Risk groups and BioSafety Levels - An Overview - What Every Biochemist Must Know!
Author: Sweta Kumari
Pathogens that cause infectious disease in human or animals are called as risk groups. The consideration used for biological risk assessment to determine appropriate biosafety level in which the procedure can be conducted is primarily infectious biological agents. Another consideration is the ability of microorganisms to cause diseases in human or animals, activities performed in the laboratory, training and health of laboratory worker, etc. microorganisms are classified into four risk groups:
Risk Group 1(RG-1):
Microorganisms are not associated with disease in healthy adult humans or animals. (no or low individual and community risk) e.g: E.coli K-12, lactobacilli.
Risk Group 2(RG-2):
Agents are associated with human or animal disease which is rarely serious to laboratory workers, the community or environment and for which preventive or therapeutic interventions are often available. (moderate individual risk, low community risk) e.g: Herpes virus, streptococcus.
Risk Group 3(RG-3):
Pathogens are associated with serious human or animal disease but do not ordinarily spread from one infected individual to another for which preventive or therapeutic intervention may be available. (high individual risk, low community risk) eg: Black plague.
Risk Group 4(RG-4):
Pathogens are associated with the serious human, or animal disease can be readily transmitted from one individual to another, directly or indirectly for which preventive or therapeutic intervention is not available. (high individual & community risk) E.g: SARS Covid -19, Ebola virus.
It can be concluded that the level of hazards associated with risk groups is lowest in RG1 and highest in RG4. If there is the use of the microorganisms belonging to risk group 4 means that extensive security is in place. It is not only due to the virulence of that pathogen but also due to their potential for use in bioterrorism.
Biosafety levels are base on the composite of design features, equipment, containment facilities, operational procedures, and construction, etc. that required for working with microorganisms from various risk groups mentioned.
There are four biosafety or pathogen/protection levels to protect against the pathogens including bacteria, viruses, parasites, prions, rickettsiae, etc. Protection from infectious biological agents must be taken into consideration and ensured for laboratory personnel, local community and the environment. Therefore at any biosafety level, there are strict requirements for laboratory design, personal protective equipment and biosafety equipment to be used. We can relate risk groups to the biosafety level but can not equate the levels with groups.
For example, procedure with an infectious biological agent may be conducted under the BSL-2 conditions, but another procedure with the same infectious biological agent maybe that increases the risk to laboratory personnel or environments such as the creation of droplets or aerosols, larger-scale production requires the work to be conducted under the BSL-3 conditions.
Biosafety level 1(BSL-1)
1. BSL-1 labs are known to use to study infectious biological agents, they do not cause diseases in healthy adults and animals.
2. It causes minimal hazard to laboratory personnel, local and environment.
3. BSL-1 laboratories include an easily cleaned working surface.
Biosafety level 2(BSL-2)
1. BSL-2 laboratories are used to study moderate risk infectious biological agents or pathogens that pose risk when accidentally inhaled, swallowed.
2. Supervision by the scientist with training in microbiology or related field.
3. There should be open bench plus biological safety cabinet for potential aerosols formed during the study of infectious microorganisms.
Biosafety level 3(BSL-3)
1. BSL-3 laboratories are used to study a serious and potentially lethal disease that enters through an inhalation route.
2. For this there should be a drafted laboratory-specific biosafety manual includes how to operate and all safety requirements.
3. Laboratory practices should as Level 2 plus special clothing, controlled access, directional airflow.
1. BSL-4 is the highest level of biosafety precautions, and this is appropriate for work with those infectious biological agents that cause severe to fatal disease in human and animals for which there is no available vaccine and treatment.
2. There should be class III BSC, or positive pressure suits in conjunction with Class II BSCs, double-ended autoclave (through the wall), filtered air safety equipment.
The assignment of an agent to a biosafety level for laboratory work must be based on a risk assessment, and these factors can be taken into account:
● Pathogenicity of the microorganisms.
● Mode of transmission and the host range of microorganisms.
● Local availability of effective preventive measures.
● Local availability of effective preventive treatments.
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3. Laboratory biosafety manual. (2004). Retrieved from WHO website
4. Biosafety level. (2020). Retrieved from phe.hov