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Biosafety Levels Precautions so people researching or
trying to identify organisms do not become infected
While handling or testing clinical specimens, workers could accidentally infect themselves or coworkers
Labs must adhere to very specific safety regulations to work with organisms that pose a threat to human health
Biosafety Levels Regulations outline precautions, special
practices, decontamination procedures Labs divided into 4 biosafety levels;
protective practices increase with each Biosafety Level 1 labs - work with least
dangerous agents, require fewest precautions
Biosafety Level 4 labs - have strictest methods because dealing with agents that are most dangerous to human health
About this Information… Information summarized here should
not be used to establish laboratory safety protocols
Complete information and recommendations can be found in Biosafety in Microbiological and Biomedical Laboratories 5th Edition at http://www.cdc.gov/od/ohs/biosfty/bmbl4/ bmbl4s6.htm
Barriers Primary barriers: physical barriers or
personal protective equipment between lab worker and pathogen Gloves, masks, special breathing apparatuses
Secondary barriers: structural aspects of the laboratory that make working environment safer against infection Sinks for handwashing, special containment
areas, special air ventilation patterns
Universal Precautions Universal precautions developed to protect health
professionals Most often apply in a clinical setting May also be important for field epidemiology practices
during an outbreak investigation (e.g., collecting lab specimens)
Include hand hygiene, gloves, gown, masks, eye protection, face shields, safe injection practices
Require that all equipment or contaminated items are handled to prevent transmission of infectious agents
Special circumstances may require additional precautions
Protective clothing, special site decontamination
Biosafety Level 1 (BSL-1)
Agents not known to cause disease in healthy adults Some organisms may cause disease
in immunocompromised individuals
Agents include Bacillus subtilis, Naegleria gruberi, infectious canine hepatitis virus, non-pathogenic E. coli species
(transmission electron micrograph of E. coli)
Biosafety Level 1 (BSL-1) Standard practices required:
frequent handwashing door that can be kept closed when working; limits on access to the lab space when
working; no smoking, eating, drinking, storage of food
in laboratory; care to minimize splashes and actions that
may create aerosols (tiny droplets); decontamination of work surfaces after every
use after any spills;
(continued on next slide)
Biosafety Level 1 (BSL-1) Standard practices (continued):
decontamination of laboratory wastes; use of mechanical pipettes only (no mouth
pipetting); "sharps" precautions, including special
containers for disposing of needles and other sharp objects;
maintenance of insect/rodent control program; use of personal protective equipment (lab
coats, latex gloves, eye protection or face shields)
Open bench top sink for hand washing
Biosafety Level 2 (BSL-2)
Agents associated with human disease Generally required for any human-
derived blood, bodily fluids, tissues in which infectious agent may be unknown
Agents include measles virus, Salmonella species, pathogenic Toxoplasma, Clostridium botulinum, hepatitis B virus
(transmission electron micrograph of hepatitis B virus)
Biosafety Level 2 (BSL-2) Primary hazards:
accidental needle sticks exposure to eyes and nose (mucous membranes) ingestion of infectious materials
Agents do not cause lethal infections, are not transmissible via airborne route
(do not cause infection if tiny droplets become airborne and are inhaled, which might occur if the material were spattered)
Agents are pathogens for which immunization or antibiotic treatment is available
Extreme care should be taken with contaminated needles and sharp lab instruments
Biosafety Level 2 (BSL-2) Standard practices include BSL-1 plus:
policies to restrict access to lab; biohazard warning signs posted outside lab; surveillance of laboratory personnel with
appropriate immunizations offered; biosafety manual with definitions of needed
waste decontamination or medical surveillance policies;
supervisory staff who have experience working with infectious agents and specific training for laboratory personnel in handling these agents
Biosafety Level 2 (BSL-2) Primary barriers: biosafety cabinets or
other approved containment devices Personal protective equipment: lab
coats, gloves, face protection as needed Protective clothing removed when
personnel leave laboratory area Cabinets thoroughly decontaminated
daily and monitored for radiation for personal protection
Secondary barriers: BSL-1 barriers plus autoclave for glassware
Biosafety Level 2 (BSL-2) Example of
biosafety sign posted outside lab working with infectious agents
Lab’s biosafety level
Infectious agents under study
Contact information for responsible person and 2 emergency contacts
Biosafety Level 3 (BSL-3) Agents with potential for respiratory
transmission, may cause serious and potentially lethal infection May be studied at BSL-2 for diagnosis
Agents include Mycobacterium tuberculosis, St. Louis encephalitis virus, Francisella tularensis, Coxiella burnetii
(F. tularensis under direct fluorescent antibody stain)
Biosafety Level 3 (BSL-3) Primary hazards: needle sticks, ingestion,
exposure to infectious aerosols For example:
Public health surveillance for West Nile virus includes testing birds
In August 2002, state laboratory worker cut finger while dissecting bird; 4 days later, had symptoms of fever, myalgia, recurring sweats, hot flashes
Worker and bird both diagnosed with West Nile 2 other lab-acquired cases in 2002
Biosafety Level 3 (BSL-3)
Tularemia common source of laboratory-acquired infection infections occur while handling infected
animals or experimenting with cultures Laboratory-acquired infections known
to occur but not reportable before 9/11/2001
Tularemia now classified as potential biological weapon
Biosafety Level 3 (BSL-3) Standard practices include BSL-2 plus:
strictly controlled access to the lab; specific training for lab personnel in
handling potentially lethal agents; decontaminating all waste; changing contaminated protective lab
clothing, decontaminating lab clothing before laundering;
institutional policies regarding specimen collection and storage from workers to establish exposure
Biosafety Level 3 (BSL-3) Primary barriers:
Similar to BSL-2 personal protective equipment
Respiratory equipment if risk of infection through inhalation
Secondary barriers: All BSL-2 barriers Corridors separated from direct access to lab Access through self-closing double doors Air handling systems to ensure negative air
flow (air flows into the lab) Air pumped into lab not re-circulated in
building
Biosafety Level 4 (BSL-4) Dangerous and exotic agents with high risk
of life-threatening disease, aerosol-transmitted
Related agents with unknown risk of transmission
Agents (all viruses) include Marburg virus, Ebola virus, viruses that cause Congo-Crimean hemorrhagic fever, Lassa fever
(transmission electron micrograph of Ebola virus)
Biosafety Level 4 (BSL-4) Primary hazards:
respiratory exposure to infectious aerosols mucous membrane exposure to infectious
droplets accidental sticks with needles or other sharp
objects contaminated with infectious material For example
In late 1960s, 25 laboratory-acquired Marburg infections, including 5 deaths
Workers studying infected monkeys from Uganda
First documented naturally-occurring human case occurred in 1975
Biosafety Level 4 (BSL-4) Personnel must receive specialized
training in handling extremely dangerous infectious agents, containment equipment and functions
Access to lab is restricted: immunocompromised persons are never allowed to enter the lab
Standard practices include BSL-3 plus: strictly controlled access to the laboratory; changing clothing before entering and exiting
lab (showering upon exiting recommended); decontaminating all material exiting facility
Biosafety Level 4 (BSL-4) Primary barriers:
Biosafety cabinets used at other biosafety levels
Full-body, air-supplied, positive pressure personnel suit
Secondary barriers: All physical barriers at BSL-3 isolated zone or a separate building; dedicated supply and exhaust, vacuum,
decontamination systems; a recommended absence of windows
(or sealed and resistant to breakage)
Laboratory Locations BSL-1: high schools, community colleges, municipal
drinking water treatment facilities BSL-2: local health departments, universities, state
laboratories, private laboratories (hospitals, health care systems), industrial laboratories (clinical diagnostic companies)
BSL-3: state health departments, universities, private companies, industry, federal government (NIH, CDC)
BSL-4: only 15 facilities in the US 9 federal (CDC, NIH), 4 university (Georgia State
University, University of Texas Medical Branch), 1 state, 1 private
Renovations underway at several labs, new facilities proposed at additional sites
Summary Laboratorians have long recognized hazards of
processing infectious agents Biosafety guidelines developed to protect
workers in microbiological and medical labs through a combination of safeguards including engineering controls, management policies and work practices.
Issue described differences between biosafety levels
Help you understand process labs may have to undertake to identify microorganism, why every lab cannot test for every organism
References1. US Department of Health and Human Services, Centers for
Disease Control and Prevention and National Institutes of Health. Biosafety in Microbiological and Biomedical Laboratories. 5th ed. Washington, DC: US Government Printing Office; 2007. http://www.cdc.gov/od/ohs/ biosfty/bmbl5/bmbl5toc.htm. Accessed February 6, 2008.
2. Clemson University Environmental Health and Safety. Biological Safety [online training]. http://ehs.clemson.edu/training/biosafety/index.html. Accessed February 6, 2008.
3. Centers for Disease Control and Prevention. Laboratory-Acquired West Nile Virus Infections — United States, 2002. MMWR Morb Mort Wkly Rep. 2002; 51:1133-1135. http://www.cdc.gov/mmwr/preview/ mmwrhtml/mm5150a2.htm. Accessed February 6, 2008.
4. United States Government Accountability Office. High-Containment Biosafety Laboratories: Preliminary Observations on the Oversight of the Proliferation of BSL-3 and BSL-4 Laboratories in the United States. Publication GAO-08-108T. http://www.gao.gov/docsearch/ abstract.php?rptno=GAO-08-108T. Published October 4, 2007.