A key element of planning an experiment is assessing the hazards and potential risks associated with the chemicals and laboratory operations to be used. This chapter provides a practical guide for the trained laboratory personnel engaged in these activities. Section 4.B introduces the sources of information for data on toxic, flammable, reactive, and explosive chemical substances. Section 4.C discusses the toxic effects of laboratory chemicals by first presenting the basic principles that form the foundation for evaluating hazards for toxic substances. The remainder of this section describes how trained laboratory personnel can use this understanding and the sources of information to assess the risks associated with potential hazards of chemical substances and then to select the appropriate level of laboratory practice as discussed in Chapter 4. Sections 4.D and 4.E present guidelines for evaluating hazards associated with the use of flammable, reactive, and explosive substances and physical hazards, respectively. Finally, nanomaterials, biohazards, and radioactivity hazards are discussed briefly in sections 4.F and 4.G, respectively.

The primary responsibility for proper hazard evaluations and risk assessments lies with the person performing the experiment. That being said, the responsibility is shared by the laboratory supervisor. The actual evaluations and assessments may be performed by trained laboratory personnel, but these should be checked and authorized by the supervisor. The supervisor is also responsible for ensuring that everyone involved in an experiment and those nearby understand the evaluations and assessments. For example, depending on the level of training and experience, the immediate laboratory supervisor may be involved in the experimental work itself. In addition, some organizations have environmental health and safety (EHS) offices, with industrial hygiene specialists to advise trained laboratory personnel and their supervisors in risk assessment. When required by federal regulation, Chemical Hygiene Officers (CHOs) play similar roles in many organizations. As part of a culture of safety, all of these groups work cooperatively to create a safe environment and to ensure that hazards are appropriately identified and assessed prior to beginning work.


4.B.1 Chemical Hygiene Plan (CHP)

Beginning in 1991, every laboratory in which hazardous chemicals are used has been required by federal regulations (Occupational Safety and Health Administration [OSHA] Occupational Exposure to Hazardous Chemicals in Laboratories, 29 CFR § 1910.1450) to have a written CHP, which includes provisions capable of protecting personnel from the ‘’health hazards presented by hazardous chemicals used in that particular workplace.” All laboratory personnel should be familiar with and have ready access to their institution’s CHP. In some laboratories, CHPs include standard operating procedures for work with specific chemical substances, and the CHP may be sufficient as the primary source of information used for risk assessment and experiment planning. However, most CHPs provide only general procedures for handling chemicals, and prudent experiment planning requires that laboratory personnel consult additional sources for information on the properties of the substances that will be encountered in the proposed experiment. Many laboratories require documentation of specific hazards and controls for a proposed experiment.

4.B.2 Material Safety Data Sheets (MSDSs)

Federal regulations (OSHA Hazard Communication Standard 29 CFR § 1910.1200) require that manufacturers and distributors of hazardous chemicals provide users with material safety data sheets (MSDSs),1 which are designed to provide the information needed to protect users from any hazards that may be associated with the product. MSDSs have become the primary vehicle through which the potential hazards of materials obtained from commercial sources are communicated to trained laboratory personnel. Institutions are required by law (OSHA Hazard Communication Standard) to retain and make readily available the MSDSs provided by chemical suppliers. The MSDSs themselves may be electronic or on paper, as long as employees have unrestricted access to the documents. Be aware that some laboratories have been asked by local emergency personnel to print paper copies in the event of an emergency.

As the first step in risk assessment, trained laboratory personnel should examine any plan for a proposed experiment and identify the chemicals with toxicological properties they are not familiar with from previous experience. The MSDS for each unfamiliar chemical should be examined. Procedures for accessing MSDS files vary from institution to institution. In some cases, MSDS files are present in each laboratory, but often complete files of MSDSs are maintained only in a central location, such as the institution’s EHS office. Many laboratories are able to access MSDSs electroni-


1In the Globally Harmonized System for Hazard Communication, the term “material safety data sheet” has been shortened to “safety data sheet (SDS).” This book will continue to use the term MSDS as it is more recognizable at the time of writing than SDS.

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