• Containers are emptied faster, resulting in less chance for decomposition of reactive compounds.
• Use of the so-called “economy size” often dictates a need for other equipment, such as transfer containers, funnels, pumps, and labels. Added labor to subdivide the larger quantities into smaller containers, as well as additional personal protective equipment for the hazards involved, also may be needed. In most cases, it is safer, and may be less costly, to allow commercial providers to break bulk rather than “doing it yourself.”
• If unused hazardous material must be disposed of, the disposal cost per container is less for smaller containers.
An institution should also minimize the amount of chemical accepted as a gift or as part of a research contract. More than one laboratory has been burdened with the cost of disposing of a donated chemical that was not needed.
Donated material can easily become a liability. A chemical engineering researcher accepted a 55-gallon drum of an experimental diisocyanate as part of a research contract. The ensuing research project used less than 1 gallon of the material, and the grantor would not take the material back for disposal. No commercial incinerator would handle the material in its bulk form. The remaining material had to be transferred to 1-liter containers and sent as lab packs for disposal, at significant cost.
In section 5.D.2, the exchange or transfer of chemicals to other trained laboratory personnel is discussed. Smaller containers increase the chance that chemicals to be transferred are in sealed containers, which increases the receiver’s confidence that the chemicals are pure.
5.B.6 Minimize the Potential for Accidents
Green chemistry also means designing to reduce accidents, injuries, and exposures to laboratory, storeroom, and receiving personnel. Chapters 4 and 6 explain planning and risk assessment for laboratory personnel. Be sure that hazardous properties are understood before a material is purchased, synthesized, or otherwise acquired. Search references and the literature to be cognizant of the properties of explosivity, water and air reactivity, instability, age-related degradation, and pressurization when contained. Searches of historical laboratory accident data reveal risks associated with experimental setups, procedures, equipment, facilities, inadequate training, and noncompliance with safety rules. Trained laboratory personnel with this knowledge should communicate it to co-workers and material handling personnel. New laboratory personnel deserve a special orientation.
5.B.7 Green Chemistry Principles Avoid Multihazardous Waste Generation
Because the management of multihazardous waste is often difficult, prudent green chemistry principles minimize its generation. Chapter 8, sections 8.C.2 and 8.C.3, provides information on eliminating or minimizing the components of waste that are biological or radioactive hazards, respectively. For chemical– biological waste, the primary strategy for minimizing the multihazardous waste is to maintain segregation of chemical and biological waste streams as much as possible. For reduction of radioactive hazards, the strategies discussed include substituting nonradioactive materials for radioactive materials, substituting radioisotopes having shorter decay times (e.g., when radioactive iodine is specified, using iodine-131, with a half-life of 8 days, instead of iodine-125, with a half-life of 60 days), and carrying out procedures with smaller amounts of materials.
5.B.8 Mercury Replacements in the Laboratory
Chronic exposure to mercury (Chemical Abstracts Service [CAS] No. 7439-97-6) through any route can produce central nervous system damage (Mallinkrodt Baker, Inc., 2008). Common exposure routes include inhalation, ingestion, and skin or eye contact. Thermometers and manometers are the most common laboratory uses of elementary mercury, and in many cases, there are suitable nonmercury alternatives available. Broken thermometers and manometers create a health hazard in the laboratory and, where possible, should be replaced with mercury-free substitutes.
The consequences of broken mercury-filled equipment (thermometers, manometers, diffusion pumps, bubblers, etc.) can include personnel exposure, laboratory and environmental contamination, mercury spill cleanup, and disposal of mercury and mercury-contaminated debris. Mercury spills are challenging to clean up completely and require training and special spill control materials (see Chapter 6, section 6.C.10.8, for more information about mercury spill cleanup). Elemental mercury is very heavy and can be expensive to dispose as waste (Foster, 2005a). Replacing mercury-filled equipment in the laboratory ensures compliance with 2 of the 12 principles of green chemistry: No. 1, “Prevent Waste: Design chemical syntheses to prevent waste, leaving no waste to treat or clean up”; and No. 12, “Minimize the potential for accidents: Design chemicals and their forms (solid, liquid, or gas) to minimize the potential for chemical accidents including explosions, fires, and releases to the environment” (Anastas and Warner, 1998).