Chapter 2: Hazard assessment: determination and implementation of control measures in research laboratories
2.1 Hazard assessment in research laboratories
The need for appropriate control measures, when working in the laboratory, are determined by conducting a hazard analysis. A hazard analysis is the process of evaluating procedures in the laboratory, identifying the risks associated with the procedure and employing controls to minimize the risks. Results of the hazard analysis are then used to develop Standard Operating Procedures that define the controls, safe work practices and personal protective equipment (PPE) that are needed to work safely in the laboratory. It is essential to conduct a hazard analysis and create at least a basic SOP prior to working with any hazardous chemical for the first time.
The American Chemical Society (ACS) web page Hazard Assessment in Research Laboratories is an excellent source for information on different ways to identify and evaluate hazards in the laboratory:
Development of an effective SOP requires a comprehensive approach to hazard analysis. In addition to analyzing the hazards associated with each step of the experiment, an SOP must also consider other important aspects such as regulatory concerns, human factors (experience and training), the facility where the experiment will be performed, management of waste materials, emergency response, etc. Because of its comprehensive nature, development of an SOP requires more time and effort but results in a greater appreciation and understanding of the process of identifying potential hazards and mitigating associated risks. The following four methods of hazard analysis can be used as the first step in developing an SOP.
2.1.2 Job Hazard Analysis:
Job Hazard Analysis (JHA) focuses on a specific job or task performed in the laboratory. The job is broken down into individual steps. The possible hazards/risks associated with each step are considered and appropriate controls are identified to reduce or eliminate the risk. The steps of a completed JHA can be easily converted into SOPs for routine laboratory operations with known hazards.
2.1.3 What-if Analysis:
A what-if analysis is best suited to simple research applications. As the name implies, this analysis is structured around what if questions about the materials, the process or the equipment that will be used for the experiment. Controls to limit the identified risks are implemented based on the answers to these questions. This method of hazard analysis is easily understood and requires minimal training. However, it is essential that the person overseeing the analysis has sufficient knowledge and experience with the proposed research, to ensure that the right questions are asked.
A checklist provides convenient access to a list of criteria that can be easily checked and implemented by someone who is not familiar with the process of hazard analysis. However, a checklist is limited to the items on the list and may not be adequate for evaluating every hazard associated with your work. The gaps in a checklist may be filled by using other hazard analysis tools to identify other criteria to include on a customized checklist. Once customized for the task, process or working environment, a checklist is a very effective tool for ensuring that complex operations are safe.
2.1.5 Control Banding:
Control banding is best suited to laboratories performing routine procedures with known hazards. Using this approach, laboratory hazards are grouped into bands (categories) based on the nature of the hazard, the identified risks of working with or near the hazard, and the methods used to control the risks. For example chemicals in a laboratory can be grouped into four chemical safety levels (1-4) based on their chemical characteristics and the increasing risk associated with their use. Each successive safety level incorporates progressive implementation of controls and safe work practices to mitigate the increasing risks. After completing this process, a procedure or even an entire laboratory may be assigned to a specific safety level based on the chemicals being used. Everyone following this procedure or working in the lab understands the hazards and risks associated with the safety level and knows the controls and safe work practices that must be used.
2.2 Hazard analysis of chemical processes
Before beginning an experiment, consider all possible reactions, including side reactions, all reactants, intermediates, products, and wastes in terms of flammability, toxicity, and reactivity hazards. Consider the following:
- Does it decompose, and if so, how rapidly and to what products?
- What is its stability on exposure to heat, light, water, metals, or air?
- Is it impact sensitive?
- With what substances is this material incompatible?
- Is it toxic? look at the safety data sheet. If so, consider potential exposure routes such as inhalation, absorption, ingestion, and injection. Consider that exposure may occur by more than one of these routes.
- What is the recommended first aid treatment in case of an accidental exposure?
- What is the quantity and rate of the evolution of heat and gasses that may be released during the reaction?
- How will the waste products be handled and disposed?
2.2.1 Develop Contingency plans
Develop contingency plans that address the following:
- Electric power failure, including what will happen if power is restored when the device is unattended or being repaired;
- Cooling system failure;
- Exhaust system failure, including interruptions to laboratory exhaust, local exhaust, and filter/absorbent failures;
- Over pressurization;
- Interruptions of air, natural gas, or steam supply;
- Water leaks into the system;
- Air leaks into the system;
- A fire occurs due to the reaction;
- A reaction container breaks or contents spill;
2.2.2 During the process
Determine if any of the following are required:
- cooling, ventilation, pressure relief, and gas purging;
- isolation of the reaction vessel;
- warning signs near any dangerous processes and equipment;
- informing others working in the area about the possible hazards associated with chemicals and processes being used;
- evaluating safety of unattended operations -- processes that involve more serious or unusual hazards must be monitored continuously and should not be left unattended.
2.3 Additional resources for hazard evaluation
For information about a chemical, consult the manufacturer’s Safety Data Sheet (SDS) sheet. The following sources listed below may also provide additional information about the hazards associated with your proposed experiment.
PubChem database, hosted by the US National Library of Medicine, includes structural, physical and toxicological raw data, as well as chemical safety information form national and international agencies on over 90 million chemical compounds. Data provided by PubChem are intended to support, but not replace, laboratory risk assessments, Safety Data Sheets, and institutional guidance for safe laboratory practices and procedures.
toxnet.nlm.nih.gov/, a resource for searching databases on toxicology, hazardous chemicals, environmental hazards, and toxic releases.
OSHA Occupational Chemical Database 800 entries with information such as physical properties, exposure guidelines, and emergency response guidance.
OSHA Chemical Sampling Information file information on sampling and analysis of approximately 1500 substances.
NIOSH Pocket Guide to Chemical Hazards (information on several hundred chemicals commonly found in the workplace)
Environmental Protection Agency's (EPA's) Toxic Substance Control Act (TSCA) Chemical Substances Inventory information on more than 62,000 chemicals or chemical substances.