .

BSCs are not the same as laminar flow clean benches or fume hoods, which have different purposes and functions . Laminar flow clean benches only provide product protection by blowing unfiltered air towards the user, but they do not protect the user or the environment from biohazards . Fume hoods only provide user and environmental protection by exhausting chemical vapors or gases, but they do not protect the product from contamination or filter the exhaust air .

BSCs are an essential part of biosafety as they minimize the exposure to biohazards and maintain the sterility of biological materials. However, BSCs alone are not sufficient to ensure biosafety; they must be used in conjunction with appropriate microbiological techniques, personal protective equipment, laboratory practices, and waste management . Moreover, BSCs must be selected, installed, maintained, and serviced according to the specific biosafety level and risk assessment of each laboratory .

Biosafety cabinets and laminar hoods are both enclosed workspaces with a ventilated hood that are designed to provide a clean and sterile environment for handling biological materials. However, they have different functions and levels of protection depending on the type of work and the risk of exposure to pathogens or contaminants.

A biosafety cabinet (BSC) provides environmental, personnel and product protection from hazardous particulates and biohazards. It draws air away from the laboratory worker and releases it into the atmosphere through HEPA filters. It also creates a barrier of air between the operator and the work surface to prevent contamination. A BSC is required when there is a degree of potential hazard associated with the proposed experiment, it involves volatile substances, or the results need to be protected from ambient contamination. BSCs are classified into three classes (I, II, III) and five types (A1, A2, B1, B2, C1) by the CDC, each with specific performance characteristics and applications.

A laminar hood (LH), also known as a laminar flow clean bench or a laminar flow hood, provides product protection from environmental contaminants, but not personnel or environmental protection. It passes filtered air through HEPA filters while maintaining a constant air velocity in a particular direction. It protects only the product or specimen from contamination by particulates such as microorganisms. A LH is suitable for non-hazardous products that are safe for an operator to inhale. It should not be used for handling hazardous materials or chemicals that may generate fumes or aerosols. LHs are classified into two types: vertical and horizontal, depending on the direction of the airflow.

The main difference between a BSC and a LH is that a BSC protects all three: the product, the user and the environment, while a LH protects only the product. A BSC recirculates some of the air within the cabinet and exhausts some of it to the outside, while a LH recirculates all of the air within the bench. A BSC has a front opening that allows the entry of the operator`s arms during work, while a LH has a closed front that prevents direct contact with the product. A BSC has different biosafety levels (1-4) that correspond to different risk groups of organisms and processes, while a LH does not have such levels.

Therefore, it is important to choose the appropriate type of equipment based on the nature of the work and the level of protection required. A BSC is more suitable for working with infectious microorganisms or hazardous substances that require biosafety containment, while a LH is more suitable for working with non-infectious or non-hazardous materials that require cleanliness and sterility.

Biosafety levels (BSL) are a set of biocontainment precautions required to isolate dangerous biological agents in an enclosed laboratory facility. They are ranked from one to four, based on the level of protection provided to workers, the environment, and the public. The levels are defined and specified by the Centers for Disease Control and Prevention (CDC) in the United States.

Biosafety cabinets (BSCs) are enclosed workspaces with a ventilated hood that are designed to contain pathogenic microorganisms during microbiological processes. The primary purpose of biosafety cabinets is to protect the laboratory personnel and the environment from the pathogenic microorganism as aerosols might be formed during the processing of such microorganisms.

The use of biosafety cabinets or other such physical containment is not required in the biosafety level 1 (BSL-1), but depending on the risk assessment, some processes might require such containment. BSL-1 applies to laboratory settings in which personnel work with low-risk microbes that pose little to no threat of infection in healthy adults — for example, a BSL-1 laboratory might work with a nonpathogenic strain of E.coli. BSL-1 labs typically conduct research on benches, do not use special contaminant equipment, and do not need to be isolated from surrounding facilities.

Class I and II Biosafety cabinets are used for Biosafety levels I and II but, when used correctly in conjunction with useful microbiological techniques, these provide an effective containment system for safe manipulation of moderate and high-risk microorganisms. BSL-2 applies to laboratory settings in which personnel work with agents that can cause human disease if accidentally inhaled, swallowed, or exposed to the skin — for example, a BSL-2 laboratory might work with Staphylococcus aureus or Salmonella typhimurium. BSL-2 labs require specific practices and procedures, such as wearing gloves and lab coats, using biological safety cabinets for aerosol-generating procedures, and having self-closing doors.

Class III Biosafety cabinets are most suitable for work with hazardous agents that require Biosafety Level 3 or 4. BSL-3 applies to laboratory settings in which personnel work with agents that can cause serious or potentially lethal disease through inhalation — for example, a BSL-3 laboratory might work with Mycobacterium tuberculosis or Bacillus anthracis. BSL-3 labs require more stringent practices and procedures than BSL-2 labs, such as wearing respirators and protective clothing, using biological safety cabinets for all manipulations of agents, and having separate areas for decontamination and waste disposal.

Class III Biosafety cabinets are leak-tight, totally enclosed but ventilated cabinets, where all air that either enters or leaves through the facility pass through a HEPA filter. These cabinets are also termed ‘glove boxes’ as they have rubber gloves attached to the system to be used during operations in the cabinet. These cabinets are essential for the manipulation of biological materials in the Biosafety level 4 (BSL-4). BSL-4 applies to laboratory settings in which personnel work with agents that pose a high risk of life-threatening disease or aerosol-transmitted infections — for example, a BSL-4 laboratory might work with Ebola virus or Marburg virus. BSL-4 labs require the most stringent practices and procedures than any other biosafety level, such as wearing full-body suits with positive pressure ventilation, using biological safety cabinets for all manipulations of agents, and having separate buildings or isolated zones for laboratory activities.

In summary, biosafety cabinets are used in different biosafety levels depending on the risk group of the microorganisms being handled and the potential for aerosol formation. The higher the biosafety level, the more protective measures are required for biosafety cabinets and other aspects of laboratory safety.

Biosafety cabinets (BSCs) are an important component of biosafety in laboratories that handle infectious microorganisms or biological materials. BSCs provide a physical barrier between the operator and the biological agents, preventing exposure to aerosols that may contain pathogens or recombinant DNA. BSCs also protect the biological materials from contamination by external sources, ensuring the quality and integrity of the research.

BSCs are designed to create a directional airflow that draws air from the front opening of the cabinet and passes it through high-efficiency particulate air (HEPA) filters before exhausting it to the environment or recirculating it within the cabinet. HEPA filters remove 99.97% of particles that are 0.3 micrometers or larger, effectively trapping biological contaminants and preventing their release. BSCs also have a negative pressure relative to the surrounding room, which prevents any leakage of contaminated air from the cabinet.

BSCs are classified into three classes (I, II, and III) and five types (A1, A2, B1, B2, and C1) based on their performance characteristics and applications. Each class and type of BSC has different levels of protection for the operator, the product, and the environment, depending on the biosafety level (BSL) of the laboratory and the risk group of the microorganisms. BSCs should be selected, installed, used, and maintained according to the guidelines and standards established by the U.S. Centers for Disease Control and Prevention (CDC), the National Institutes of Health (NIH), and other relevant organizations.

BSCs are essential for ensuring a safe and productive work environment in biological laboratories. They reduce the risk of infection and exposure to hazardous biological agents for the laboratory personnel and the public. They also prevent cross-contamination and interference with the biological materials being handled. BSCs are therefore a vital tool for conducting high-quality research in microbiology, biotechnology, medicine, and other related fields.

Biosafety cabinets are classified into three classes by the U.S. Centers for Disease Control and Prevention (CDC), each with specific performance characteristics and applications . The classification is based on the level of protection provided to the personnel, the product, and the environment.

• Class I Biosafety Cabinet: This class provides protection to the personnel and the environment, but not to the product. It has an open front design that allows room air to enter the cabinet and flow over the work surface. The air is then exhausted through a high-efficiency particulate air (HEPA) filter before being discharged to the environment or recirculated to the laboratory . Class I biosafety cabinets are suitable for working with low to moderate risk biological agents (biosafety level 1 or 2) that do not require product protection .

• Class II Biosafety Cabinet: This class provides protection to the personnel, the product, and the environment. It has a vertical laminar airflow design that creates a barrier of clean air between the operator and the work surface. The air is also HEPA-filtered before entering and leaving the cabinet . Class II biosafety cabinets are further divided into five types depending on the exhaust system and the amount of recirculation of air within the cabinet: Type A1, Type A2, Type B1, Type B2, and Type C1. Class II biosafety cabinets are suitable for working with moderate to high risk biological agents (biosafety level 2 or 3) that require product protection .

• Class III Biosafety Cabinet: This class provides maximum protection to the personnel, the product, and the environment. It is a totally enclosed and ventilated cabinet that operates under negative pressure. The operator accesses the work area through glove ports or sleeves attached to the cabinet. The air is HEPA-filtered before entering and leaving the cabinet, and may also be treated by other methods such as incineration . Class III biosafety cabinets are suitable for working with high risk biological agents (biosafety level 4) that pose a significant threat to human health and require maximum containment .

Class I biosafety cabinets are the simplest and most basic type of biosafety cabinets that provide protection to the environment and the laboratory personnel. They do not, however, protect the product or the sample from contamination as the unfiltered room air is drawn over the work surface.

Class I biosafety cabinets are typically used for processes that generate aerosols or involve equipment that might release hazardous particles into the air. For example, they can be used to enclose centrifuges, blenders, sonicators, or aerating cultures. They can also be used for handling low-risk microorganisms that do not require product protection.

Class I biosafety cabinets have a front opening that allows the operator to access the work area. The room air is drawn in through this opening by a fan mounted at the top of the cabinet. The air then flows over the work surface and carries away any aerosols or particles that may have been generated. The air is then passed through a high-efficiency particulate air (HEPA) filter before being exhausted to the environment or recirculated back to the laboratory.

The HEPA filter removes 99.97% of particles that are 0.3 micrometers or larger in size, thus providing protection to the environment from potential pathogens. The inward airflow also creates a barrier that prevents the contaminated air from escaping back to the operator, thus providing personnel protection.

Class I biosafety cabinets can be either ducted or unducted. Ducted cabinets are connected to the building exhaust system and discharge the filtered air outside the laboratory. Unducted cabinets recirculate the filtered air back to the laboratory through a vent on top of the cabinet. Ducted cabinets are preferred when working with volatile chemicals or odorous substances that need to be removed from the laboratory.

Class I biosafety cabinets are suitable for biosafety level 1 and 2 laboratories, where product protection is not required or where low-risk microorganisms are handled. They are not suitable for biosafety level 3 and 4 laboratories, where high-risk microorganisms require maximum containment and product protection. They are also not suitable for working with sterile or sensitive samples that might be contaminated by the unfiltered room air.

Class I biosafety cabinets are easy to operate and maintain, but they have some limitations and disadvantages. Some of them are:

• They do not provide product protection and may contaminate the sample with unfiltered room air.
• They have limited workspace and visibility due to the front opening and the airflow direction.
• They may generate noise and vibration due to the fan operation.
• They may interfere with other equipment or airflow patterns in the laboratory due to their exhaust or recirculation vents.

• They may require additional ventilation or cooling systems to prevent overheating or accumulation of chemical vapors inside the cabinet.

  Class II Biosafety Cabinet: protection and principle of operation

Class II biosafety cabinets (BSCs) are the most common type of BSCs used in laboratories that handle moderate-risk microorganisms. They provide protection to the operator, the environment, and the product (sample) by using a combination of inflow and downflow air streams that are filtered through high-efficiency particulate air (HEPA) filters.

The principle of operation of Class II BSCs is based on the following steps:

• A fan mounted on the top of the cabinet draws air from the room into the front opening of the cabinet, creating a negative pressure zone that prevents the escape of contaminated air from the work area.
• The inflow air passes through a HEPA filter before entering the cabinet, ensuring that it is free of contaminants.
• The inflow air then splits into two streams: one that flows downward over the work surface (downflow) and one that flows upward behind the work surface (exhaust).
• The downflow air creates a laminar (smooth and uniform) flow that prevents cross-contamination between different samples or areas on the work surface. The downflow air also protects the product from contamination by the operator or the environment.
• The exhaust air is either recirculated back into the cabinet after passing through another HEPA filter or discharged outside the cabinet through a duct system. The exhaust air also protects the operator and the environment from exposure to aerosols or vapors generated within the cabinet.
• The HEPA filters remove 99.97% of particles that are 0.3 micrometers or larger in size, effectively trapping microorganisms and other contaminants.

Class II BSCs are further classified into five types (A1, A2, B1, B2, and C1) based on their airflow patterns, exhaust systems, and applications. Each type has different advantages and limitations depending on the type and amount of hazardous materials being handled. The following table summarizes the main features and differences between these types:

Class II BSCs should be used in accordance with proper biosafety practices and procedures, such as wearing appropriate personal protective equipment (PPE), decontaminating the work surface and equipment before and after use, and disposing of waste materials safely. Class II BSCs should also be certified annually by qualified personnel to ensure their optimal performance and safety.

Types of Class II BSCs: A1, A2, B1, B2, and C1

Class II biosafety cabinets are the most common type of biosafety cabinets used in biological laboratories. They provide protection to the personnel, the environment, and the product from exposure to biohazards. Class II biosafety cabinets have a front access opening with an inward airflow that prevents the escape of contaminated air. They also have a vertical laminar airflow that passes through HEPA filters before entering and leaving the work area.

Class II biosafety cabinets are further divided into five types based on their airflow patterns, exhaust systems, and applications. These types are A1, A2, B1, B2, and C1.

• Type A1: This type has a minimum inflow velocity of 75 feet per minute (fpm) and recirculates about 70% of the air within the cabinet. The remaining 30% of the air is exhausted through a HEPA filter either to the room or to a thimble connection to the building exhaust system. Type A1 cabinets are suitable for work with biosafety level 1, 2, or 3 agents that do not produce volatile chemicals or radionuclides .
• Type A2: This type has a minimum inflow velocity of 100 fpm and recirculates about 70% of the air within the cabinet. The remaining 30% of the air is exhausted through a HEPA filter either to the room or to a thimble connection to the building exhaust system. Type A2 cabinets are similar to Type A1 cabinets but have higher inflow velocity and lower noise level. They are also suitable for work with biosafety level 1, 2, or 3 agents that do not produce volatile chemicals or radionuclides .
• Type B1: This type has a minimum inflow velocity of 100 fpm and recirculates about 30% of the air within the cabinet. The remaining 70% of the air is exhausted through a HEPA filter to a dedicated duct system with an exhaust fan. Type B1 cabinets have a partial barrier between the work area and the exhaust plenum that allows some of the contaminated air to be directly exhausted. They are suitable for work with biosafety level 1, 2, or 3 agents that produce minute quantities of volatile chemicals or radionuclides .
• Type B2: This type has a minimum inflow velocity of 100 fpm and does not recirculate any air within the cabinet. All of the air is exhausted through a HEPA filter to a dedicated duct system with an exhaust fan. Type B2 cabinets have no barrier between the work area and the exhaust plenum and have a higher ventilation rate than other types. They are suitable for work with biosafety level 1, 2, or 3 agents that produce moderate to high quantities of volatile chemicals or radionuclides .
• Type C1: This type is a hybrid of Type A and Type B cabinets that can operate in either mode depending on the need. It has a minimum inflow velocity of 105 fpm and can recirculate about 60% of the air within the cabinet in Type A mode or exhaust all of the air through a HEPA filter to a dedicated duct system with an exhaust fan in Type B mode. Type C1 cabinets have a single-pass airflow system that allows them to switch modes without changing filters or ducts. They are suitable for work with biosafety level 1, 2, or 3 agents that produce variable quantities of volatile chemicals or radionuclides.

The choice of the type of Class II biosafety cabinet depends on several factors such as the nature of the biological agents, the presence and amount of chemical substances, the availability and cost of ductwork and exhaust systems, and the space and layout of the laboratory. The proper use and maintenance of Class II biosafety cabinets are essential for ensuring their optimal performance and safety.

Class III Biosafety Cabinet: protection and usage

Class III biosafety cabinets are the most advanced and secure type of BSCs that provide the highest level of protection to the operator, the environment, and the product. They are designed for handling the most hazardous biological agents that require biosafety level 4 containment.

Class III BSCs are also known as glove boxes because they are completely sealed and isolated from the laboratory environment. The operator can only access the work area through attached rubber gloves that prevent any direct contact with the biological materials. The gloves also limit the hand movement and dexterity of the operator inside the cabinet.

The cabinet has a double-door autoclave or a dunk tank for sterilizing the materials before they enter or exit the work area. The cabinet also has a transfer chamber for passing materials in and out of the cabinet without compromising the containment.

The cabinet is ventilated by a dedicated exhaust system that draws air into the cabinet through HEPA filters and exhausts air out of the cabinet through double HEPA filters or HEPA filters plus incineration. The cabinet is maintained under negative pressure to prevent any leakage of contaminated air into the laboratory.

Class III BSCs are suitable for working with highly infectious microorganisms that can cause severe or fatal diseases in humans or animals, such as Ebola virus, Marburg virus, Lassa fever virus, etc. They are also used for manipulating toxins, radioactive materials, carcinogens, or other hazardous substances that require maximum containment.

Class III BSCs are usually custom-built for specific laboratories and applications. They may have built-in equipment such as microscopes, centrifuges, incubators, etc. inside the work area. They may also have interconnecting modules to allow more workspace or flexibility.

Class III BSCs require special training and maintenance to ensure their proper functioning and safety. They are expensive to install and operate and consume a lot of energy and resources. They are not widely available and are mostly found in specialized research facilities or high-security laboratories.

Class II biosafety cabinets are the most common type of biosafety cabinets used in biological laboratories. They provide protection to the personnel, the environment, and the product from exposure to biohazards. Class II biosafety cabinets have a front access opening with an inward airflow that prevents the escape of contaminated air. They also have a vertical laminar airflow that passes through HEPA filters before entering and leaving the work area.

Class II biosafety cabinets are further divided into five types based on their airflow patterns, exhaust systems, and applications. These types are A1, A2, B1, B2, and C1.

• Type A1: This type has a minimum inflow velocity of 75 feet per minute (fpm) and recirculates about 70% of the air within the cabinet. The remaining 30% of the air is exhausted through a HEPA filter either to the room or to a thimble connection to the building exhaust system. Type A1 cabinets are suitable for work with biosafety level 1, 2, or 3 agents that do not produce volatile chemicals or radionuclides .
• Type A2: This type has a minimum inflow velocity of 100 fpm and recirculates about 70% of the air within the cabinet. The remaining 30% of the air is exhausted through a HEPA filter either to the room or to a thimble connection to the building exhaust system. Type A2 cabinets are similar to Type A1 cabinets but have higher inflow velocity and lower noise level. They are also suitable for work with biosafety level 1, 2, or 3 agents that do not produce volatile chemicals or radionuclides .
• Type B1: This type has a minimum inflow velocity of 100 fpm and recirculates about 30% of the air within the cabinet. The remaining 70% of the air is exhausted through a HEPA filter to a dedicated duct system with an exhaust fan. Type B1 cabinets have a partial barrier between the work area and the exhaust plenum that allows some of the contaminated air to be directly exhausted. They are suitable for work with biosafety level 1, 2, or 3 agents that produce minute quantities of volatile chemicals or radionuclides .
• Type B2: This type has a minimum inflow velocity of 100 fpm and does not recirculate any air within the cabinet. All of the air is exhausted through a HEPA filter to a dedicated duct system with an exhaust fan. Type B2 cabinets have no barrier between the work area and the exhaust plenum and have a higher ventilation rate than other types. They are suitable for work with biosafety level 1, 2, or 3 agents that produce moderate to high quantities of volatile chemicals or radionuclides .
• Type C1: This type is a hybrid of Type A and Type B cabinets that can operate in either mode depending on the need. It has a minimum inflow velocity of 105 fpm and can recirculate about 60% of the air within the cabinet in Type A mode or exhaust all of the air through a HEPA filter to a dedicated duct system with an exhaust fan in Type B mode. Type C1 cabinets have a single-pass airflow system that allows them to switch modes without changing filters or ducts. They are suitable for work with biosafety level 1, 2, or 3 agents that produce variable quantities of volatile chemicals or radionuclides.

The choice of the type of Class II biosafety cabinet depends on several factors such as the nature of the biological agents, the presence and amount of chemical substances, the availability and cost of ductwork and exhaust systems, and the space and layout of the laboratory. The proper use and maintenance of Class II biosafety cabinets are essential for ensuring their optimal performance and safety.

Class III biosafety cabinets are the most advanced and secure type of BSCs that provide the highest level of protection to the operator, the environment, and the product. They are designed for handling the most hazardous biological agents that require biosafety level 4 containment.

Class III BSCs are also known as glove boxes because they are completely sealed and isolated from the laboratory environment. The operator can only access the work area through attached rubber gloves that prevent any direct contact with the biological materials. The gloves also limit the hand movement and dexterity of the operator inside the cabinet.

The cabinet has a double-door autoclave or a dunk tank for sterilizing the materials before they enter or exit the work area. The cabinet also has a transfer chamber for passing materials in and out of the cabinet without compromising the containment.

The cabinet is ventilated by a dedicated exhaust system that draws air into the cabinet through HEPA filters and exhausts air out of the cabinet through double HEPA filters or HEPA filters plus incineration. The cabinet is maintained under negative pressure to prevent any leakage of contaminated air into the laboratory.

Class III BSCs are suitable for working with highly infectious microorganisms that can cause severe or fatal diseases in humans or animals, such as Ebola virus, Marburg virus, Lassa fever virus, etc. They are also used for manipulating toxins, radioactive materials, carcinogens, or other hazardous substances that require maximum containment.

Class III BSCs are usually custom-built for specific laboratories and applications. They may have built-in equipment such as microscopes, centrifuges, incubators, etc. inside the work area. They may also have interconnecting modules to allow more workspace or flexibility.

Class III BSCs require special training and maintenance to ensure their proper functioning and safety. They are expensive to install and operate and consume a lot of energy and resources. They are not widely available and are mostly found in specialized research facilities or high-security laboratories.

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