Safety, Hazard Containment & Sterilising Equipment


How to use your risk assessment to select a biosafety cabinet Julianne L. Baron, PhD, CPH, RBP, President of Science and Safety Consulting


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Deciding which biological safety cabinet (BSC) works best for your lab based on your overall risk assessment


Conducting a risk assessment is recommended before performing experiments that may expose workers to hazardous materials [1-3]. However, you may be wondering what is a risk assessment, and how do I conduct one appropriate for my biological materials work? This article summarises information about conducting a risk assessment, mitigating risks, and selecting a biosafety cabinet based on your risk assessment.


What is a risk assessment?


A risk assessment is a process that evaluates the likelihood (chance/probability) and consequence (severity) of exposure to hazards [3]. Risk assessments are best completed by a team of individuals who understand all aspects of the hazards, staff capabilities, and facility and equipment features [1, 3].


Several health agencies provide information on how to conduct a risk assessment [1, 3]. The steps vary by organisation but generally seek to:


1. Assess the hazards associated with specifi c agents and with specifi c laboratory procedures


2. Determine and implement control measures


3. Provide ongoing review of the remaining risks and effectiveness of control measures [1-3]


Procedural risk factors


Features of the microbe(s) can impact the consequence and the likelihood of an exposure or release [1-3]. Once the biological materials have been characterised, then the materials handling can be assessed. Laboratory procedures that include generation of aerosols, use of sharps, animal handling, untrained or poorly trained staff, and facility or equipment defi ciencies may increase the likelihood of exposure. Laboratory work that includes genetic modifi cation of agents and/or use of large quantities or high concentrations of agents may increase the severity of exposure or release [1-3].


The overall risk is then calculated by plotting the likelihood and consequence of exposure [3]. Whether this level of risk is acceptable, or if there is need for risk reduction, will be subjective and requires consideration by individuals with knowledge of the hazards and the organisation’s leadership [1-3].


How Can I Reduce or Eliminate Identifi ed Risks?


After the risks are evaluated, you can determine ways to eliminate the hazard or minimise the likelihood and/or consequence of an exposure. Risk assessments and mitigation strategies must be specifi c to individual organisations and should not simply be transferred from one institution to another. The process of risk mitigation involves application of control measures represented in the ‘Hierarchy of Controls’ [4].


This hierarchy contains fi ve levels of controlling exposure to hazards listed from most to least effective [4]:


1. Elimination removes the hazard from the work entirely [4]. 2. Substitution replaces the hazard with a less hazardous alternative [4].


3. Engineering Controls physically modify equipment, facilities, and/or processes to separate personnel from the hazard [4].


4. Administrative Controls change the way the work is done [4].


5. Personal Protective Equipment (PPE) physically protects the individual by covering possible routes of exposure [4].


Commonly, a combination of controls from levels 3-5 is selected that collectively reduces the risk of exposure or release to an acceptable level [1]. For instance, when working with biological materials in a biosafety cabinet (engineering control), you may follow your research-specifi c SOPs (administrative control), and wear gloves and a lab coat (PPE).


These three control measures all depend on the effort of the individuals using them [4]. Engineering controls, like BSCs, require routine maintenance, cleaning, certifi cation,


There are three classes of BSCs that offer varying levels and types of protection [1, 5, 6]. Class I cabinets protect personnel and the environment but do not provide HEPA- fi ltered air to the work zone for the product’s protection [1, 5, 6]. If your risk assessment identifi es a need to protect the product from external contaminants, you may need to select a Class II or Class III biological safety cabinet.


Class II BSCs provide personnel, environment, and product protection by utilising an additional HEPA fi lter to provide clean air to the work zone to safeguard the product from cross- contamination. There are fi ve types of Class II BSCs which differ in the percentage of air that is recirculated versus exhausted, how they are connected to the building’s exhaust system, and whether they can accommodate work with hazardous or volatile chemicals [1, 5, 6]. Your risk assessment should identify which of these features are needed or whether a higher level of protection is needed.


Class III BSCs provide the highest level of personnel and environmental protection [1]. They also provide product protection and are typically used for highly hazardous work involving potentially infectious aerosols [1, 5]. There are additional logistical considerations for using a Class III BSC above and beyond those for Class I and Class II BSCs.


BSC class selection is reliant on the types of protection needed for the work. For example, Class II BSCs can be used at BSL-1 through BSL-4 [1, 6]. However, at BSL- 4, the use of Class II BSCs requires additional PPE and work in a specially designed laboratory [1].


and proper operational technique to ensure user protection. Administrative controls, such as personnel training and work procedures, require individuals to create and follow them appropriately. Furthermore, PPE must fi t the individual and be worn correctly to be considered protective. There is no single ‘catch-all’ for risk mitigation that can eliminate all risk, other than abstaining from hazardous work entirely. Finally, risk assessments are meant to be cyclical and evaluate the effectiveness of the employed control measures in reducing risk [1, 3].


How does my risk assessment fi t into biosafety cabinet selection?


When considering the use of engineering controls, specifi cally biosafety cabinets, it is important to understand the different classes and types of BSCs, how they differ, and what limitations they may have based on the proposed work to be performed.


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