Agent Classification

The principal hazardous characteristics of an agent are: its capability to infect and cause disease in a susceptible human or animal host, its virulence as measured by the severity of disease, and the availability of preventive measures and effective treatments for the disease. The World Health Organization (WHO) has recommended an agent risk group classification for laboratory use that describes four general risk groups based on these principal characteristics and the route of transmission of the natural disease. The four groups address the risk to both the laboratory worker and the community. The NIH Guidelines established a comparable classification and assigned human etiological agents into four risk groups on the basis of hazard The descriptions of the WHO and NIH risk group classifications are presented below. They correlate with but do not equate to biosafety levels. A risk assessment will determine the degree of correlation between an agent’s risk group classification and biosafety level.

RISK GROUP CLASSIFICATION	NIH GUIDELIENS FOR RESEARCH INVOLVING RECOMBINANT DNA MOLECULES 2002	WORLD HEALTH ORGANIZATION LABORATORY BIOSAFETY MANUAL 3RD EDITION 2004
Risk Group 1	Agents which are not associated with disease in healthy adult humans.	(No or low individual and community risk) A microorganism that is unlikely to cause human or animal disease.
Risk Group 2	Agents which are associated with human disease which is rarely serious and for which preventative or therapeutic interventions are *often* available.	(Moderate individual risk; low community risk) A pathogen that can cause human or animal disease but is unlikely to be a serious hazard to laboratory workers, the community, livestock or the environment. Laboratory exposures may cause serious infection, but effective treatment and preventative measures are available and the risk of spread of infection is limited.
Risk Group 3	Agents which are associated with serious or lethal human disease for which preventative or therapeutic interventions *may be* available (high individual risk but low community risk).	(High individual risk; low community risk) A pathogen that usually causes serious human or animal disease but does not ordinarily spread from one infected individual to another. Effective treatment and preventative measures are available.
Risk Group 4	Agents which are likely to cause serious or lethal human disease for which preventative or therapeutic interventions are *not usually* available (high individual risk and high community risk).	High individual risk; high community risk) A pathogen that usually causes serious human or animal disease and that can be readily transmitted from one individual to another, directly or indirectly. Effective treatment and preventative measures are usually not available.

Summary of Recommended Biosafety Levels for Infectious Agents

BSL	AGENTS	PRACTICES	PRIMARY BARRIERS & SAFETY EQUIPMENT	FACILITIES (SECONDARY BARRIERS)
1	Not known to consistently cause disease in healthy adults	Standard Microbiological Practices	None required	Open bench and sink required
2	Agents associated with human disease Routes of transmission include percutaneous injury, ingestion, mucous membrane exposure	BSL-1 practices plus: Limited access Biohazard warning sign “Sharps” precautions Biosafety manual defining any needed waste decontamination or medical surveillance policies	Primary barriers: Class I or II BSCs or other physical containment devices used for all manipulations of agents that cause splashes or aerosols of infectious materials PPE:Laboratory coats, gloves, face protection as needed	BSL-1 plus: Autoclave available
3	Indigenous or exotic agents with potential for aerosol transmission Disease may have serious or lethal consequences	BSL-2 practice plus: Controlled access Decontamination of all waste Decontamination of laboratory clothing before laundering Baseline serum	Primary barriers: Class I or II BSCs or other physical containment devices used for all open manipulations of agents PPE: Protective laboratory clothing; gloves; respiratory protection as needed	BSL-2 plus: Physical separation from access corridors Self-closing, double-door access Exhaust air not recirculated Negative airflow into laboratory
4	Dangerous/exotic agents which pose high risk of life-threatening disease Aerosol-transitted laboratory infections have occurred; or related agents with unknown risk of transmission	BSL-3 practices plus: Clothing change before entering Shower on exit All material decontaminated on exit from facility	Primary barriers: All procedures conducted in Class III BSCs or Class I or II BSCs in combination with full-body, air-supplied, positive pressure personnel suit	BSL-3 plus: Separate building or isolated zone Dedicated supply and exhaust, vacuum, and decontamination systems

Summary of Recommended Biosafety Levels for Activities in which Experimentally or Naturally Infected Vertebrate Animals are Used

ABSL	AGENTS	PRACTICES	PRIMARY BARRIERS & SAFETY EQUIPMENT	FACILITIES (SECONDARY BARRIERS
1	Not known to consistently cause disease in healthy adults	Standard animal care and management practices, including appropriate medical surveillance programs	As required for normal care of each species	Standard animal facility: No recirculation of exhaust air Directional air flow Recommended Hand washing sink is available
2	Associated with human disease Hazards: percutaneous exposure, ingestion, mucous membrane exposure	ABSL-1 practice plus: Limited access Biohazard warning signs “Sharps” precautions Biosafety manual Decontamination of all infectious wastes and of animal cages prior to washing	ABSL-1 equipment plus primary barriers: Containment equipment appropriate for animal species PPE: Laboratory coats, gloves, face and respiratory protection as needed	ABSL-1 plus: Autoclave available Hand washing sink available Mechanical cage washer recommended
3	Indigenous or exotic agents with potential for aerosol transmission Disease may have serious health effects	ABSL-2 practice plus: Controlled access Decontamination of clothing before Laundering Cages decontaminated before bedding removed Disinfectant foot bath as needed	ABSL-2 equipment plus: Containment equipment for housing animals and cage dumping activities Class I, II or III BSCs available for manipulative procedures (inoculation, necropsy) that may create infectious aerosols. PPEs: Appropriate respiratoryprotection	ABSL-2 facility plus: Physical separation from access Corridors Self-closing, double-door access Sealed penetrations Sealed windows Autoclave available in facility
4	Dangerous/exotic agents that pose high risk of life threatening disease Aerosol transmission, or related agents with unknown risk of transmission	ABSL-3 practices plus: Entrance through change room where personal clothing is removed and laboratory clothing is put on; shower on exiting All wastes are decontaminated before removal from the facility	ABSL-3 equipment plus: Maximum containment equipment (i.e., Class III BSC or partial containment equipment in combination with full body, air supplied positive-pressure personnel suit) used for all procedures and activities	ABSL-3 facility plus: Separate building or isolated zone Dedicated supply and exhaust, vacuum and decontamination systems Other requirements outlined in the text

Recommended Biosafety levels for plants can be found in the NIH Guidelines for Research Involving Recombinant DNA Molecules Appendix P
http://www4.od.nih.gov/oba/rac/guidelines_02/NIH_Gdlnes_lnk_2002z.pdf
Agricultural Pathogen Biosafety guidance can be found in the BMBL 5th edition Appendix D
http://www.cdc.gov/od/ohs/biosfty/bmbl5/Appendix%20D%20%20%20Agriculture%20Pathogen%20Biosafety.pdf