Laboratory Biosafety Levels

Goals Define barriers and procedures used by

laboratories to protect workers and others from infection

Describe the four biosafety levels and the protective measures used by each type of laboratory when handling infectious materials

Provide examples of the types of biological agents handled in each type of laboratory

Describe typical places where each type of laboratory can be found in the US

Why is Biosafety Important?

Laboratorians recognize hazards of processing infectious agents

Guidelines developed to protect workers in microbiological and medical labs through engineering controls, management policies, work practices

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.