Principles of Biosafety

The term "containment" is used in describing methods for managing infectious agents in the laboratory environment where they are being handled or maintained. The purpose of containment is to reduce exposure of laboratory employees, other persons and the outside environment to potentially hazardous or infectious agents. The three elements of containment include laboratory practices and techniques, safety equipment and facility design. Primary containment, the protection of personnel and the immediate laboratory environment from exposure to infectious agents, is provided by good micro-biological technique and the use of appropriate safety equipment. Secondary containment, the protection of the external laboratory environment from exposure to infectious materials, is provided by a combination of facility design and operational practices. 

A. Laboratory Practice and Technique

The most important element of containment is strict adherence to standard microbiological practices and techniques. Persons working with infectious agents or infected materials must be aware of potential hazards and be trained and proficient in the practices and techniques required for handling such material safely. The lab manager and lab supervisor is responsible for providing or arranging for appropriate training of personnel with assistance from EH&S. Additional measures may be necessary when standard laboratory practices are not sufficient to control the hazard associated with a particular agent or laboratory procedure. The selection of additional safety practices is the responsibility of the lab manager and lab supervisor and must be commensurate with the inherent risk associated with the agent or procedures. An example of an additional practice would be a vaccination requirement. (See Appendix 5 for vaccination recommendations) 

B. Safety Equipment

Such equipment includes biological safety cabinets and a variety of enclosed containers. The biological safety cabinet (BSC) is the principal device used to provide containment of infectious aerosols generated by many microbiological procedures. Three types of BSC’s (Class I, II, III) used in microbiological labs are described in Appendix 6. Openfronted Class I and Class II BSC’s are partial containment cabinets which offer significant levels of protection to laboratory personnel and to the environment when used in conjunction with good microbiological techniques. The gas-tight Class III BSC provides the highest attainable level of protection to personnel and the environment. An example of an enclosed container is the capped centrifuge bottle which prevents the release of aerosols during centrifugation. Safety equipment also includes items for personal protection such as gloves, coats, gowns, shoe covers, boots, respirators, face shields, and safety glasses. These personal protective devices are often used in combination with biological safety cabinets and other devices which contain the agents, animals and materials being worked with. In some situations in which it is impractical to work in biological safety cabinets, personal protective devices may form the primary barrier between personnel and the infectious materials. Examples include certain animal studies, animal necropsy, production activities and activities relating to maintenance, service or support to the laboratory. 

C. Facility Design

The design of the facility is critical for providing protection to persons outside the laboratory and in the community in the event that an infectious agent is accidentally released in the laboratory. It is the responsibility of the lab manager, EH&S, Physical Facilities and Facilities Planning to provide lab facilities commensurate with the function of the laboratory. The following information describes three facility designs, in ascending order of containment level. 

1. Basic Laboratory
   This laboratory provides general space appropriate for work with defined viable agents which are not associated with disease processes in healthy adults or which do not colonize in humans. All activities are regularly conducted on the open bench using standard laboratory practices. 
2. Containment Laboratory
   This laboratory provides general space appropriate for work with infectious agents or potentially infectious materials when the hazard levels are low and laboratory personnel can be adequately protected by standard laboratory practices. Work is commonly conducted on the open bench with certain operations confined to BSC’s. Conventional laboratory designs are adequate. Areas known to be sources of general contamination such as animal rooms and waste staging areas should not be adjacent to media, processing areas, tissue culture laboratories or patient care activities. Public areas and general offices to which nonlaboratory staff require frequent access should be separated from spaces which primarily support laboratory functions. 
3. High Containment Laboratory
   This laboratory has special engineering features which make it possible for laboratory workers to handle hazardous materials without endangering themselves, the community or the environment. The unique features which distinguish this laboratory from the basic and containment laboratories are the provisions for access control, a specialized ventilation system and vacuum line isolation (See Appendix 6). The high containment laboratory may be an entire building or a single module or complex of modules within a building. In all cases, the laboratory is separated by a controlled access zone from areas open to the public and laboratory personnel.