One of the most important aspects of biosafety is assessing the risk associated with the laboratory manipulations of the agent or organism under investigation. Risk assessments should be performed by individuals most familiar with the specific characteristics of the agent/organism being considered for use, the equipment and procedures to be employed, animal models that may be used and the containment equipment and facilities available. The laboratory director or PI is responsible for ensuring that adequate risk assessments are performed and that appropriate equipment and facilities are available to support the work being proposed. One of the most helpful tools available for performing a risk assessment is the listing of RG (risk groups) for microbiological agents. Table 1 below describes how microorganisms are classified into risk groups; the NIH Guidelines and the BMBL lists individual microorganisms according to their assigned RG/Biosafety Level designation.
Table 1 Classification of infective microorganisms by risk group (RG)
Risk Group 1:
Microorganisms not associated with human or animal disease.
- No or very low individual and community risk.
Risk Group 2:
Microorganisms associated with human or animal disease which is rarely serious and for which preventative or therapeutic interventions are often available.
- Moderate individual risk, low community risk.
Risk Group 3:
Microorganisms associated with serious or lethal human or animal disease for which preventative or therapeutic interventions may be available.
- High individual risk, low community risk.
Risk Group 4:
Microorganisms likely to cause serious or lethal disease or which preventative or therapeutic interventions are not usually available.
- High individual risk, high community risk.
However, simple reference to the risk group for a particular agent is insufficient in the conduct of a risk assessment. Other factors that should be considered, as appropriate, include:
- pathogenicity of the agent and infectious dose;
- routes of infection (parenteral, airborne, ingestion);
- stability of the agent in the environment;
- presence of a suitable host (human or animal);
- laboratory activity planned (concentration, sonication, aerosolization, centrifugation, large volumes, etc.);
- any genetic manipulation of the organism that may extend the host range of the agent or alter the agent’s sensitivity to known, effective treatment regimens; and
- local availability of effective prophylaxis or therapeutic interventions.
On the basis of the information ascertained during the risk assessment, a BSL (biosafety level) can be assigned to the planned work and appropriate personal protective equipment selected.