Module 04 - Occupational Health and Safety

Biosafety Guidelines and Levels of Containment

Please note: the information provided here will give the reader a general understanding of the levels of biohazard control required to work with biohazardous agents safely in animal facilities. It is not intended to be definitive or complete.

Quote from the Health Canada Laboratory Biosafety Guidelines,

"The attitudes and actions of those who work in the laboratory determine their own safety, and that of their colleagues and of the community. Laboratory equipment and design can contribute to safety only if they are used properly by people who are genuinely concerned and knowledgeable about safety issues."

Biohazards are rated at four levels with a risk group associated with each level. Containment levels refer to the physical requirements and risk groups refer to the pathogenicity of the organisms. Biosafety Level 1 is required to manage the lowest risk and Biosafety Level 4 is required to manage the highest risk to human or animal health.

Biosafety Level 1

Risk Group 1 infectious agents are biological agents that are unlikely to cause disease in healthy workers or animals (low individual and community risk).

Facilities required to contain risk group 1 organisms - Containment Level 1: No special facilities, equipment or procedures are required. Standard well-designed experimental animal and laboratory facilities and basic safe laboratory practices suffice. Hand-washing facilities must be provided. Disinfectants must be properly used.

Biosafety Level 2

Risk Group 2 infectious agents are pathogens that can cause human or animal disease but, under normal circumstances, are unlikely to be a serious hazard to laboratory workers, the community, livestock, or the environment (moderate individual risk, limited community risk). Laboratory exposures rarely cause infection leading to serious disease; effective treatment and preventive measures are available and the risk of spread is limited.

Risk Group 2 infectious agents include, for example: E. coli; many salmonella; some fungi like ringworm; California encephalitis viruses; human herpes simplex viruses; many influenza viruses; Transmissible Gastro-enteritis of swine; Mouse Hepatitis Virus; and a few parasites.

Facilities, equipment, and procedures required to contain risk group 2 organisms at Level 2: Laboratory separated from other activities, biohazard sign, room surfaces impervious and readily cleanable. Equipment should include an autoclave, certified HEPA filtered class I or II biological safety cabinet for organism manipulations, and personal protective equipment to include laboratory coats worn only in the laboratory, gloves worn when handling infected animals. All contaminated material to be properly decontaminated.

Biosafety Level 3

Risk Group 3 infectious agents are pathogens that usually cause serious human or animal disease, or which can result in serious economic consequences, but do not ordinarily spread by casual contact from one individual to another (high individual risk, low community risk), or that can be treated by antimicrobial or antiparasitic agents.

Risk Group 3 pathogens include bacteria such as anthrax, Q Fever, tuberculosis, and viruses such as hanta viruses, Human immunodeficiency viruses (HIV - all isolates), eastern and western equine encephalitis viruses.

Facilities, equipment and procedures required to contain risk group 3 organisms include: Specialized design and construction of laboratories, with controlled access double door entry and body shower. All wall penetrations must be sealed. Ventilation system design must ensure that air pressure is negative to surrounding areas at all times, with no recirculation of air; air exhausted through a dedicated exhaust or HEPA filtration system. Minimum furnishings, all readily cleanable and sterilizable (fumigation). Laboratory windows sealed and unbreakable. Backup power available.

Equipment must include an autoclave, certified HEPA filtered class II biological safety cabinet for organism manipulations, and a dedicated handwashing sink with foot, knee or automatic controls, located near the exit. Personal protective equipment should include solid front laboratory clothing worn only in the laboratory, head covers and dedicated footwear, gloves worn when handling infected animals and appropriate respiratory protection, depending on the infectious agents in use.

Exit procedures should include showers, depending on infectious agents used and manipulations involved. All animal wastes to be disposed of as contaminated laboratory materials. All activities involving infectious materials to be conducted in biological safety cabinets or other appropriate combinations of personal protective and physical containment devices.

Laboratory staff must be fully trained in the handling of pathogenic and other hazardous material, in the use of safety equipment, disposal techniques, handling of contaminated waste, and emergency response. Standard Operating Procedures must be provided and posted within the laboratory outlining operational protocols, waste disposal, disinfection procedures and emergency response. The facility must have a medical surveillance program appropriate to the agents used, which includes serum storage for all personnel working in the containment laboratory and an accident report system.

Biosafety Level 4

Risk Group 4 infectious agents are pathogens that usually produce 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 (high individual risk, high community risk).

Risk Group 4 infectious agents are all viruses, such as, Ebola viruses, Herpes B virus (Monkey virus), Foot and Mouth Disease.

Containment Level 4 is the highest level of containment and represents an isolated unit that is completely self-contained to function independently. Facilities are highly specialized, secure with an air lock for entry and exit, Class III biological safety cabinets or positive pressure ventilated suits, and a separate ventilation system with full controls to contain contamination.

Only fully trained and authorised personnel may enter the Level 4 containment laboratory. On exit from the area, personnel will shower and re-dress in street clothing. All manipulations with agents must be performed in Class III biological safety cabinets or in conjunction with one-piece, positive-pressure-ventilated suits.

The following table summarizes the biosafety levels.