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Safe Laboratory Practices
Laboratory Biosafety Level Criteria
Table1: Summary of  Recommended Biosafety  Levels for Infectious Agents
Table1a: Summary of Vertebrate Animal Biosafety Levels (ABSL)
Biological Emergencies
Biosafety Cabinets (BSC's)
Types of BSC's
Comparison of BSC's Characteristics
Selection of a BSC Through Risk Assessment
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Table 1a: Summary of Recommended Biosafety Levels for Activities in Which Experimentally or Naturally Infected Vertebrate Animals Are Used

BSL Agents Practices Safety Equipment (Primary Barriers) Facilities (Secondary Barriers)
1 Not known to consistently cause disease in healthy human 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 recommended

2 Associated with human disease. Hazard: percutaneous exposure, ingestion, mucous membrane exposure. ABSL-1 practices 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; PPES: laboratory coats, gloves, face and respiratory protection as needed. ABSL-1 facility plus:

Autoclave available

Hand washing sink available in the animal room.

Mechanical cage washer used

3 Indigenous or exotic agents with potential for aerosol transmission; disease may have serious health effects. ABSL-2 practices 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 or II BSCs available for manipulative procedures (inoculation, necropsy) that may create infectious aerosols. PPEs: appropriate respiratory protection

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

Reproduced from "Biosafety in Microbiological and Biomedical Laboratories, BMBL 4th Edition" with permission from the Center for Disease Control (CDC).

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