Prudent execution of experiments requires not only sound judgment and an accurate assessment of the risks involved in the laboratory, but also the selection of appropriate work practices to reduce risk and protect the health and safety of trained laboratory personnel as well as the public and the environment. Chapter 4 provides specific guidelines for evaluating the hazards and assessing the risks associated with laboratory chemicals, equipment, and operations. Chapter 5 demonstrates how to control those risks when managing the inventory of chemicals in the laboratory. The use of the protocols outlined in Chapter 4 in carefully planned experiments is the subject of this chapter.

This chapter presents general guidelines for laboratory work with hazardous chemicals rather than specific standard operating procedures for individual substances. Hundreds of thousands of chemicals are encountered in the research conducted in laboratories, and the specific health hazards associated with most of these compounds are generally not known. Also, laboratory work frequently generates new substances that have unknown properties and unknown toxicity. Consequently, the only prudent course is for laboratory personnel to conduct their work under conditions that minimize the risks from both known and unknown hazardous substances. The general work practices outlined in this chapter are designed to achieve this purpose.

Specifically, section 6.C provides guidelines that are the standard operating procedures where hazardous chemicals are stored or are in use. In section 6.D, additional special procedures for work with highly toxic substances are presented. How to determine when these additional procedures are necessary is discussed in detail in Chapter 4, Section 4.C. section 6.E gives detailed special procedures for work with substances that pose risks due to biohazards and radioactivity, section 6.F addresses flammability, and section 6.G, reactivity and explosivity. Special considerations for work with compressed gases are the subject of Section 6.H. section 6.I covers microwave ovens, and section 6.J describes working with nanoparticles.

Chapter 7 provides precautionary methods for handling laboratory equipment commonly used in conjunction with hazardous chemicals. Chapters 4, 6, and 7 should all be consulted before working with hazardous chemicals.

Four fundamental principles underlie all the work practices discussed in this chapter. Consideration of each should be encouraged before beginning work as part of the culture of safety within the laboratory.

•   Plan ahead. Determine the potential hazards associated with an experiment before beginning.

•   Minimize exposure to chemicals. Do not allow laboratory chemicals to come in contact with skin. Use laboratory chemical hoods and other ventilation devices to prevent exposure to airborne substances whenever possible.

•   Do not underestimate hazards or risks. Assume that any mixture of chemicals will be more toxic than its most toxic component. Treat all new compounds and substances of unknown toxicity as toxic substances. Consider how the chemicals will be processed and whether changing states or forms (e.g., fine particles vs. bulk material) will change the nature of the hazard.

•   Be prepared for accidents. Before beginning an experiment, know what Specific action to take in the event of accidental release of any hazardous substance. Post telephone numbers to call in an emergency or accident in a prominent location. Know the location of all safety equipment and the nearest fire alarm and telephone, and know who to notify in the event of an emergency. Be prepared to provide basic emergency treatment. Keep your co-workers informed of your activities so they can respond appropriately.

Virtually every laboratory experiment generates some waste, which may include such items as used disposable labware, filter media and similar materials, aqueous solutions, and hazardous chemicals. (For more information about disposal of chemical waste, see Chapter 8.)


Before beginning any laboratory work, determine the hazards and risks associated with the experiment or activity and implement the necessary safety precautions. Ask yourself a hypothetical question before starting work: “What would happen if …?” Consider the possible contingencies and make preparations to take appropriate emergency actions. For example, what would be the consequences of a loss of electrical power or water pressure? Within each laboratory, all personnel should know the location of emergency equipment and how to use it, be familiar with emergency procedures, and know how to obtain help in an emergency. Laboratories should have a standing operational plan that describes how reactions, chemicals, and other laboratory processes will be handled in the case of a natural disaster or in the event that the individual responsible for laboratory activities is unavailable indefinitely (i.e., in the case of illness or death). Included in the plan should be emergency procedures and actions to be taken in the event that laboratory personnel experience a sudden medical emergency while performing an experiment.

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