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Risk Assessment: Agent Hazards:
- Capability to infect and cause disease in a susceptible host
- Virulence as measured by the severity of disease
- Availability of preventive measures and effective treatments for the disease
- Probable routes of transmission of laboratory infection
The predominant routes of transmission in the laboratory include mucous membrane exposure, parenteral inoculation, ingestion and inhalation of infectious aerosols.
- Infective dose
- Stability in the environment
- Host range
- Its endemic nature
- Reports of laboratory acquired infections
- Origin of the agent
Classification of Infectious Agents on the Basis of Hazard (Risk Groups)
Risk groups (RG) are a method used by the World Health Organization (WHO) and by the National Institutes of Health (NIH) to classify human etiological agents based on hazard to both the individual and to the community. There are four risk groups. These correlate to but are not equivalent to biosafety levels. Determining the risk group of a biological agent can be part of the biosafety risk assessment and helps in assigning the correct biosafety level for containment. In general, RG-2 agents are handled at BSL- 2, and RG-3 agents at BSL-3. However, the use of certain RG-2 agents in large quantities might require BSL-3 conditions, while some RG-3 agents may be safely manipulated at a BSL-2 under certain conditions.
Table 1: Basis for the Classification of Biohazardous Agents by Risk Group
Risk Group |
Risk to the individual and the community |
Risk Group 1
(RG-1)
|
Agents that are not associated with disease in healthy adult humans (no or low individual and community risk). |
Risk Group 2
(RG-2)
|
Agents that are associated with human disease which are rarely serious and for which preventive or therapeutic interventions are often available (moderate individual risk but low community risk).
|
Risk Group 3
(RG-3)
|
Agents that are associated with serious or lethal human disease for which preventive or therapeutic interventions may be available (high individual risk but low community risk).
|
Risk Group 4
(RG-4) |
Agents that are likely to cause serious or lethal human disease for which preventive or therapeutic interventions are not usually available (high individual risk and high community risk) |
Examples of RG-1 agents include microorganisms like Escherichia coli-K12 or Saccharomyces cerevisiae. A list of Risk Group 2, 3 and 4 agents can be found in Appendix D. It is important to note however, that no list is all inclusive. Also, those agents not listed in RG-2, RG-3 or RG-4 are not automatically classified in RG-1. Those unlisted agents need to be subjected to a risk assessment based on the known and potential properties of the agents.
Hazards of Genetically-Modified Agents
When conducting a risk assessment of genetically modified agents, consideration of the same factors used in risk assessment of the wild-type organism should be done. However, it is important to address the possibility that the genetic modification could alter (i.e., increase or decrease) the pathogenicity of the agent or affect its susceptibility to antibiotics or other treatments. Sometimes, important information may not be available for a newly engineered agent and the risk assessment may be difficult or incomplete. In these cases, due diligence should be practiced and the biosafety level assignment should be made conservatively. Once more information is available another risk assessment should be completed.
Hazards of Cell Cultures
Human and animal cells and tissues have the potential to harbor latent infectious agents and personnel who handle these materials are at risk for possible exposure. For additional information and requirements for working with human cell cultures please refer to the MSU Exposure Control Plan and to the following section of this manual: Guidelines for Working with Tissue Culture/Cell Lines .
Risk Assessment: Laboratory Procedure Hazards
Biosafety
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