Pay attention to the potential safety implications of subtle changes to experimental procedures. Slight changes to commonly performed operations often present unrecognized hazards. Changing solvents, suppliers, reagent concentration, reaction scale, and materials of construction may bring unintended consequences.

Determine the physical and health hazards associated with chemicals before working with them. This determination may involve consulting literature references, laboratory chemical safety summaries (LCSSs), material safety data sheets (MSDSs), or other reference materials (see also Chapter 4, section 4.B) and may require discussions with the laboratory supervisor, safety personnel, and industrial hygienists. Check every step of the waste minimization and removal processes against federal, state, and local regulations. Before producing mixed chemical-radioactive-biological waste (see Chapter 8, section 8.C.1.3) consult your institution’s or firm’s environmental health and safety (EHS) personnel.

Many of the general practices applicable to working with hazardous chemicals are given elsewhere in this volume (see Chapter 2). (See Chapter 5, section 5.F for detailed instructions on the transport of chemicals and section 5.E on storage; Chapter 7 for information on use and maintenance of equipment and glassware; and Chapter 8 for information on disposal of chemicals.)

6.C GENERAL PROCEDURES FOR WORKING WITH HAZARDOUS CHEMICALS

6.C.1 Personal Behavior

Demonstrating prudent behavior within the laboratory is a critical part of a culture of safety. This includes following basic safety rules and policies (see Chapter 2, section 2.C.1), being cognizant of the hazards within the laboratory (see Chapter 4), and exhibiting professionalism with co-workers. Maintaining an awareness of the work being performed in nearby hoods and on neighboring benches and any risks posed by that work is also important.

6.C.2 Minimizing Exposure to Hazardous Chemicals

Take precautions to avoid exposure by the principal routes, that is, contact with skin and eyes, inhalation, and ingestion (see Chapter 4, section 4.C, for a detailed discussion).

The preferred methods for reducing chemical exposure are, in order of preference,

1.   substitution of less hazardous materials or processes (see Chapter 5, section 5.B, Green Chemistry for Every Laboratory),

2.   engineering controls (Chapter 9),

3.   administrative controls (Chapter 2), and

4.   personal protective equipment (PPE)

See also the Occupational Safety and Health Administration’s (OSHA) Safety and Health Management eTool, Hazard Prevention and Control module available at www.osha.gov. Before beginning work, review all proposed laboratory procedures thoroughly to determine potential health and safety hazards. Refer to the MSDS for guidance on exposure limits, health hazards and routes of entry into the body, and chemical storage, handling, and disposal. Avoid underestimating risk when handling hazardous materials.

6.C.2.1 Engineering Controls

Engineering controls are measures that eliminate, isolate, or reduce exposure to chemical or physical hazards through the use of various devices. Examples include laboratory chemical hoods and other ventilation systems, shields, barricades, and interlocks. Engineering controls must always be considered as the first and primary line of defense to protect personnel and property. When possible, PPE is not to be used as a first line of protection. For instance, a personal respirator should not be used to prevent inhalation of vapors when a laboratory chemical hood (formerly called fume hoods) is available. (See Box 6.1 and Chapter 9 for more information about laboratory design and ventilation.)

6.C.2.2 Avoiding Eye Injury

Eye protection is required for all personnel and visitors in all locations where laboratory chemicals are stored or used, whether or not one is actually performing a chemical operation. Visitor eye protection should be made available at the entrances to all laboratories.

Researchers should assess the risks associated with an experiment and use the appropriate level of eye protection:

   Safety glasses with side shields provide the minimum protection acceptable for regular use. They must meet the American National Standards Institute (ANSI) Z87.1-2003 Standard for Occupational and Educational Eye and Face Protection, which specifies minimum lens thickness and impact resistance requirements.

   Chemical splash goggles are more appropriate



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