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Laboratory Biohazard Exposure

203. Laboratory Biohazard Exposure

Work with hazardous biological agents in research laboratories has expanded as new infectious agents and diseases have emerged. Biological hazards include infectious or toxic microorganisms, potentially infectious human substances, and research animals, or their tissues, from which transmission of infectious agents or toxins is reasonably anticipated. It is crucial to provide safe methods, facilities and equipment for managing infectious materials in the microbiological and biomedical laboratories where they are being handled or maintained. The risk assessment of the work to be done with a specific biohazard helps to determine the appropriate combination of all above mentioned elements to reduce or eliminate exposure of the laboratory staff, the community, and the environment to potentially harmful biological agents. The safety principles described are based on sound safety practices, common sense, good housekeeping, thorough personal hygiene, and a plan for responding to accidents. It is likely that laboratories which are well organized and procedurally disciplined are not only effective scientifically, but safe as well. The most important element of safety when working with biohazardous materials is strict adherence to standard microbiological practices and techniques. Training is a key requisite to guarantee the fundamental objective of biological safety programs: a safer and healthier working environment for the campus community.


  • The Institutional Biosafety Committee (IBC) has been established at UT  Arlington to review all research involving recombinant DNA and other biohazardous materials used in research protocols to include
  • the Center of Disease Control (CDC)  Select Agent list (42 CFR Part 72). The IBC is a university-wide standing committee appointed by the President and shall be composed of no fewer than five members.
  • All principal investigators including faculty, staff, or students using rDNA or biohazardous materials in research, funded or non-funded, must submit a protocol with the IBC. All protocols should be filed with the Dean of the School of Science or through the current IBC designee. The Dean of the School of Science will then approve or refer a protocol for full IBC review and submit the protocols to the Office of Research for processing. The UT Arlington Office of Research will maintain all files, records and minutes of all IBC activities.
  • Principal Investigators contemplating research involving biological hazards are asked to register their research protocol with the Environmental Health & Safety Office.
  • To apply biological safety principles rationally while handling a potential pathogen, one must perform a risk assessment, which considers:
    • Agent’s biological and physical nature.
    • The sources likely to harbor the agent.
    • Host susceptibility.
    • The procedures that may disseminate the agent.
    • The best method to effectively inactivate the agent.
  • Pathogens are transmitted via several routes of infection, depending on the pathogen in question. The most common routes of infection are inhalation of infectious aerosols or dusts, exposure of mucous membranes to infectious droplets, ingestion from contaminated hands or utensils, or percutaneous selfinoculation (injection or incision). Appropriate precautions can be implemented to avoid such exposures.
  • Safety equipment includes biological safety cabinets (BSCs), enclosed containers, and other engineering controls designed to remove or minimize exposures to hazardous biological materials. The biological safety cabinet (BSC) is the principal device used to provide containment of infectious splashes or aerosols generated by many microbiological procedures.
  • An example of another primary barrier is the safety centrifuge cup, an enclosed container designed to prevent aerosols from being released during centrifugation. Centrifugation involving the use of gasket-sealable tubes, carriers and rotors, and containment controls such as BSCs must be used when handling infectious agents that can be transmitted through the aerosol route of exposure.
  • Accidental spilling of liquid infectious cultures is an obvious hazard due to the generation of aerosols (airborne droplets containing microorganisms). However, even routine manipulations of cultures may release microorganisms via aerosol formation:
    • Popping stoppers from culture vessels.
    • Opening closed vessels after vigorous shaking.
    • Spatter from flame-sterilizing utensils.
    • Expelling the final drop from a pipette.
  • Manipulate cultures of infectious material carefully to avoid aerosols or spills.
  • Seal microplate lids with tape or replace them with adhesive-backed Mylar film.
  • Load, remove and open tubes plates and rotors within a biological safety cabinet or fume hood.
  • When preparing aliquots of infectious material for long term storage, consider that viable lyophilized cultures may release high concentrations of dispersed particles if ampoules are not properly sealed. Breakage of ampoules in liquid nitrogen freezers may also present hazards because of survival and dispersal of pathogens in the liquid phase.
  • Equipment used for manipulations of infectious materials, such as cell sorters and automated harvesting equipment, must be evaluated to determine the need for secondary containment and to consider decontamination issues.
  • Use of human or animal cell cultures in laboratories requires special consideration. Cell or tissue cultures in general present few biohazards, as evidenced by their extensive use and lack of infection transmitted to laboratory personnel. Clearly, when a cell culture is inoculated with or known to contain an etiologic agent, it should be classified and handled at the same biosafety level as the agent.
  • Safety equipment also includes items for personal protection, such as gloves, coats, gowns, shoe covers, boots, respirators, face shields, safety glasses, or goggles. Personal protective equipment is often used in combination with biological safety cabinets and other devices that contain the agents, animals, or materials being handled. In some situations in which it is impractical to work in biological safety cabinets, personal protective equipment may form the primary barrier between personnel and the infectious materials.
  • Any specimen from human patients or animals may contain infectious agents. Specimens most likely to harbor such microorganisms include blood, sputum, cerebrospinal fluid, urine, semen, vaginal secretions, cerebrospinal fluid, synovial fluid, pleural fluid, pericardial fluid, peritoneal fluid, amniotic fluid, feces and tissues. Personnel in laboratories and clinical areas handling human blood or body fluids should practice universal precautions, an approach to infection control wherein all human blood and certain human body fluids are treated as if known to be infectious for human immunodeficiency virus (HIV), hepatitis B virus (HBV) and other bloodborne pathogens. Such personnel are required by law to be enrolled in the campus Bloodborne Pathogen Training Program (contact the Environmental Health &Safety Office, 817-272-2185, for information.)
  • Each laboratory should develop or adopt a biosafety or operations manual. The manual should identify the hazards that will or may be encountered, and specify practices and procedures designed to minimize or eliminate exposures to these hazards. Persons working with infectious agents or potentially infected materials must be aware of potential hazards, and they must be trained and proficient in the practices and techniques required for handling such material safely. The director or person in charge of the laboratory is responsible for providing or arranging the appropriate training of personnel. The laboratory director is responsible for selecting additional safety practices, which must be in keeping with the hazards associated with the agent or procedure. Laboratory personnel, safety practices, and techniques must be supplemented by appropriate facility design and engineering features, safety equipment, and management practices. The use of vaccines may provide an increased level of personal protection.
  • The design and construction of the facility contributes to the laboratory workers' protection, provides a barrier to protect persons outside the laboratory, and protects persons or animals in the community from infectious agents which may be accidentally released from the laboratory. Laboratory management is responsible for providing facilities commensurate with the laboratory's function and the recommended biosafety level for the agents being manipulated.