Recommended Biosafety Levels for Infectious Agents and Infected Animals

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  • Topic: Biosafety level, Biology, Biocontainment
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IPR, BIOSAFETY & BIOETHICS

RECOMMENDED BIOSAFETY LEVELS FOR INFECTIOUS AGENTS AND INFECTED ANIMALS

Submitted By
PARIDHI SINGHAL
MT/BT/1001/2010
Department of Biotechnology
RECOMMENDED BIOSAFETY LEVELS FOR INFECTIOUS AGENTS AND INFECTED ANIMALS

INTRODUCTION

CDC describes four biosafety levels (BSLs) which consist of combinations of laboratory practices and techniques, safety equipment, and laboratory facilities.  Each combination is specifically appropriate for the operations performed, the documented or suspected routes of transmission of the infectious agents, and for the laboratory function or activity.  The recommended biosafety level for an organism represents the conditions under which the agent can be ordinarily handled safely.  When specific information is available to suggest that virulence, pathogenicity, antibiotic resistance patterns, vaccine and treatment availability, or other factors are significantly altered, more (or less) stringent practices may be specified. 

Biological Safety Level 1 (BSL-1) -- is appropriate for work done with defined and characterized strains of viable microorganisms not known to cause disease in healthy adult humans.  It represents a basic level of containment that relies on standard microbiological practices with no special primary or secondary barriers recommended, other than a sink for hand washing.  

Biological Safety Level 2 (BSL-2) -- is applicable to work done with a broad spectrum of indigenous moderate-risk agents present in the community and associated with human disease of varying severity.  Agents can be used safely on the open bench, provided the potential for producing splashes or aerosols is low.  Primary hazards to personnel working with these agents relate to accidental percutaneous or mucous membrane exposures or ingestion of infectious materials.  Procedures with high aerosol or splash potential must be conducted in primary containment equipment such as biosafety cabinets.  Primary barriers such as splash shields, face protection, gowns and gloves should be used as appropriate.  Secondary barriers such as hand washing and waste decontamination facilities must be available.

Biological Safety Level 3 (BSL-3) -- is applicable to work done with indigenous or exotic agents with a potential for respiratory transmission and which may cause serious and potentially lethal infection.  Primary hazards to personnel working with these agents (i.e., Mycobacterium tuberculosis, St. Louis encephalitis virus and Coxiella burnetii) include auto-inoculation, ingestion and exposure to infectious aerosols.  Greater emphasis is placed on primary and secondary barriers to protect personnel in adjoining areas, the community and the environment from exposure to infectious aerosols.  For example, all laboratory manipulations should be performed in a biological safety cabinet or other enclosed equipment.  Secondary barriers include controlled access to the laboratory and a specialized ventilation system that minimizes the release of infectious aerosols from the laboratory. 

Biological Safety Level 4 (BSL-4) -- is applicable for work with dangerous and exotic agents that pose a high individual risk of life-threatening disease, which may be transmitted via the aerosol route and for which there is no available vaccine or therapy. 

RECOMMENDED BIOSAFETY LEVELS FOR INFECTIOUS AGENTS

Level| Agents| Practices| Safety Equipment (Primary Barriers)| Facilities (Secondary Barriers)| 1| Not known to consistently cause disease in healthy adults.| Standard Microbiological Practices.| None Required.| Laboratory bench and sink required.| 2| Agents associated with human diseaseRoutes of transmission include percutaneous injury, ingestion, mucous membrane exposure| BSL - 1 practice plus: *  Limited access;

*  Biohazard warning signs;
*  "Sharps" precautions;
*  Biosafety manual defining any needed waste decontamination or medical surveillance policies.|...
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