The biological risk assessment process is used to identify the hazardous characteristics
of an infectious or potentially infectious agent or material, if known; the activities
that can result in a person’s exposure to an agent; the likelihood that such exposure
will cause a Laboratory Associated Infection (LAI); and the probable consequences
of such an infection. The information identified by risk assessment will provide a
guide for selection of the appropriate mitigations, including the application of biosafety
levels and good microbiological practices, safety equipment and facility safeguards
that can prevent LAIs. Risk assessments should be performed prior to beginning work
with a biohazardous agent or at any time when a change occurs to existing procedures,
protocols and standard operating procedures.
Identify hazardous characteristics of the agent and perform an assessment of the inherent
risk (i.e., what is the agent Risk Group?). Risk Group classifications indicate the specific hazards associated with a particular
bacteria, virus, or other biohazard. Risk Group classifications are based on an agent's
capability to infect and cause disease in a susceptible host, severity of disease,
and the availability of preventative measures and effective treatments. Other items
of concern include possible routes of transmission of infection, infectious dose,
host range, genetic characteristics of the agent. Consult the references listed below
for your agent(s).
Identify laboratory procedure hazards. Procedures that produce aerosols, working with sharps, working with animals (zoonotic
diseases), working with large/concentrated volumes of biohazardous agent(s), working
with cell cultures derived from human/primate cultures or materials (bloodborne diseases)
as well as many other procedures carried out in a typical laboratory can have varying
levels of risk associated with them.
Determine the appropriate Biosafety Level (BSL) and select additional precautions
indicated by the risk assessment. The selection of the appropriate BSL and any additional laboratory precautions require
a comprehensive understanding of the practices, safety equipment, and facility safeguards
described in the BMBL 6th ed (link below).
Review the selected safeguards with a biosafety professional, subject matter expert,
and the IBC or equivalent resource. This review is strongly recommended and may be required by regulatory or funding
agencies.
Evaluate the proficiencies of the staff regarding safe practices and the integrity
of safety equipment. Laboratory directors or principal investigators should ensure that laboratory personnel
have acquired the technical proficiency in the use of microbiological practices and
safety equipment required for safe handling of the agent(s). This includes the ability
to recognize hazards and how to handle emergency situations and obtain assistance
if necessary.
Regularly revisit and verify risk management strategies and determine if changes are
necessary. This includes a regular update of biosafety manuals and SOPs when changes in procedures
or equipment occur.
Infectious agents or pathogens are disease-causing microorganisms. There are hundreds
of microorganisms that cause disease in humans and animals. They can be classified
as bacteria, fungi, viruses, prions, or parasites. The principal hazardous characteristics
of an agent are its capability to infect and cause disease in a susceptible human,
animal or plant host, its virulence as measured by the severity of disease, and the
availability of preventive measures and effective treatments for the disease. Other
hazardous characteristics of an agent include probable routes of transmission of laboratory
infection, infective dose, stability in the environment, host range and endemic nature.
Each infectious agent or microorganism can be categorized by four levels of hazard
known as Risk Groups. It is important to keep in mind that in many instances a risk
group will correlate with a biosafety level (e.g., RG-2 agent will be handled at BSL-2)
but they are not equivalent (e.g., some RG-3 agents may be safely manipulated at a
BSL-2 under certain conditions).
NIH Guidelines Definition of Risk Groups
Risk Group 1 (RG1) - Agents that are not associated with disease in healthy adult
humans. This group includes a list of animal viral etiologic agents in common use.
The agents represent no or little risk to an individual and minimum risk to the community.
Risk Group 2 (RG2) - Agents that associated with human disease which is rarely serious
and for which preventative or therapeutic interventions are often available. These
agents represent moderate risk to an individual but a low risk to the community.
Risk Group 3 (RG3) - Agents that are associated with serious or lethal human disease
for which preventative or therapeutic interventions may be available. These agents
represent a high risk to the individual and a low to moderate risk to the community
depending on the pathogen.
Risk Group 4 (RG4) - Agents ("Exotic Agents") that are likely to cause serious or
lethal human disease for which preventative or therapeutic interventions are not usually
available. The agents represent a high risk to the individual and a high risk to the
community.
For biological agents to cause disease, they must first enter or invade the body
in sufficient numbers. Routes of entry include oral, respiratory, parenteral, mucus
membrane, and animal contacts (bites or scratches). Once inside the body, biohazardous
agents must colonize cells, tissues and/or organs and overcome the body's defense
mechanisms in order to cause disease.
Other factors contribute to an individual's susceptibility to the disease process.
These include age, immunological state, predisposing conditions, occupation physical
and geographic location.
Investigations of Laboratory Acquired Infections (LAIs) have identified five principal
routes of laboratory transmission. These are parenteral inoculations with syringe
needles or other contaminated sharps, spills and splashes onto skin and mucus membranes,
ingestion, animal bites and scratches, and inhalation exposures to infectious aerosols.
The first four routes of transmission re fairly easy to detect. However, up to 80%
of all reported LAIs are suspected to be caused by infectious aerosols thereby making
them the predominant route for transmission of biologically hazardous agents.
Route of exposure
Protective measures
Mucous Membranes – Exposure via the mucous membranes, eyes, nose, or mouth due to
splash/splatter.
Protect face by:
Wearing safety glasses and a surgical mask or a full-face shield.
Working in a Biological Safety Cabinet (BSC) or behind a protective shield.
Following good microbiological practices.
Inhalation – Breathing in respirable aerosols (particles <5 µm) due to centrifuge
leaks, spills, or aerosol-generating procedures such as pipetting and homogenizing.
Avoid exposure to aerosols by:
Working in a BSC.
Using sealed rotors or canisters when centrifuging.
Following good microbiological practices.
Using respiratory protective equipment.
Ingestion – Exposure from mouth pipetting or eating, drinking, or smoking in the laboratory.
Prevent exposure via ingestion by:
Never eating, drinking, or smoking in the laboratory.
Always using mechanical pipettors.
Following good microbiological practices.
Using gloves and frequent hand washing.
Percutaneous – Exposure through intact or non-intact skin via needlestick, puncture
with a contaminated sharp object, animal scratch or bite, or through wounds, abrasions,
or eczema.
Prevent percutaneous injuries by:
Substituting plastic for glass.
Using extreme caution and/or engineering controls with sharps. i.e., never recapping
needles.
Discarding sharps immediately into a rigid leakproof sharps container.
Wearing cut-resistant gloves and sleeves.
Properly restraining animals.
Covering non-intact skin with waterproof bandages and wearing double gloves.
Indirect Contact – Touching mucous membranes or non-intact skin with hands that have
been in contact with contaminated surfaces, such as benches, phones, and computers,
or hands that were not washed after working.
Prevent indirect exposure by:
Decontaminating work surfaces frequently (at least once a day).
Always washing hands when finished working, after removing gloves, and before leaving
the lab.
Not touching face (either with gloves or non-gloved hands - good personal hygiene).
