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Prudent Practices in the Laboratory: Handling and Disposal of Chemicals
be used to maintain an effective chemical inventory system. The integrity of the inventory system can be enhanced by the ease of making backup copies of the database. Searches for desired chemicals can be carried out in a number of ways, depending on the capability of the software. The ability to sort the database, for example, by hazard classification, acquisition date, or other parameters, and to prepare lists of the results of such a sort, can contribute to efficiency in a variety of chemical management tasks.
Section 4.C.1 above notes the prudence of establishing a central network of MSDSs. Including MSDSs and Laboratory Chemical Safety Summaries (LCSSs) (see Chapter 3 and Appendix B) in the inventory's database is highly desirable. The quality of MSDSs varies significantly from one manufacturer to another. LCSSs, which are targeted to the needs of the typical laboratory worker, are a useful supplement to the information provided by MSDSs.
Having a fully capable chemical tracking system depends on careful selection of more sophisticated database software. Such a package should permit access from multiple terminals or networked computers and, most importantly, have a foolproof, efficient method for rapidly recording the physical transfer of a chemical from one location to another. Barcode labeling of chemical containers as they are received provides a means of rapid, error-free entry of information for a chemical tracking system. If reagent chemical suppliers were to adopt a system in which chemical containers were labeled with bar codes providing essential information on their products, the maintenance of chemical tracking systems would be greatly facilitated. Proprietary software packages for tracking of chemicals are available. The investment in hardware, software, and personnel to set up and maintain a chemical inventory tracking system is considerable, but it can pay significant dividends in terms of economical and prudent management of chemicals.
As with any database, the utility of an inventory or chemical tracking system depends on the integrity of the information it contains. If an inventory system is used as a means of locating chemicals for use or sharing in the laboratory, even a moderate degree of inaccuracy will erode confidence in the system and discourage use. The need for high fidelity of data is greater for a tracking system, because laboratory workers will rely on it to save time locating chemicals using the system rather than physically searching. For these reasons, appropriate measures should be employed periodically to purge any inventory or tracking system of inaccurate data. A physical inventory of chemicals stored, verification of the data on each item, and reconciliation of differences can be performed annually. This procedure can coincide with an effort to identify unneeded, outdated, or deteriorated chemicals and to arrange for their disposal. The following guidelines for culling inventory may be helpful:
Consider disposing of materials anticipated not to be needed within a reasonable period, say, 2 years. Stable, relatively nonhazardous substances may have indefinite shelf lives; a decision to retain them in storage should take into account their economic value, scarcity, availability, and storage costs.
Make sure that deteriorating containers, or containers in which evidence of a chemical change in the contents is apparent (e.g., appearance of peroxide crystals in a bottle of an ether), are inspected and handled by someone experienced in the possible hazards inherent in such situations.
Dispose of or recycle chemicals before the expiration date on the container.
Replace deteriorating labels before information is obscured or lost.
Because many odoriferous substances will make their presence known despite all efforts to contain them, aggressively purge such items from storage and inventory.
Aggressively cull the inventory of chemicals that require storage at reduced temperature in environmental rooms or refrigerators. Because these chemicals may include air- and moisture-sensitive materials, they are especially prone to problems that can be exacerbated by the effects of condensation.
Dispose of, or remove to storage, all hazardous chemicals at the completion of the laboratory supervisor's tenure or transfer to another laboratory. The institution's cleanup policy for departing laboratory researchers and students should be enforced strictly to avoid accumulation of expensive orphaned unknowns.
Develop and enforce procedures relating to transfer or disposal of chemicals and other materials when decommissioning laboratories because of renovation or relocation.
4.D.2Exchange or Transfer of Chemicals
The exchange or transfer of chemicals between laboratories at an institution depends on the kind of inventory system and central stockroom facilities in place. Some institutions encourage laboratory workers to return materials to the central stockroom for redistribution to other workers. The containers may be sealed or open; a portion of the material may have been used. Materials from containers that have been opened are often of suffi-