A
biosafety level (BSL), or pathogen / protection level, is a set of
bio-containment precautions necessary to isolate hazardous biological agents in
a closed laboratory facility. Containment levels range from the lowest
biosafety level 1 (BSL-1) to the highest at level 4 (BSL-4).
These
levels, which are classified from one to four, are selected based on the agents
or organisms that are studied or that work in any laboratory environment. For
example, a basic laboratory environment specializing in the search for
non-lethal agents that pose a minimal potential threat to laboratory workers
and the environment are generally considered to be BSL-1, the lowest biosafety
laboratory level. A specialized research laboratory dealing with potentially
lethal infectious agents such as Ebola would be designated BSL-4, the highest
and most rigorous level.
The
Centers for Disease Control and Prevention (CDC) sets BSL laboratory levels as
a way to visualize specific controls for the containment of microbes and
biological agents. Each BSL laboratory level builds on the previous level, thus
creating layer by layer of constraints and barriers. These laboratory levels
are determined by the following
- Risks associated with containment.
- Severity of the infection
- Transmissibility
- Nature of the work done.
- Origin of the microbe.
- Agent in question
- Route of exposure
The
reason why biosafety levels are so important is because they dictate the type
of work practices allowed in a laboratory. Furthermore, they greatly influence
the general design of the installation in question, as well as the type of
specialized safety equipment used in it.
Below is
an explanation of each level of biosafety: what they mean and how they differ
in safety measures and best practices.
Table
2. Relation of risk groups to biosafety levels, practices and equipment
|
RISK GROUP |
BIOSAFETY LEVEL |
LABORATORY TYPE |
LABORATORY PRACTICES |
SAFETY EQUIPMENT |
|
1 |
Basic - Biosafety Level
1 |
Basic teaching,
research |
GMT |
None;
open bench work |
|
2 |
Basic
– Biosafety Level 2 |
Primary
Health Service; Diagnostic Service; Research |
GMT
plus protective clothing, biohazard sign |
Open
bench plus BSC for potential aerosols |
|
3 |
Containment
– Biosafety Level 3 |
Special
diagnostic services; research |
As
Level 2 plus special clothing, controlled access, directional airflow |
BSC
and/or other primary devices for all
activities |
|
4 |
Maximum
containment – biosafety Level 4 |
Dangerous
pathogen units |
As
Level 3 plus airlock entry, shower exit, special waste disposal |
Class
III BSC, or positive pressure suits in conjunction with Class II BSCs, double
ended autoclave (through the wall), filtered air |
|
BSC,
biological safety cabinet; GMT, good microbiological techniques |
||||
BSL–1
Being the lowest of the four,
biosafety level 1 applies to laboratory settings where staff work with low-risk
microbes that pose little or no threat of infection in healthy adults. An
example of a microbe that is normally processed on a BSL-1 is a non-pathogenic
strain of E. coli.
This laboratory environment
generally consists of research conducted in banks without the use of special
contaminating equipment. A BSL-1 laboratory, which is not required to isolate
itself from surrounding structures, hosts activities that require only standard
microbial practices, such as:
- Mechanical pipetting only (front pipetting is not allowed)
- Safe handling of sharp objects
- Avoid splashing or splashing.
- Daily decontamination of all work surfaces at the end of the work.
- To wash hands
- Prohibition of food, drinks and smokers' materials in the laboratory.
- Personal protective equipment, such as; eye protection, gloves and lab coat or laboratory dress
- Biohazard signs
BSL-1 labs also require immediate
decontamination after spillage. The materials for infections are also
decontaminated before disposal, generally by using an autoclave.
This level of biosafety covers
laboratories that work with agents associated with human diseases (i.e.
pathogenic or infectious organisms) that present a moderate health risk.
Examples of agents commonly used in a BSL-2 include equine encephalitis virus and
HIV, as well as Staphylococcus aureus
(staphylococcal infections).
BSL-2 labs maintain the same
standard microbial practices as BSL-1 labs, but also include improved measures
due to the potential risk of the above microbes. Staff working in BSL-2 laboratories
should be even more careful to prevent injuries such as cuts and other skin
gaps, as well as ingestion and exposure to mucous membranes.
In addition to the expectations of
BSL 1, the following practices are required in a BSL 2 laboratory environment:
- Appropriate Personal Protective Equipment (PPE), including lab coats and gloves, must be worn. If necessary, eye protection and visors can also be used.
- All procedures that can cause aerosol or splash infection are performed inside a biological safety cabinet (BSC).
- An autoclave or alternative decontamination method is available for proper disposal.
- The laboratory has self-closing and lockable doors.
- An eye wash and hand wash station must be available.
- Biohazard warning signs
Access to a BSL-2 laboratory is much more restrictive than a BSL-1 laboratory. External personnel, or those at greatest risk of contamination, often cannot enter after work is finished.
BSL-3
Again, based on the two previous
levels of biosafety, a BSL-3 laboratory generally includes work on microbes
that are indigenous or exotic and which can cause serious or life-threatening
inhalation diseases. Examples of microbes that have been processed in a BSL-3
include; yellow fever, West Nile virus and bacteria that cause tuberculosis.
Microbes are so serious that work is
often strictly controlled and recorded with the appropriate government
agencies. Laboratory staffs are also under medical supervision and can receive
vaccines for the microbes they work with.
Common requirements in a BSL-3
laboratory include:
- Standard
personal protective equipment must be worn and respirators may be required
- Front
wrap-around clothes, cleaning suits or coveralls are often required
- All
work with microbes must be done within an appropriate BSC
- Access
to the sink and sink are available near the exit.
- Directional
air flow sustained to suck air in the laboratory from clean areas to
potentially contaminated areas (the exhaust air cannot be recirculated)
- A series of self-closing doors with remote access from the general corridors of the building.
- Access to a BSL-3 laboratory is always limited and controlled.
BSL-4
BSL-4 labs are rare. However, some exist in a limited number
of places in the United States and around the world. As a maximum level of
biological safety, a BSL-4 laboratory plans to work with highly dangerous and
exotic microbes. The infections caused by these types of microbes are often
fatal and come without treatment or vaccines. Two examples of such microbes
include the Ebola and Marburg viruses.
In addition to BSL-3 considerations, BSL-4 labs have the
following containment requirements:
- Staff must change clothes before entering, take a shower after leaving
- Decontamination of all materials before leaving.
- Personnel must wear adequate personal protective equipment from the above BSL levels, as well as a full suit, with air supply and positive pressure.
- A class III biological safety cabinet
A BSL-4 laboratory is extremely isolated, often located in a
separate building or in an isolated and reserved area of the building. The
laboratory also has dedicated supply and exhaust air, as well as suction lines
and decontamination systems.
Knowing the difference in bio-safety laboratory levels and
the corresponding safety requirements is a must for anyone working with
microbes in a laboratory environment.
List Of BSL-4 Lab in INDIA
|
Laboratory
Name |
Area |
Established |
Description |
|
High Security Animal Disease
Laboratory (HSADL) |
1998 |
This facility deals especially to zoonotic organisms and emerging infectious disease threats |
|
|
2009 |
National BSL-4 Containment Facility for Human Infectious Diseases. |
||
|
2012 |
India's first BSL4 lab and the most advanced. |
Reference
- "Bio-containment Laboratory". National Institute of High Security Animal Diseases, India. Archived from the original on 19 March 2016. Retrieved 20 April 2016.
- "National Microbiology Laboratory (NML) Overview". Public Health Agency of Canada. Archived from the original on 21 March 2016. Retrieved 8 April 2016.
- "NIV Prune lab gets BSL-4". The Hindu. Archived from the original on 16 August 2017. Retrieved 24 April 2016.
- "Stone laid for stem cell research lab in Hyderabad". The Hindu. Archived from the original on 16 January 2016. Retrieved 25 April 2016.
- https://ncdc.gov.in/WriteReadData/l892s/File608.pdf
- https://www.who.int/csr/resources/publications/biosafety/Biosafety7.pdf
Precisely explained about biosafty..
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