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Harmful agents
- A risk to humans or their environment
- Especially one presented by a toxic or infectious agent
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3 Major Types of Biohazards
- Biological: Animals are hazardous; they are natural reservoirs for disease. they can also be a source of allergens
- Chemical: all the cleaners we use for the animals; pest controls, contaminants in food and water. Some chemical hazards can turn into physical hazards
- Physical: Being bitten or scratched. Even the friendliest animals will bite you if hurt/injured
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Factors to consider:
- Infectious agent: Zoonotic or not (if it's zoonotic, we should be more concerned. Zoonotic dzs affect humans as well as animals)
- Animal: Lab animals and Wild animals
- Susceptible host: Healthy or ill; immunocompromised
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3 factors for workers to get sick:
- Mode of escape: from the animal; how does the infectious agent get out of the animal
- Mode of transmission: to the worker; how does it get to us from the animal
- Route of Exposure: Invade, enter, gain access to worker; once the disease/infection is in, how was it able to get thru
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Mode of Escape
- Natural: Any body excretions (urine, saliva, feces, blood)
- Skin lesions
- Artificial: Biopsy samples
- Blood collection
- Necropsy
- Surgical instruments
- Vectors
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Mode of Transmission
- Contaminated equipment: caging, racks, water bottles, etc. It doesn't matter what animal you're working with
- Needle and syringe is the biggest source of contaminant; most frequently documented incident
- Aerosols: The smaller the aerosol, the more they will linger. Larger particles settle on surfaces
- Sources may be: animals, bedding, in vitro (tissue culture flasks)
- Direct Contact: Workers themselves
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4 Primary Routes of Exposure (listed from least likely to most likely)
- Ingestion
- Contact with mucous membranes
- Inhalation
- Direct Parenteral Inoculation (needle stick); most common
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2 Major Concerns with Biohazards
- Potential for infection by aerosols: once it becomes aerosolized, it's more likely to get inside of us
- Severity of Disease: do we have to be worried about it or not
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Some other Concerns with biohazard control:
- Characteristics of animals
- Infectious agents involved: what do the animals harbor, and what do we harbor that could infect them
- Training/experience of personnel
- Activities/procedures being done
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Facility Managers
- Decide who gets into the lab and who doesn't.
- They also decide access levels for each person
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Barriers
- Anything between you and and the biohazard
- Could be what you're wearing, the airlocks, the cage, the room design, etc.
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Door warning Signs
- Warn you about what you're getting into
- Also gives you the name of who's responsible with internal phone number, home phone, and/or cell
- The kind of animal must be listed as well as what level of biohazard is being dealt with
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Biosafety Practices and Procedures
- Hygiene: wash hands frequently
- PPE: Personal Protective Equipment; anything you wear as a barrier. However, it's the last line of protection
- Needle/syringe use: most dangerous tool in the lab. Never recap and never use teeth. Every needle and syringe gets sterilized in labs before being disposed of
- Pipetting: Mechanical
- Housekeeping: Shouldn't use high pressure sprayers because they aerosolize everything. Update cleaners and chemicals. Autoclaving, washers, sweeping, mopping floors, etc.
- Pest Control: Always done by outside sources. Never use chemicals around the animals unless completely necessary
- Aerosols
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Containment (3 elements)
- Laboratory practice and technique
- Safety equipment
- Facility design
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Primary Containment
Protection of personnel and the immediate laboratory environment
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Secondary Containment
Protection of the environment outside of the laboratory
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Risk Assessment
Work to be done with a specific agent determines appropriate combination of these elements
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Laboratory Practice and Technique
- Most important element of containment
- Strict adherence to standard microbiological practices and techniques
- Employees must be aware of potential hazards
- Lab Manager must ensure proper training of employees
- Develop a Safety Manual
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Biological Safety Cabinet (BSC)
- Principle device used for containment
- Three types
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Safety centrifuge cup
Enclosed container designed to prevent aerosols from being released during centrifugation
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Facility Design/Construction (Secondary Barriers)
- Contributes to the laboratory workers' protection
- Protect persons outside the laboratory
- Protects persons or animals in the community
- Type of design based on risk assessment of hazards
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Facility Design/Constuctions may include:
- Separation of lab areas from general public
- Decontamination equipment
- Hand wash facilities
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Biosafety levels
- 4 exist
- Designated as BSL 1-4
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Biosafety levels consist of combinations of:
- Laboratory practices and techniques
- Safety equipment and laboratory facilities
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BSL-1
- Represents a basic level of containment
- Relies on standard microbiological practices
- No special primary or secondary barriers other than a sink
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Example organisms in BSL-1:
- Bacillus subtilis
- Naegleria gruberi
- infectious canine hepatitis virus
- exempt organisms under the NIH Recombinant DNA guidelines
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BSL-2
- Primary hazards to personnel are contaminated needles/sharps, mucous membrane exposure, and ingestion of infectious materials
- Must have both other primary and secondary barriers
- Used for any human-derived blood, body fluids, tissues, or primary human cell lines
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Example organisms in BSL-2:
- Hepatitis B virus
- HIV
- Salmonella
- Toxoplasma
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BSL-3
- More emphasis is placed on primary and secondary barriers
- All lab manipulations must be performed in a BSC
- Primary hazards to personnel working with these agents is autoinoculation, exposure to infectious aerosols, and ingestion
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Example organisms in BSL-3:
- Mycobacterium tuberculosis
- St. Louis encephalitis virus
- Coxiella burnetii
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BSL-4
- Primary hazards to personnel are respiratory exposure to infectious aerosols, mucous membrane or broken skin exposure to infectious droplets, and autoinoculation
- All agents pose a high risk of exposure and infection to laboratory personnel, the community, and the environment
- Practices, safety equipment, and facility design are for work with dangerous/exotic agents that pose a high risk of life-threatening disease
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