Animal Biosafety

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Sugar Glider

The administration of infectious agents and recombinant and synthetic nucleic acid molecules to research animals poses unique hazards such as animal bites, scratches, shedding of agents, generation of aerosols, and contact with soiled bedding and equipment.  Animal Biosafety  Levels are required for use of experimentally-infected animals housed in our facilities, administration of rDNA to animals and maintenance of research animals that pose zoonotic disease risks.  

Administration of pathogenic organisms and viruses, recombinant and synthetic nucleic acid molecules and biological toxins must be approved by the IBC and the IACUC.  Animal biosafety levels are determined by the Institutional Biosafety Committee.

Animal Biosafety Levels

A set of four biosafety levels are provided for work with vertebrate animals exposed to agents which may infect humans. These Animal Biosafety Levels, ABSL-1 thru 4, provide for practices, equipment, and facilities that are comparable to the laboratory biosafety levels. However, there are unique hazards associated with infected animals that must be understood by those personnel with animal contact and addressed in the animal facility. Animal biosafety levels are designed to protect personnel from exposure to potentially infectious materials. Quarantine facilities and procedures must be utilized to prevent spread of infectious materials from animal to animal.

A good summary of the Animal Biosafety Levels can be found in the CDC/NIH Biosafety in Microbiological and Biomedical Laboratories, 6th edition.


Animal biosafety levels are the  minimum practices, equipment and facility requirements for research with exposed laboratory animals. 

ABSL Examples

ABSL-1:  adeno-associated virus (AAV)

ABSL-2: Pseudorabies virus, hepatitis A virus, S. aureus

ABSL-3: Mycobacterium tuberculosis

ABSL-4:  Ebola

Animal Biosafety Level 1 (ABSL-1)

ABSL-1 is suitable for animal work involving well-characterized agents that are not known to consistently cause diseases in immunocompetent adult humans and present minimal potential hazard to personnel and the environment.

Research at ABSL-1 can be conducted in LAR vivarium facilities and, if permitted by the IACUC and the IBC, in laboratories outside of the vivarium.


In LAR Animal Facility

Outside of LAR facilities, with permission from IACUC and IBC.


Standard PPE required by LAR to enter animal facility.

Wear safety glasses if splash hazard exists.

Laboratory coat, preferably disposable, and disposable exam gloves

Wear safety glasses if splash hazard exists.


Put on appropriaste PPE prior to entering animal facility or laboratory.

Wash hands after working with animals.

Eating, drinking, handling contact lenses, applying cosmetics and storing food for human consumption is not permitted.

Sharps must be disposed of directly, without recapping, into rigid impervious sharps containers.


As required by IACUC and LAR


Entrance to housing rooms must be labeled with a sign, provided by EHS, if animals have been exposed to microorganisms/ viruses.

Cages used to house animals that have been exposed to BSL 1 materials must be labeled by the researcher with the biosafety level, agent name and exposure date.

Labs where animals are exposed  to ABSL-1 agents should be labeled with a sign, provided by EHS.


EHS determines if soiled bedding should be disposed of via the regulated medical waste stream or via regular trash.

Carcasses are disposed of through the regulated medical waste stream.


Waste soiled bedding generated in the lab should be disposed of into the regulated medical waste receptacles.

Carcasses are returned to LAR, to be disposed of through the regulated medical waste stream.

Animal Biosafety Level 2 (ABSL-2)

ABSL-2 builds upon the practices, procedures, containment equipment and a facility requirements of ABSL11. ABSL-2 is suitable for work involving laboratory animals infected with agents associated with human disease and posing a moderate hazard to personnel and the environment. It also addresses hazards from ingestion and from percutaneous and mucous membrane exposure. Administration of agents requiring ABSL-2 containment must be conducted in LAR vivarium facilities.

In addition to the practice, facility, and equipment requirement recommended by CDC and NIH, ABSL-2 work at Princeton must be conducted in accordance with the following:


  • Change rodent cages inside of a BSC.
  • Administer infectious agents inside of a BSC, unless approved by the IBC.
  • Collect samples and conduct procedures within a BSC.
  • When transporting ABSL-2 animals out of the LAR vivarium facility, place cage inside of a biohazard bag or a drape.  Cages must be transported on carts.   Research staff are responsible for cleaning spills of soiled bedding that occur during transport.
  • Disinfect BSC using LAR-approved disinfectant before and after work.  Allow 10 minutes of contact time prior to wiping the surface with disposable towels.
  • Soiled bedding must be autoclaved prior to disposal.  Exceptions must be approved by the BSO(link sends e-mail).
  • All animal carcasses are returned to LAR for disposal.

Signs and Labels

  • Rooms signs, prepared by EHS, must be posted on the door of each ABSL-2 housing and procedure room. The signs include:
    • Universal biohazard symbol
    • Name of infectious agent
    • Personal protective equipment required to enter
    • Immunizations or medical surveillance required to enter
    • Required training
    • Principal Investigator and Laboratory Contact
    • Special husbandry precautions

A sample housing door sign where ABSL work takes place

Sample ABSL Door Sign

  • Cages used to house animals that have been exposed to BSL-2 materials must be labeled by the researcher with the biohazard symbol, ABSL-2, name of agent and date of exposure.  Label information must be understandable to all persons who may handle the cage and animal. Labels are provided by LAR.

ABSL Biohazard Cage Label

Biohazard cage label

Biohazard label shown in place on cage card

Biohazard placement on cage card


  • Small animals are housed in ventilated cage racks.  Larger animals may be housed in regular caging and additional PPE may be required.
  • Work in a BSC when:
    • Opening or changing rodent cages
    • Injecting small animals with infectious agents.

Note:  Stereotactic injections can be performed on the bench top but may require additional PPE.  IBC approval will specify additional PPE, if required.


Personal Protective Equipment

  • Shoe covers
  • Disposable gloves, preferably nitrile
  • Surgical mask
  • Hair bonnet
  • Disposable lab coat, fully-buttoned
  • If splash hazard exits, safety glasses may be required
  • Additional PPE may include sleeve covers and respiratory protection, if recommended by EHS.

Procedures for Administering Biohazards to Animals

Researchers who wish to administer biohazards, including microorganisms, viruses, recombinant and synthetic nucleic acid molecules, to animals, must obtain approval from the IACUC and the IBC prior to initiation of this work.

Working safely with biohazards in animals requires careful coordination with staff from Laboratory Animal Resources and EHS. After approval from both the IACUC and IBC has been received, the Principal Investigator and research staff must adhere to the following:

Before initiation of research:

  • Notify Laboratory Animal Resources (LAR) in advance of administration of the biohazard. For BSL 2 agents, 10 working days is required; for BSL 1 agents, provide at least 2 days' notice.
  • If requested by LAR, provide an overview of the research, with safety precautions required, to LAR staff.
  • Notify EHS prior to administration of any BSL 2 hazard to arrange for an evaluation of containment practices.

During research:

  • Conduct research in accordance with containment recommendations provided by the IBC.
  • Upon administration of a biohazard to animal, use the biohazard cage labels, provided by LAR, to, identify cages of animals that have been exposed. List the agent on the label and indicate ABSL-1 or 2.
  • Verify that a biohazard sign has been posted on the animal housing room door.
  • If administering biohazards to animals in a laboratory procedure space, request a biohazard sign for procedure room door from EHS.

Conclusion of research:

  • Notify LAR when research has been concluded, so that biohazard signs can be removed and precautions can be stopped.

Administration of Human-Derived Materials to Vertebrate Animals

All research protocols involving the deliberate introduction of materials of human origin into animals must be reviewed by the BSO and the IBC. A biocontainment level will be assigned based upon the outcome of a risk assessment.

Preparation and administration of primary human cells or tissues into animals and necropsy of
unfixed animals will be conducted at ABSL-2. Research animals injected or engrafted with primary human cells or tissues must be housed at ABSL-2, unless the BSO and the IBC determine, through a risk assessment, that the containment can be lowered. Factors involved in the assessment include, but are not limited to:

  • Availability of screening results showing that the specific sample to be used in animals is free of known bloodborne pathogens.
  • Animal’s immune status
  • Presence of other infectious agents in the animal.

Biosafety containment levels for research animals exposed to human cell lines will be
recommended by the BSO and the IBC. Preparation and administration of cell lines and necropsy of unfixed animals must be conducted using ABSL-2 containment. ABSL-1 is typically recommended for housing of these animals, but may be increased depending upon:

  • Availability of screening showing that the cell line to be used in animals is free of known BBP. Note: The LAR Attending Veterinarian and the BSO will provide recommendations for the frequency of human cell line testing on a case by case basis
  • Animal’s immune status
  • Presence of other infectious agents in the animal
  • Nature of the cell line
  • Nature of the transgene(s)

Animal Tissue-only Protocols

Research with animal tissues that may pose zoonotic disease risks must be approved by the IBC.  This includes tissues obtained from food processing facilities, slaughterhouses or are commercially available.   Research with tissue, secretions and excretions collected from non-human primates, sheep and any wild or field animal  always requires IBC approval.   Contact EHS ([email protected]) for questions about working with animal tissues.

Animal Worker Occupational Health Program

When research involves exposure to and handling of animals, there are considerations that must be given to the potential allergens, zoonoses, and physical hazards, e.g. bites and scratches, that may be encountered by researchers and staff. Consensus guidelines recommend and the U.S. Public Health Service policy requires that proper training and medical surveillance be provided for those working with research animals. The Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC) through which the University has received accreditation mandates an effective program for health and safety of animal workers.

The program is available to all faculty, staff and students who conduct research with vertebrate animals and those who enter animal housing areas to provide services.

The goals of the Animal Worker Occupational Health Program are to:

  • Provide a medical surveillance/evaluation that addresses species-specific risks.
  • Reduce potential for injuries and illnesses associated with animal research and entry into animal facilities by providing information on zoonoses, allergies and safe work practices.
  • Prevent transmission of infectious diseases that could negatively affect health of the research animals.
  • Provide medical treatment for all injuries and illnesses associated with animal research and entry into animal facilities.

Brown and White Guinea Pig

Animal Worker Medical Surveillance Program

Prior to beginning work with animals, all staff, faculty and students who have direct contact with animals are enrolled in the Animal Worker Occupational Health Program.

Enrollment in the program is initiated by the animal worker completing the web-based training, Health and Safety for Animal Workers or participating in an instructor-led training session provided by EHS.    After completion of the training, eligible staff, faculty and students are designated as “animal users” in the SHIELD system by the Laboratory Manager, supervisor or EHS. SHIELD  (Safety Health Inspection and Equipment Logistics Database) is the campus-wide health and safety management software and tracks the medical clearance status of all animal workers. 

The Animal Worker Medical Surveillance Program provides:

  • Occupationally-indicated immunizations and preventive health screening
  • Clinical evaluation and treatment for individuals with animal-related injuries or illnesses
  • Information on zoonotic diseases and how to prevent their transmission
  • Required screening/immunizations to prevent diseases which are naturally transmitted between vertebrate animals and humans

Allergies to Lab Animals

Animal-related asthma and allergies are exaggerated reactions of the body’s immune system to animal proteins known as allergens. Although some people who work with laboratory animals may never develop allergies or asthma, they do have a much higher risk of developing symptoms than those who do not work with animals.

Risk Factors

Some individuals may have pre-existing conditions that put them at higher risk of developing allergies or asthma when working with animals. If you have already experienced allergic responses to animals outside of work, you are probably at a higher risk of developing more serious disease with continued exposure to animal allergens.  Some studies suggest that if you have a history of allergic reactions, such as dermatitis and hay fever, to a variety of substances, you may be more likely to develop allergies to laboratory animals.

Signs and Symptoms

Most researchers who develop animal allergies present with a combination of symptoms, including:

  • Nasal congestion
  • Sneezing
  • Watery, itchy eyes

Although not as common as respiratory symptoms, some researchers may develop rashes or hives at the site of direct skin contact with allergens. Other skin symptoms include the development of hives under protective clothing, an allergic response to inhaling airborne allergens.

Ignoring these minor symptoms and continued exposure to allergens may result in the development of asthma  a serious disease that affects your personal health and possibly future career options. Asthma affects two percent of all people using animals during their first year of exposure and an additional two percent per year thereafter.

Allergen Sources and Routes of Exposure

Researchers who work with animals can develop allergies to any species. However, most reports of lab-related animal allergies are associated with rats and mice, due to their frequent use in animal research.

Animal allergens are low-molecular weight proteins excreted in urine and saliva. Most lab animal allergies in people who handle rodents are caused by exposure to proteins excreted in the urine.  The proteins stick to animal skin, hair and soiled bedding.

Animal allergens are carried on very small airborne particles. The airborne allergens can easily be inhaled. The most significant route of exposure to allergens for those who work with animals is inhalation. Other methods of exposure include direct skin and eye contact with allergens. 

In studies that evaluate airborne concentrations of allergens, animal caretakers who perform activities such as cage cleaning are at highest risk of exposure to allergens, followed by research staff who perform animal procedures. Support staff, such as those who work in an adjacent office are at lower risk, although studies have documented the presence of airborne animal allergens outside of animal facilities.

Controlling Your Exposure to Animal Allergens

The goal of the exposure control program is to reduce your animal allergen exposure to the lowest level possible. Minimizing your exposure can result in a reduction of allergic symptoms and prevent the development of laboratory animal allergies.

Our animal facilities are designed and maintained to reduce airborne allergens:

  • Ventilation systems provide 10-15 air exchanges per hour in animal housing and procedure rooms.
  • Bedding used in rodent cages sheds a minimum amount of dust.
  • Ventilated cage racks reduce airborne allergen emissions.
  • Frequent wet cleaning is conducted by husbandry staff.
  • Rodent cage bedding is changed within biosafety cabinets or animal transfer stations, which control operator exposure to airborne allergens.

Research and animal husbandry staff can:

  • Use biological safety cabinets when performing procedures on animals.
  • Reduce skin, hair and eye contact by using gloves, bonnets, protective masks and disposable gowns. 
  • Always wash your hands upon leaving the facility.
  • When spending long periods of time in the facility, change into scrubs and change out when leaving.
  • Participate in the medical surveillance program offered by Occupational Health.

Animal Allergies and Medical Surveillance

Every person who performs animal research or provides maintenance and support services on a regular basis in an animal facility must participate in the Animal Worker Medical Surveillance program. You will be asked to complete a brief health history when you first begin work and then again at regular intervals. If the information you submit indicates you are at risk or have already developed laboratory animal allergens, Occupational Health will conduct a detailed health assessment. If appropriate, you will be referred to a physician who specializes in diagnosing and treating allergies. Occupational Health, your allergist and specialists from Environmental Health and Safety will work together to develop a plan to reduce your exposure.

If lab animal allergy symptoms develop while working or conducting research at Princeton University, don’t delay contacting Occupational Health and informing your supervisor. Occupational Health and EHS will offer recommendations to reduce your exposure to allergens to the lowest level possible. These recommendations may include:

  • Use of gloves,  tight-fitting mask, head covering and long-sleeved disposable gown when working with or around animals.
  • Use of respiratory protection, which may include disposable air filtering half-face masks or powered air purifying respirators. At Princeton University, Environmental Health and Safety oversees the use of respirators, even if worn voluntarily.  You must be fitted, trained and medically evaluated before you wear a respirator, including an N-95 mask, to reduce exposure to laboratory animal allergens.

If you are concerned that your job or research may be affected if you report allergies to Occupational Health, consider some important facts:

  • Studies have shown that continued exposure to allergens may have a profound effect on your overall health.
  • Persons who fail to report and seek treatment for occupational asthma may continue to suffer severe and debilitating asthma attacks years after exposure to allergens has stopped.

There may be controls that can be used to decrease your exposure.  Occupational Health clinicians, allergists and specialists from Environmental Health and Safety can help you develop a plan.

Zoonotic Diseases

Prevention of zoonoses, diseases that can be transmitted between humans and animals, falls under the Biosafety program.   While many of the animals in our research program are bred to be free of infectious agents that can cause illness in humans, there are several notable exceptions, which can cause serious disease or death in humans.

For more information, visit the Zoonotic Disease Information Page.

Field Research Involving Vertebrate Animals

An elephant in the foreground on a plain in Africa

Field Research

Students, staff and faculty who conduct field research with vertebrate animals must enroll in the Animal Worker Medical Surveillance Program. Depending upon location of the research, you may also be required to consult with the Travel Health group, University Health Services. EHS is consulted for assistance with risk assessments. 

Requirements for consultation prior to travel for students, staff and faculty can be found at University Health Services’ Travel Health site.

The Travel Health clinicians address the risk considerations associated with the location of the research. EHS can assist with a risk assessment of the research, including biological, chemical and physical hazards.  These risks can include zoonotic diseases that could be transmitted from the animals studied in the field. Additionally, EHS can assist with a review of import permits and shipping restrictions for samples collected in the field as well as materials you plan to ship to the field research site.