Biosafety levels With their Primary and Secondary Barriers.

Written by SouravBio · 4 minutes read >

Biosafety Definition

Biosafety defines as the application of safety precautions which reduces a laboratorians risk of exposure to potentially infectious material and limits contamination of the work environment and ultimately the community.

Why we need Biosafety?

We need biosafety because of;

  • to protect the laboratory worker and the surrounding environment from infectious hazards.
  • Accidental threads to laboratorians and the environment.
  • To have adherence to safety regulations while dealing with highly infectious agents.

Different Biosafety Level

Biosafety levels are defined by how much risk is involved in working with particular pathogens. The Conversation, CC BY-ND

Biosafety Level is also known as pathogen/protection level, it is referred to a set of biocontainment precautions that are required for the isolation of dangerous biological agents within an enclosed laboratory facility. 

There are different biosafety levels which are ranging from the lowest biosafety level 1 (BSL-1) to the highest at level 4 (BSL-4). Sometimes these are also known as the  P1 through P4 (for pathogen or protection level).

There are four Biosafety level such as;

Biosafety level 1 (BSL 1)

The biosafety level 1 deals with those well-characterized agents which pose minimal potential hazard to laboratory workers and the environment.

Biosafety levels 1
Biosafety levels 1 | Image Source: Laboratory Safety and Management

Precautions and Procedures of Biosafety Level 1 (BSL 1)

  • Required good laboratory practices.
  • Required Personal protective equipment.
  • Open bench sinks.
  • Worker must wash their hands after leaving the lab and before entering the lab.
  • The door must be closed during the working with infectious agents.
  • During the Work on lab required limit access to the lab workspace.
  • Don’t smoke, eat, drink, or store food within the laboratory.
  • Standard open laboratory benches are allowed biosafety cabinets are not required.
  • Decontaminate the potentially infectious material before disposing, with either by adding bleach or isopropanol or by packaging for decontamination elsewhere.
  • Daily Sterilize of decontaminate the workplace after work has done.
  • Must use mechanical pipetting and avoid mouth pipetting.

Safety Equipements or Primary barrier

  • Personal Protective Equipments such as laboratory coats, gloves, and face protection.

Agents of Biosafety Level 1 (BSL 1)

E. coli K-12, Bacillus subtilis, Adenoasociated viruses 1-4, T4 bacteriophages, Saccharomyces cerevisiae, Rhizopus stolonifer, Candida albicans, Pseudomonas, Infectious canine hepatitis,  Transgenic Plants, Plasmids, Fungi, Mold, Yeast.

Biosafety level 2 (BSL 2)

Biosafety level 2 (BSL 2) is used to study the moderate-risk infectious agents or toxins to personnel and the environment. These agents will be dangerous if they accidentally inhaled, swallowed, or exposed to the skin.

Biosafety levels 2
Biosafety levels 2 | Image Source: research.utexas.edu | Graphics kindly provided by CUH2A, Princeton, NJ, USA WHO Biosafety Manual 3rd ed., 2004

Safety Equipements or Primary barrier

  • Required class I and class II biosafety cabinets.
  • Personal Protective Equipments such as laboratory coats, gloves, and face protection.

Facilities or Secondary Barries

  • Include all Biosafety level 1 precautions.
  • Limited access to the lab.
  • Required daily de-contamination after work done.
  • Use mechanical pipetting.
  • Wear lab coat, gloves, during the experiment.
  • A biohazard warning poster is mandatory at the entrance door of lab.
  • Tc room – negative airflow.
  • Full body sterilization before entering the lab and after exit from the lab.

Agents of Biosafety Level 2 (BSL 2)

S. aureus, Bordetella pertussis, Corynebacterium diphthriae, Other E coli, Nisseria gonorrhoea, Streptococcus pyogenes, Vibrio cholerae, Klesiella spp., Proteus, Serratia marcescens, Salmonella, L. monocytogenes  Rabies,  Hepatitis A, B, C , Cryptococcus neoformans, Most parasitic agents, Human or Primate Cells, Herpes Simplex Virus, Replication Incompetent Attenuated Human Immunodeficiency Virus, Patient specimens.

Biosafety level 3 (BSL 3)

Biosafety level 3 (BSL 3) is used to study those organisms which can cause serious and potentially lethal disease via the inhalation route.

Biosafety levels 3
Biosafety levels 3 | Image Source: research.utexas.edu | Graphics kindly provided by CUH2A, Princeton, NJ, USA WHO Biosafety Manual 3rd ed., 2004

Safety Equipements or Primary barrier

  • Required class I and class II biosafety cabinets.
  • Personal Protective Equipments such as laboratory coats, gloves, and face protection.

Facilities or Secondary Barries

  • Include all Biosafety level 2 precautions.
  • Biohazard sign poster on each lab equipments.
  • Bench top work not allowed.
  • The exhaust air from the laboratory room is discharged to the outdoor.
  • The laboratory ventilation system should be balanced to provide directional airflow to the room.
  • Self-closing double doors.
  • The corridor should be sperate from the lab.
  • Air pumped into the laboratory not re-circulated into the building.

Agents of Biosafety Level 3 (BSL 3)

Francisella tularensis, Mycobacterium tuberculosis, Chlamydia psittaci, Venezuelan equine encephalitis virus, Eastern equine encephalitis virus, SARS-CoV-1, SARS-CoV-2, MERS-CoV, Coxiella burnetii, Rift Valley fever virus, Rickettsia rickettsii, several species of Brucella, chikungunya, yellow fever virus, West Nile virus, Yersinia pestis.

Biosafety level 4 (BSL 4)

Biosafety level 4 (BSL 4) is used to study those microorganisms are aerosol-transmitted and can cause severe to fatal disease in humans for which there are no vaccines or treatments.

Biosafety levels 4
Biosafety levels 4 | Image Source: CDC

Safety Equipements or Primary barrier

  • Requires Biological Safety cabinets (I, II, III).
  • Full-body air supplied, positive pressure personal suite.

Facilities or Secondary Barries

  • Must have a dedicated air and exhaust system.
  • Decontamination of laboratory after exiting.
  • Lab should be in a separate building.
  • No window.
  • Required maximum containment facilities.
  • Should follow all BSL-3/ABSL -3 practice.
  • Full body sterilization before entering the lab and after exit from the lab.
  • The biowaste must be decontaminated in a proper way before dispose.

Agents of Biosafety Level 4 (BSL 4)

Ebola Hemorrhagic Fever Virus, Marburg Virus, Lassa Fever Virus, Machupo virus, Crimean congo Haemorrhagic viruses, Bolivian and Argentine, Haemorrhagic fever viruses, Some encephalitis viruses, Herpesvirus simiae. (No bacterial agents, No fungal agents, No parasitic agents)

Primary Barrier: Primary barrier refers to all lab equipments such as Biological safety cabinet, fume hood, glove box, animal housing, centrifuge, fermenter.

Secondary Barrier:  Secondary Barrier barrier refers to the structure surrounding the primary barrier such as Rooms, building, Basic laboratory, Containment laboratory.

Further Reading

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Writer and Founder of Microbiologynote.com. I am from India and my main purpose is to provide you a strong understanding of Microbiology. Microbiologynote.com shares notes related to different branches of microbiology.

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