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B. Designated Areas

A key requirement of the OSHA Laboratory Standard is that all work with particularly hazardous substances be confined to designated areas. A designated area is defined as a laboratory, an area of a laboratory or a device such as a laboratory hood that is posted with warning signs that ensure that all employees working in the area are informed of the hazardous substances in use there.


It is the responsibility of laboratory supervisors to define the designated areas in their laboratories. These areas shall be posted with conspicuous signs reading "DESIGNATED AREA FOR USE OF PARTICULARLY HAZARDOUS SUBSTANCESAUTHORIZED PERSONNEL ONLY. In some cases it may be appropriate to post additional signs describing unusual hazards present and/or identifying the specific hazardous substances in use.
Laboratory hoods serve as designated areas for most of the research groups at USC. Laboratory supervisors are required to notify the Chemical Hygiene Officer of the specific location of any designated areas established in their research groups that are not laboratory hoods.

C. General Procedures for Work with Substances Or Moderate to High Chronic Toxicity or High Acute Toxicity

The following general procedures should be followed in work with substances with high acute toxicity i.e. substances that can be fatal or cause serious damage to target organs as the result of a single exposure of short duration. These procedures should also be employed in laboratory operations using those carcinogens and reproductive toxins for which infrequent, small quantities do not constitute a significant hazard, but which can be dangerous to workers exposed to high concentrations or repeated small doses. A substance that is not known to cause cancer in humans, but which has shown statistically significant, but low, carcinogenic potency in animals, generally should also be handled according to the procedures outlined in this section. Work with more potent carcinogens and reproductive toxins requires the additional precautions described in Part VII.D below. Keep in mind that the general rules for work with toxic substances discussed in Part VI.C of this Chemical Hygiene Plan also apply to work with "Particularly Hazardous Substances".


(1) Information
Before beginning a laboratory operation, each researcher should consult the appropriate literature (see Part IV and references in Part XII) for information about the toxic properties of the substances that will be used. The precautions and procedures described below should be followed if any of the substances to be used in significant quantities is known to have high acute or moderate chronic toxicity. If any of the substances being used is known to be highly toxic, it is desirable that there be at least two people present in the area at all times. These procedures should also be followed if the toxicological properties of any of the substances being used or prepared are unknown. If any of the substances to be used or prepared are known to have high chronic toxicity (e.g., compounds of certain heavy metals and strong carcinogens), then the precautions and procedures described below should be supplemented with the additional precautions outlined in Part VII.D.
(2) Zero skin contact
Contact with the skin is a frequent mode of injury. Many toxic substances are absorbed through the skin with sufficient rapidity to produce systemic poisoning. Avoid all skin contact with particularly hazardous substances by using suitable protective apparel including the appropriate type of gloves (see Prudent Practices, pp. 158-160) or gauntlets (long gloves) and a suitable laboratory coat or apron which covers all exposed skin. See Part V.B for a further discussion of protective apparel. Always wash your hands and arms with soap and water immediately after working with these materials. In the event of accidental skin contact, the affected areas should be flushed with water and medical attention should be obtained as soon as possible.
(3) Use laboratory hoods
Inhalation of toxic vapors, mists, gases, or dusts can produce poisoning by absorption through the mucous membrane of the mouth, throat, and lungs, and can seriously damage these tissues by local action. Inhaled gases or vapors may pass rapidly into the capillaries of the lungs and be carried into the circulatory system. This absorption can be extremely rapid. Procedures involving volatile toxic substances and those operations involving solid or liquid toxic substances that may result in the generation of aerosols must be conducted in a hood or other suitable containment device. The hood should have been evaluated previously to establish that it is providing adequate ventilation and has an average face velocity of not less than 80 linear ft/min. See Part V.D for further discussion of the operation of laboratory hoods.

(4) Be prepared for accidents


The laboratory worker should always be prepared for possible accidents or spills involving toxic substances. To minimize hazards from accidental breakage of apparatus or spills of toxic substances in the hood, containers of such substances should generally be stored in pans or trays made of polyethylene or other chemically resistant material and (particularly in large scale work) apparatus should be mounted above trays of the same type of material. Alternatively, the working surface of the hood can be fitted with a removable liner of sorbent plastic-backed paper. Such procedures will contain spilled toxic substances in a pan, tray, or sorbent liner and greatly simplify subsequent cleanup and disposal.
If a major release of a particularly hazardous substance occurs outside the hood, then the room or appropriate area should be evacuated and necessary measures taken to prevent exposure of other workers. Call EHS (777-5269) for assistance and equipment for spill clean-up; personnel can be contacted for assistance after working hours by calling Campus Police (777-9111). Spills should only be cleaned up by personnel wearing suitable personal protective apparel. If a spill of a toxicologically significant quantity of toxic material occurs outside the hood, a supplied-air full-face respirator should be worn. Contaminated clothing and shoes should be thoroughly decontaminated or incinerated. See Part VI.C.12 for further discussion of the control of accidental releases of toxic substances.
(5) Don't contaminate the environment
Vapors that are discharged from experiments involving particularly hazardous substances should be trapped or condensed to avoid adding substantial quantities of toxic vapor to the hood exhaust air. The general waste disposal procedures outlined in Part VI.C.11 should be followed; however, certain additional precautions should be observed when waste materials are known to contain substances of moderate or high toxicity. Volatile toxic substances should never be disposed of by evaporation in the hood. If practical, waste materials and waste solvents containing toxic substances should be decontaminated chemically by some procedure that can reasonably be expected to convert essentially all of the toxic substances to nontoxic substances (for a discussion, see Prudent Practices for Disposal of Chemicals from Laboratories, pp. 56-100 and Destruction of Hazardous Chemicals in the Laboratory by G. Lunn and E. B. Sansone). If chemical decontamination is not feasible, the waste materials and solvents containing toxic substances should be stored in closed, impermeable containers so that personnel handling the containers will not be exposed to their contents. In general, liquid residues should be contained in glass or polyethylene bottles half-filled with vermiculite. All containers of toxic wastes should be suitably labeled to indicate the contents (chemicals and approximate amounts) and the type of toxicity hazard that contact may pose. For example, containers of wastes from experiments involving appreciable amounts of weak or moderate carcinogens should carry the warning: CANCER SUSPECT AGENT. All wastes and residues that have not been chemically decontaminated in the exhaust hood where the experiment was carried out should be disposed of in a safe manner that ensures that personnel are not exposed to the material.
(6) Record keeping
Every research group in the Department is required to maintain a list of all particularly hazardous substances in use in their laboratories. It is recommended that Group Safety Officers be assigned the responsibility for ensuring that this inventory list is kept up to date. In addition, records that include amounts of material used and names of workers involved should be kept as part of the laboratory notebook record of all experiments involving particularly hazardous substances.
(7) Restrict access to areas where particularly hazardous substances are in use
Those operations involving particularly hazardous substances in which there is the possibility of accidental release of harmful quantities of the toxic substance must be carried out in designated areas As discussed in Part VII.B, many laboratory hoods are designated areas for work with particularly hazardous substances. Designated areas should be posted with special warning signs indicating that particularly toxic substances may be in use.

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