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Prudent Practices in the Laboratory: Handling and Disposal of Chemicals
ufacturers) should be consulted, with careful consideration given to the permeability of any material, particularly when working with organic solvents, which may be able to permeate or dissolve the glove materials. The thin latex "surgical" vinyl and nitryl gloves that are popular in many laboratories because of their composition and thin construction may not be appropriate for use with highly toxic chemicals or solvents. For example, because latex is readily permeated by carbon disulfide, a hand covered by a latex glove immersed in carbon disulfide would receive constant wetting by this toxic chemical, which would by then be absorbed through the skin. Gloves should be replaced immediately if they are contaminated or torn. The use of double gloves may be appropriate in situations involving chemicals of high or multiple hazards. Leather gloves are appropriate for handling broken glassware and inserting tubing into stoppers, where protection from chemicals is not needed. Insulated gloves should be used when working with very hot or very cold materials. With cryogenic fluids the gloves must be impervious to fluid, but loose enough to be tossed off easily. Absorbent gloves could freeze on the hand and intensify any exposure to liquefied gases. Turning up the cuffs on gloves can prevent liquids from running down the arms when hands are raised.
Gloves should be decontaminated or washed appropriately before they are taken off and should be left in the work area and not be allowed to touch any uncontaminated objects in the laboratory or any other area. Gloves should be replaced periodically, depending on the frequency of use. Regular inspection of their serviceability is important. If they cannot be cleaned, contaminated gloves should be disposed of according to institutional procedures.
Barrier creams and lotions can provide some skin protection but should never be a substitute for gloves, protective clothing, or other protective equipment. These creams should be used only to supplement the protection offered by personal equipment.
6.F.2Safety and Emergency Equipment
Safety equipment, including spill control kits, safety shields, fire safety equipment, respirators, safety showers and eyewash fountains, and emergency equipment should be available in well-marked, highly visible locations in all chemical laboratories. Fire alarm pull stations and telephones with emergency telephone numbers clearly indicated must be readily accessible. In addition to the standard items, there may also be a need for other safety devices. It is the responsibility of the laboratory supervisor to ensure proper training and provide supplementary equipment as needed.
6.F.2.1 Spill Control Kits and Cleanup
In most cases, researchers are responsible for cleaning up their own spills. If a spill exceeds their ability or challenges their safety, they should leave the spill site and call the emergency telephone number for help. Emergency response spill cleanup personnel should be given all available information about the spill.
A spill control kit should be on hand. A typical cleanup kit may be a container on wheels that can be moved to the location of the spill and may include such items as instructions; absorbent pads; a spill absorbent mixture for liquid spills; a polyethylene scoop for dispensing spill absorbent; mixing it with the spill, and picking up the mixture; thick polyethylene bags for deposit of the mixture; and tags and ties for labeling the bags. Any kit should be used in conjunction with the personal protective equipment needed for the chemical that is to be cleaned up. Before beginning an operation that could produce a spill, the worker should locate the specialized spill control kits for that operation.
Safety shields should be used for protection against possible explosions or splash hazards. Laboratory equipment should be shielded on all sides so that there is no line-of-sight exposure of personnel. The front sashes of conventional laboratory exhaust hoods can provide shielding. However, a portable shield should also be used when manipulations are performed, particularly with hoods that have vertical-rising doors rather than horizontal-sliding sashes.
Portable shields can be used to protect against hazards of limited severity, such as small splashes, heat, and fires. A portable shield, however, provides no protection at the sides or back of the equipment, and many such shields not sufficiently weighted for forward protection may topple toward the worker when there is a blast. A fixed shield that completely surrounds the experimental apparatus can afford protection against minor blast damage.
Polymethyl methacrylate, polycarbonate, polyvinyl chloride, and laminated safety plate glass are all satisfactory transparent shielding materials. Where combustion is possible, the shielding material should be nonflammable or slow burning; if it can withstand the working blast pressure, laminated safety plate glass may be the best material for such circumstances. When cost, transparency, high tensile strength, resistance to bending loads, impact strength, shatter resistance, and burning rate are considered, polymethyl methacrylate offers an excellent overall combination of shielding characteristics.