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Prudent Practices in the Laboratory: Handling and Disposal of Chemicals
toxic laboratory chemicals, that is, chemicals having an LD50 of less than 50 mg/kg (oral; rat)).
These lists may be updated periodically by EPA.
7.B.2.3 Determining the Status of a Waste
The EPA regulations place on the waste generator the burden of determining whether the waste is regulated as hazardous and in what hazard classification it falls. Testing is not necessarily required, and in most cases the laboratory worker should be able to provide sufficient information about the waste to allow the hazard classification to be assigned. If the waste is not a common chemical with known characteristics, enough information about it must be supplied to satisfy the regulatory requirements and to ensure that it can be handled and disposed of safely. Often, information on only the components present in amounts greater than 1% is required, but confirmation is needed from the treatment/disposal facility. The information needed to characterize a waste also depends on the method of ultimate disposal. (See the discussion of disposal methods in sections 7.B.6 to 7.B.8 below.)
7.B.3Collection and Storage of Waste
7.B.3.1 At the Location of Generation
The first step in the disposal sequence usually involves the accumulation and temporary storage of waste in or near the laboratory (satellite accumulation). This step directly involves the laboratory workers who are familiar with the waste and its generation and is a most important part of ensuring that the disposal process proceeds safely and efficiently. It is often the time at which a decision can be made to recycle or reuse surplus materials rather than sending them for disposal. All of the costs and benefits of either decision should be evaluated here.
Again, safety considerations must be of primary concern. Waste should be stored in clearly labeled containers in a designated location that does not interfere with normal laboratory operations. Ventilated storage may be appropriate.
Federal regulations allow the indefinite accumulation of up to 55 gallons of hazardous waste or 1 quart of acutely hazardous waste at or near the point of generation. However, prudence dictates that the quantities accumulated should be consistent with good safety practices. Furthermore, satellite accumulation time must be consistent with the stability of the material. It is generally recommended that waste not be held for more than 1 year. Within 3 days of the time that the amount of waste exceeds the 55-gallon (or 1 quart) limit, it must be managed under the storage and accumulation time limits required at a central accumulation area. (See Chapter 9, section 9.D.4, for more information.)
Often, different kinds of waste can be accumulated within a common container. Such commingled waste must be chemically compatible to ensure that heat generation, gas evolution, or another reaction does not occur. (See the discussion of commingling in section 7.B.3.2 below.)
Packaging and labeling are a key part of this initial in-laboratory operation. Waste must be collected in dependable containers that are compatible with their contents. Glass containers have traditionally been the most resistant to chemical action, but they can break easily. Metal containers are sturdier than glass, but often are corroded by their contents. Various chemically resistant plastic containers are becoming preferable substitutes for containers of glass or metal. Safety cans, metal or plastic, should be considered for holding flammable solvents. It is advisable to use secondary containers, such as trays, in case of spills or leakage from the primary containers. Containers are required to remain closed except when their contents are being transferred. Containers of incompatible materials should be separated physically or otherwise stored in a protective manner.
Every container must be labeled with the material's identity and its hazard (e.g., flammable, corrosive). Although the identity need not be a complete listing of all chemical constituents, it should enable knowledgeable laboratory workers to evaluate the hazard. However, when compatible wastes are collected in a common container, it is advisable to keep a list of the components to aid in later disposal decisions. Labeling must be clear and permanent. Although federal regulations do not require posting the date when satellite accumulation begins, some states do require this. The institution may suggest that this information be recorded as part of its chemicals management plan.
7.B.3.2 At a Central Accumulation Area
The central accumulation area is an important component in the organization's chemicals management plan. In addition to being the primary location where waste management occurs, it may also be the location where excess chemicals are held for possible redistribution. Along with the laboratory, the central accumulation area is often where hazard reduction of waste takes place through allowable on-site treatment processes.