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Prudent Practices in the Laboratory: Handling and Disposal of Chemicals
Of the various resources that describe the properties of selected chemicals, two listed in Chapter 3 deserve particular comment: Material Safety Data Sheets and Laboratory Chemical Safety Summaries.
Federal law requires that Material Safety Data Sheets (MSDSs) be provided to users of chemicals by their manufacturers and distributors. MSDSs provide necessary information about precautions for protecting against known hazards associated with the subject product and often include useful information on chemical, physical, and toxicological properties, along with suggestions for storing, transporting, and disposing of chemicals. MSDSs are the best general source of information available, and they should be consulted as a first step in assessing the risk associated with doing an experiment. However, because there is currently no standard format for MSDSs, their quality varies widely, and the information that they contain may be inappropriate for laboratory use.
In consideration of the special problems of planning chemical experiments in the laboratory, the committee prepared Laboratory Chemical Safety Summaries (LCSSs) for 88 carefully chosen chemicals; these summaries are included as Appendix B of this book. Since many of these 88 chemicals are representative of a class of potentially hazardous compounds, the LCSSs can also be used as guides to handling many other compounds with related chemical structures. The LCSSs provide concise critical discussions, in a style readily understandable to laboratory workers, of the toxicity, flammability, reactivity, and explosibility of the subject chemicals. Directions for handling, storage, and disposal and special instructions for first aid and emergency response are given. The 88 LCSSs provide considerably greater coverage of specific and representative chemicals than was available in Prudent Practices 1981 and Prudent Practices 1983 and, unlike most MSDSs, are designed especially for laboratory workers.
Virtually every stage in the life cycle of a chemical has undergone dramatic change during the past 15 years as the new culture of laboratory safety has become established. Necessarily, the new ways that chemicals are acquired, tracked through an institution, stored, and delivered to the laboratory must be considered in contemporary experiment planning along with the detailed conduct of the experiment and the follow-up stages of handling all products and waste. Factors that once played at most a minor role in the handling of chemicals are now central. Almost all of these are related directly or indirectly to the legal, bureaucratic, and associated financial costs that have resulted from elevating the priority of safety in the workplace and protection of the public and the environment. The costs of documenting, handling, and disposing of all unwanted chemicals (i.e., waste) from completed experiments have increased enormously. Consequently, strategies that once were accepted as prudent, frugal, or, at worst, harmless are now no longer common practice. Fortunately, a number of technical advances, such as miniaturization and the large-scale management of information by computers, have allowed partial accommodation to the new forces affecting education and research in laboratories. Still, there is no doubt that the way science is done has changed enormously and that allowing adequate time and money for managing chemicals has become a major factor in planning experiments. Chapter 4 contains guidelines for the safe acquisition and storage of hazardous chemicals.
The prudent handling of chemicals now requires reducing the volume of every component to the minimum necessary to achieve the goals for which it was acquired. Any excess should be disposed of quickly and legally, unless there is a justifiable future use for it. In minimizing risks to laboratory, transport, and storeroom personnel, and to minimize the cost of waste disposal, source reduction is the first step. One should order and have on hand only what is necessary for currently planned experiments. No longer is it frugal to accept gifts of unneeded materials on the chance that they might be useful in the future or to buy the "large economy size" and store unused leftover chemicals for potential but unknown applications. The American Chemical Society booklet "Less Is Better" (1993) emphasizes the safety and financial reasons for buying chemicals in small packages: reduced risk of breakage, reduced risk of exposure following an accident, reduced storage cost, reduced waste from decomposition during prolonged storage in partially empty bottles, and reduced disposal cost for small containers of unused material. A well-planned experiment should reflect the "just in time'' acquisition strategies used in modern manufacturing. If possible, the responsibility for storing and inventorying chemicals should remain with the supplier.
For chemicals likely to be used in the near future, storage is reasonable and can be a frugal component of a well-managed plan for handling chemicals. In general, though, if a chemical has not been used during the two years since it was placed in laboratory storage, the chance is small that it will ever be used again. Three years is a reasonable deadline for use, recognizing the value of shelf space, the deterioration of many chemicals, and the enormous price of disposal if the label decomposes or falls off and the compound becomes an "unknown." Unused remainders can be handled