Risk Assessment and Biosafety Levels

The UNC Charlotte Biosafety Program acknowledges that, in the course of research, biohazards are used regularly in biomedical and applied science research settings on campus. All research investigators planning to use biohazardous agents should be knowledgeable about the characteristics of these agents and apply lab-based risk assessments of potential for adverse health or safety issues for research personnel regardless of agent biosafety or risk level classification. A risk management plan can be determined using the biosafety levels promulgated by the CDC. See below for detailed information on the elements to be considered when assessing and selecting the appropriate risk and biosafety levels to proposed research involving biohazards.

Pathogen The risks associated with the biohazardPractices Good microbiological work practices
Procedures Additional risks posed by the proposed manipulations Protective Equipment Protective clothing and engineering controls or containment equipment
Personnel Review of the people who will handle biohazards Place A review of the work location where biohazards will be handled

Risk Assessment

Risk assessment factors include the agent’s pathogenicity (ability to cause infection) and virulence (the severity of disease), the infectious dose, the availability of prophylaxis, communicability, and stability within the environment. The Risk Group Comparison Table below outlines the basic differences between each group.

Risk Group Comparisons*

CharacteristicsDoes not cause disease in healthy adults.Can cause infection of varying severity. Rarely lethal. Can be controlled using standard laboratory practices.Agents associated with moderate to severe disease outcome. Can be lethal.Capable of causing severe disease with lethal outcome.
Availability of TreatmentNot applicable.Treatment may be available or host immune system is capable of controlling the infection.Treatment may not be available.Treatment is generally not available. Experimental treatment regimens possible.
Routes of TransmissionNot applicable.Ingestion, through the skin, and via facial mucous membranes.Same as Risk Group 2 plus inhalation.Same as Risk Group 3.
Disease Severity to IndividualNone in healthy adults.Low to moderate.Moderate to high Higher mortality and morbidity.High Highest mortality rates in this category.
Community RiskLowLowLow to ModerateHigh Perception risk also very high.
Infections DoseNot applicableGenerally high (variable)Lower doses capable of infectionCan be as low as 1 organism
Example AgentsNon-conjugative strains of E. coli, Sacchromyces cerevisiae.Parasites (i.e. Plasmodium, Trypanosomes, Leishmania) GI pathogens (Salmonella, Shigella) Bloodborne Pathogens (HBV, HCV, Borrelia).Mycobacterium tuberculosis, West Nile Virus, Yellow Fever Virus, Rickettsia rickettsi.Ebola virus, Marburg virus, Sabia virus, Equine Morbillivirus.
Rule of Thumb**Don’t drink it! Never eat, drink or smoke in the laboratory.Don’t touch it! Wear gloves, decontaminate work surfaces, avoid touching your face, make sure wounds are covered, work in a BSC, wear eye protection, work behind a shield.Don’t breathe it! Because of inhalation risk, perform all work inside of a biosafety cabinet. Wear respiratory protection if needed.Don’t do it! (Don’t do it in your state unless you have a federally approved BSL4 laboratory!) Risk Group 4 agents require significant containment.

* Source: National Institutes of Health Centers for Disease Control and Prevention’s “Biosafety in Microbiological and Biomedical Laboratories” (6th Edition). **Source: Gwladys Caspar’s Quick Guide. The table above highlights some of the factors associated with a pathogen or biohazard that need to be identified when performing a risk assessment. Additional pertinent information regarding a pathogen is needed to help answer worst-case scenario questions such as:

  • How can workers be exposed to the biohazard?
  • Is there a high probability of infection if exposed?
  • Are there any other potentially harmful effects associated with the biohazard (reproductive pathogen, tumorigenic material, potential effects to the cell cycle)
  • Are others outside the laboratory (close contacts) at risk in the event of an Laboratory Acquired Infection (LAI)?
  • How long will the biohazard survive if it is released outside of primary containment or outside of the laboratory?
  • How difficult will it be to inactivate the biohazard upon completion of work or in the event of a spill or release?

Many government and regulatory agencies have developed formal Risk Group classifications for infectious agents based on various risk factors. A good starting point for assembling the information needed to conduct a risk assessment is the home page of the American Biological Safety Association (ABSA). Once on the ABSA home page, open the “Resources” link for access to the “Risk Group Database” and the following information:

  • Risk Group Classification for Infectious Agents
  • Material Safety Data Sheets (MSDS) Infectious Substances
  • Laboratory Centers for Disease Control – Canada
  • Bacteria – Viruses – Parasites – Fungi
  • Risk Group and Biosafety Level Definitions

Biosafety Levels

Biosafety levels are designated in ascending order, by degree of protection provided to personnel, the environment, and the community. Standard microbiological practices are common to all laboratories. Special microbiological practices enhance worker safety, environmental protection, and address the risk of handling agents requiring increasing levels of containment.

Biosafety Level 1:

Suitable for work involving well-characterized agents not known to consistently cause disease in immunocompetent adult humans, and present minimal potential hazard to laboratory personnel and the environment. Biosafety Level 2: Suitable for work involving agents that pose moderate hazards to personnel and the environment. It differs from BSL-1 in that: 1) laboratory personnel have specific training in handling pathogenic agents and are supervised by scientists competent in handling infectious agents and associated procedures; 2) access to the laboratory is restricted when work is being conducted; and 3) all procedures in which infectious aerosols or splashes may be created are conducted in Biosafety Cabinets (BSCs) or other physical containment equipment. Biosafety Level 3: Applicable to clinical, diagnostic, teaching, research, or production facilities where work is performed with indigenous or exotic agents that may cause serious or potentially lethal disease through the inhalation route of exposure. Source: National Institutes of Health Centers for Disease Control and Prevention’s “Biosafety in Microbiological and Biomedical Laboratories” (6th Edition). Appropriate biosafety practices by biosafety level‡ are detailed below in the chart.

Recommended Biosafety Levels for Infectious Agents

1Not known to consistently cause disease in healthy adults.Standard Microbiological Practices
  • No Primary barriers required
  • PPE: laboratory coats and gloves; eye, face protection, as needed
Open bench top sink required.
2Associated with human disease, hazard = percutaneous injury, ingestion, mucous membrane exposure. UNC Charlotte addition: any human pathogen is assumed to be at least a BSL-2 level classification.BSL-1 practice plus:
  • Limited accessBiohazard warning signs”Sharps” precautionsBiosafety manual defining any needed waste decontamination or medical surveillance policies
  • Primary barriers = Class I or II BSCs or other physical containment devices used for all manipulations of agents that cause splashes or aerosols of infectious materials;
  • PPEs: laboratory coats, gloves, face protection as needed
BSL-1 barriers plus:
Autoclave available
3Indigenous or exotic agents with potential for aerosol transmission; disease may have serious or lethal consequencesBSL-2 practice plus:
  • Controlled accessDecontamination of all wasteDecontamination of lab clothing before launderingBaseline serum
  • Primary barriers = Class I or II BCSs or other physical containment devices used for all open manipulations of agents;
  • PPEs: protective lab clothing, gloves, respiratory protection as needed
BSL-2 barriers plus:
  • Physical separation from access corridors.
  • Self-closing, double-door access
  • Exhausted air not recirculated
  • Negative airflow into laboratory

‡NOTE: Possession and use of biohazardous agents deemed to fall under Biosafety Level 4 (BSL-4) is prohibited on campus.

For investigators wishing to use transgenic animals monitored under the NIH Guidelines for Research Involving Recombinant or Synthetic DNA Molecules or to introduce biohazards into animals, the following animal biosafety practices are germane:

Recommended Biosafety Levels in which Vertebrate Animals are Used

1Not 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
  • Nonrecirculation of exhaust air
  • Directional air flow recommended.
2Associated with human disease, hazard = percutaneous injury, ingestion, mucous membrane exposure.ABSL-1 practices plus:
  • Limited accessBiohazard warning signs”Sharps” precautionsBiosafety manualDecontamination of all infectious wastes and animal cages prior to washing.
ABSL-1 equipment plus:
  • Primary barriersContainment equipment appropriate for animal speciesPPEs: laboratory coats, gloves, face and respiratory protection as needed
ABSL-1 facility plus:
  • Autoclave availableHand washing sink available in the animal room.
3Indigenous or exotic agents with potential for aerosol transmission; disease may have serious or lethal consequences.ABSL-2 practice plus:
  • Controlled accessDecontamination of cages before bedding removedDecontamination of lab clothing before launderingDisinfectant foot bath as needed
ABSL-2 equipment plus:
  • Containment equipment for housing animals and cage dumping activitiesClass I or II BCSs or other physical containment devices available for all manipulative procedures (inoculation, necropsy) that may create infectious aerosolsRespiratory protection
ABSL-2 facility plus:
  • Physical separation from access corridorsSelf-closing, double-door accessSealed penetrationsSealed windowsAutoclave available in facility

Source: Taken from the National Institutes of Health Centers for Disease Control and Prevention’s “Biosafety in Microbiological and Biomedical Laboratories” (6th Edition). Not sure which biosafety level to use? Contact Dr. Cathy Moore, Biosafety Officer, at 704‑687‑1825 or by email.