ing with hazardous chemicals. This is particularly important if personal clothing leaves skin exposed. Apparel giving additional protection (e.g., nonpermeable laboratory aprons) is required for work with certain hazardous substances. Because many synthetic fabrics are flammable and can adhere to the skin, they can increase the severity of a burn. Therefore, cotton is the preferred fabric.

5.C.3 Housekeeping

There is a definite correlation between orderliness and level of safety in the laboratory. In addition, a disorderly laboratory can hinder or endanger emergency response personnel. The following housekeeping rules should be adhered to:

  • Never obstruct access to exits and emergency equipment such as fire extinguishers and safety showers.

  • Clean work areas (including floors) regularly. Properly label (see Chapter 3, section 3.B.4) and store (see Chapter 4, section 4.E) all chemicals. Accumulated dust, chromatography adsorbents, and other chemicals pose respiratory hazards.

  • Secure all compressed gas cylinders to walls or benches.

  • Do not store chemical containers on the floor.

  • Do not use floors, stairways, and hallways as storage areas.

5.C.4 Transport of Chemicals

Chemicals being transported outside the laboratory or between stockrooms and laboratories should be in break-resistant secondary containers. Secondary containers commercially available are made of rubber, metal, or plastic, with carrying handle(s), and are large enough to hold the contents of the chemical containers in the event of breakage. When transporting cylinders of compressed gases, the cylinder should always be strapped in a cylinder cart and the valve protected with a cover cap. When cylinders must be transported between floors, passengers should not be in the elevator.

5.C.5 Storage of Chemicals

The accumulation of excess chemicals can be avoided by purchasing the minimum quantities necessary for a research project. All containers of chemicals should be labeled properly. Any special hazards should be indicated on the label. For certain classes of compounds (e.g., ethers as peroxide formers), the date the container was opened should be written on the label. Peroxide formers should have the test history and date of discard written on the label as well. Only small quantities (less than 1 liter (L)) of flammable liquids should be kept at workbenches. Larger quantities should be stored in approved storage cabinets. Quantities greater than 1 L should be stored in metal or break-resistant containers. Large containers (more than 1 L) should be stored below eye level on low shelves. Hazardous chemicals and waste should never be stored on the floor.

Refrigerators used for storage of flammable chemicals must be explosion-proof, laboratory-safe units. Materials placed in refrigerators should be clearly labeled with water-resistant labels. Storage trays or secondary containers should be used to minimize the distribution of material in the event a container should leak or break. It is good practice to retain the shipping can for such secondary containers.

All chemicals should be stored with attention to incompatibilities so that if containers break in an accident, reactive materials do not mix and react violently.

(See Chapter 4, section 4.E, and Chapter 7, section 7.C.1.2, for more information.)

5.C.6 Disposal of Chemicals

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. The overriding principle governing the handling of waste in prudent laboratory practice is that no activity should begin unless a plan for the disposal of nonhazardous and hazardous waste has been formulated. Application of this simple rule will ensure that the considerable regulatory requirements for waste handling are met and that unexpected difficulties, such as the generation of a form of waste (e.g., chemical-radioactive-biological) that the institution is not prepared to deal with, are avoided.

Each category of waste has certain appropriate disposal methods. In choosing among these methods, several general principles apply, but local considerations can strongly influence the application of these rules:

  • Hazardous or flammable waste solvents should be collected in an appropriate container pending transfer to the institution's central facility or satellite site for chemical waste handling or pickup by an outside disposal agency.

  • Waste solvents can usually be mixed for disposal, with due regard for the compatibility of the compo-



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