Risk Groups and Biosafety Levels
Risk Groups
Biohazardous agents are classified into Risk Groups by regulating agencies such as the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health (NIH). The classification of many biohazardous agents can be found in the CDC Biosafety in Microbiological and Biomedical Laboratories (BMBL), the NIH Guidelines for Research Involving Recombinant DNA Molecules (NIH Guide), or from the American Biological Safety Association (ABSA) Risk Group Database. The risks are generically defined as follows:
| Risk Group | Definition |
|---|---|
| RG 1 | Well characterized agents that are not known to cause disease in healthy adults, or agents that present a minimal risk to the environment. |
| RG 2 | Agents that are known to cause disease in healthy adults which is rarely serious and for which prevention or treatment options are available, or agents that pose a moderate risk to the environment. |
| RG 3 | Agents that are known to cause serious or fatal disease, particularly by the inhalation route, and for which there may be preventive or treatment options available, or agents that pose a high risk to the environment. |
| RG 4 | Agents that are likely to cause serious or fatal disease for which prevention or treatment options are not usually available, or those agents that pose a serious threat to the environment. |
Biosafety Levels
The same regulatory groups have created Biosafety Levels (BSL) that define a set of laboratory practices, facilities and equipment that are appropriate to contain and safely work with the different Risk Groups. The determination of appropriate biosafety level for a project or for a laboratory is made by evaluating the agents in use and the specific procedures and experiments being performed with those agents. Unless specified by regulation, the determination of Biosafety Level for a project or laboratory is made by the Ohio University IBC in conjunction with the PI.
In general, the Biosafety Level will be the same as the highest Risk Group for the agents involved. The table on the following page gives an overview of Biosafety Levels; it is taken from the CDC BMBL 6th Edition, 2020. For a detailed description of Biosafety Levels, refer to the CDC BMBL.
| BSL | Agents | Special Practices* | Primary Barriers and PPE* | Facilities (Secondary Barriers)* |
|---|---|---|---|---|
| 1 | Well-characterized agents not known to consistently cause disease in immunocompetent adult humans and present minimal potential hazard to laboratory personnel and the environment (RG1) | Standard Microbiological Practices | No primary barriers required; protective laboratory clothing; protective face, eyewear, as needed | Laboratory doors; sink for handwashing; laboratory bench; windows fitted with screens; lighting adequate for all activities |
| 2 | Agents associated with human disease and pose moderate hazards to personnel and the environment (RG2) | Limited access; occupational medical services including medical evaluation, surveillance, and treatment, as appropriate; all procedures that may generate an aerosol or splash conducted in a BSC; decontamination process needed for laboratory equipment | BSCs or other primary containment device used for manipulations of agents that may cause splashes or aerosols; protective laboratory clothing; other PPE, including respiratory protection, as needed | Self-closing doors; sink located near exit; windows sealed or fitted with screens; autoclave available |
| 3 | Indigenous or exotic agents; may cause serious or potentially lethal disease through the inhalation route of exposure (RG3) | Access limited to personnel with need to enter; viable material removed from laboratory in primary and secondary containers; opened only in BSL-3 or ABSL 3 laboratories; all procedures with infectious materials performed in a BSC | BSCs for all procedures with viable agents; solid front gowns, scrubs, or coveralls; two pairs of gloves, when appropriate; protective eyewear, respiratory protection, as needed | Physical separation from access corridors; access through two consecutive self closing doors; hands-free sink near exit; windows are sealed; ducted air ventilation system with negative airflow into laboratory; autoclave available, preferably in laboratory |
| 4 | Dangerous and exotic agents that pose high individual risk of aerosol transmitted laboratory infections and life-threatening disease that are frequently fatal, for which there are no vaccines or treatments; and related agents with unknown risk of transmission (RG4) | Clothing change before entry; daily inspections of essential containment and life support systems; all wastes decontaminated prior to removal from laboratory; shower on exit | BSCs for all procedures with viable agents; solid front gowns, scrubs, or coverallsa; glovesa; full-body, air supplied, positive pressure suitb a. Applies to Cabinet Laboratory b. Applies to Suit Laboratory | Entry sequence; entry through airlock with airtight doorsb; walls, floors, ceilings form sealed internal shell; dedicated, non-recirculating ventilation system required; double door, pass-through autoclave required b. Applies to Suit Laboratory |
* Each successive BSL contains the criteria of the preceding level(s).