Risk Groups and Containment Levels
Excerpts from Laboratory Biosafety Guidelines–Health Canada Laboratory Biosafety Guidelines, 3rd Edition 2004
Biological agents are classified into four categories, based on their perceived ability to cause disease in humans and animals and the level of risk to individuals and the community and is determined by particular characteristics including:
- Infectious dose
- Mode of transmission
- Host range
- Availability of effective preventative measures
- Availability of effective treatment
Risk Group 1 (low individual and community risk)
Microorganisms that are unlikely to cause disease in healthy workers or animals. These agents can be handled on an open bench top in a well designed and functional laboratory using the practices normally employed in a basic microbiology laboratory. Also referred to as Containment Level 1. (CL1)
Risk Group 2 (moderate individual risk, limited community risk)
A pathogen that can cause human or animal disease but, under normal circumstances, is unlikely to be a serious hazard to laboratory workers, the community, livestock, or the environment. Laboratory exposures rarely cause infection leading to serious disease; effective treatment and preventative measures are available and the risk of spread is limited.
Work with these agents should be done in a Containment Level 2 (CL2) laboratory, with a biological safety cabinet available for manipulations that may create an aerosol. Risk Group 2 bacteria are not uncommon isolates from natural sources - such as soil, water, food, and your body.
When working in a lab that uses Risk Group 2 bacteria you must be aware of the particular bacteria involved, and the particular risks posed by these bacteria. The primary exposure hazards associated with organisms requiring CL2 are through the ingestion, inoculation and mucous membrane route. Agents requiring CL2 facilities are not generally transmitted by airborne routes, but care must be taken to avoid the generation of aerosols (aerosols can settle on bench tops and become an ingestion hazard through contamination of the hands) or splashes. Primary containment devices such as Biological Safety Cabinets (BSCs) and centrifuges with sealed rotors or safety cups are to be used as well as appropriate personal protective equipment (i.e., gloves, laboratory coats, protective eyewear). As well, environmental contamination must be minimized by the use of handwashing sinks and decontamination facilities (autoclaves).
Risk Group 3 (high individual risk, low community risk)
A pathogen that usually causes serious human or animal disease, or that can result in serious economic consequences but does not ordinarily spread by casual contact from one individual to another, or that can be treated by antimicrobial or antiparasitic agents. These agents require a Containment Level 3 facility, which is specially constructed to minimize the chances of environmental release of biohazards. The requirements - physical, procedural, training, and testing - for a CL3 are substantially greater than those for CL1 or CL2. There is not a CL3 facility in Pathobiology and only one on University of Guelph campus.
Risk Group 4 (high individual risk, high community risk)
A pathogen that usually produces very serious human or animal disease, often untreatable, and may be readily transmitted from one individual to another, or from animal to human or vice-versa directly or indirectly, or by casual contact. No bacteria are currently classified in this group - only viruses. There is no CL4 Containment Facility on campus (and only one CL4 lab in Canada).
Worker Responsibilites When Working with BioHazardous Agents
All Lab workers should be aware that underlying and/or preexisting personal health conditions might put them at increased risk of infection when working with Level 2 Pathogens. These clinical conditions may include: open skin lesions, steroid therapy, psoriasis, splenectomy, chemotherapy, immunosuppression therapy, immunodeficiency disorders, cystic fibrosis and other chronic respiratory diseases. It is the responsibility of the lab worker to inform the Principle Investigator/Supervisor of any underlying conditions that predispose them to Level 2 pathogens.
Complying with safety procedures and wearing protective clothing, gloves, and eye wear designed for working in a Level 2 Lab are mandatory preventative measures for all personnel.