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Prudent Practices in the Laboratory: Handling and Disposal of Chemicals
tute (ANSI). The following is a guide to the information typically found in an MSDS:
Name of supplier (with address and phone number) and date MSDS was prepared or revised. Toxicity data and exposure limits sometimes undergo revision, and for this reason MSDSs should be reviewed periodically to check that they contain up-to-date information. Phone numbers are provided so that, if necessary, users can contact the supplier to obtain additional information on hazards and emergency procedures.
Name of the chemical. For products that are mixtures, this section may include the identity of most but not every ingredient. Common synonyms are usually listed.
Physical and chemical properties. Data such as melting point, boiling point, and molecular weight are included here.
Physical hazards. This section provides data related to flammability, reactivity, and explosibility hazards.
Toxicity data. OSHA and American Conference of Governmental Industrial Hygienists (ACGIH) exposure limits (as discussed below in section 3.C) are listed. Many MSDSs provide lengthy and comprehensive compilations of toxicity data and even references to applicable federal standards and regulations.
Health hazards. Acute and chronic health hazards are listed, together with the signs and symptoms of exposure. The primary routes of entry of the substance into the body must also be described. In addition, potential carcinogens are explicitly identified. In some MSDSs, this list of toxic effects is quite lengthy and may include every possible harmful effect the substance can have under the conditions of every conceivable use.
Storage and handling procedures. This section usually consists of a list of precautions to be taken in handling and storing the material. Particular attention is devoted to listing appropriate control measures, such as the use of engineering controls and personal protective equipment necessary to prevent harmful exposures. Because an MSDS is written to address the largest scale that the material could conceivably be used on, the procedures recommended may involve more stringent precautions than are necessary in the context of laboratory use.
Emergency and first aid procedures. This section usually includes recommendations for firefighting procedures, first aid treatment, and steps to be taken if the material is released or spilled. Again, the measures outlined here are chosen to encompass worst-case scenarios, including accidents on a larger scale than could conceivably occur in a laboratory.
Disposal considerations. Many MSDSs provide guidelines for the proper disposal of waste material.
Transportation information. It is important to remember that this chapter is concerned only with evaluating the hazards and assessing the risks associated with chemicals in the context of laboratory use. MSDSs, in contrast, must address the hazards associated with chemicals in all possible situations, including industrial manufacturing operations and large-scale transportation accidents. For this reason, some of the information in an MSDS may not be relevant to the handling and use of that chemical in a laboratory. For example, most MSDSs stipulate that self-contained breathing apparatus and heavy rubber gloves and boots be worn in cleaning up spills, even of relatively nontoxic materials such as acetone. Such precautions, however, might be unnecessary in the case of laboratory-scale spills of acetone and other substances of low toxicity.
Originally, the principal audience for MSDSs comprised health and safety professionals (who are responsible for formulating safe workplace practices), medical personnel (who direct medical surveillance programs and treat exposed workers), and emergency responders (e.g., fire department personnel). With the promulgation of federal laws such as the Hazard Communication Standard (29 CFR 1910.1200) and the OSHA Laboratory Standard (29 CFR 1910.1450), the audience for MSDSs has been expanded to include laboratory workers in industrial and academic laboratories. However, not all MSDSs are written to meet the requirements of this new audience effectively.
In summary, among the currently available resources, MSDSs remain the best single source of information for the purpose of evaluating the hazards and assessing the risks of chemical substances. However, laboratory workers should recognize the limitations of MSDSs as applied to laboratory-scale operations:
The quality of MSDSs produced by different chemical suppliers varies widely. The utility of some MSDSs is compromised by vague and unqualified generalizations and internal inconsistencies.
MSDSs must describe control measures and precautions for work on a variety of scales, ranging from microscale laboratory experiments to large manufacturing operations. Some procedures outlined in an MSDS may therefore be unnecessary or inappropriate for laboratory-scale work. An unfortunate consequence of this problem is that it tends to breed a lack of confidence in the relevance of the MSDS to laboratory-scale work.
Many MSDSs comprehensively list all conceivable health hazards associated with a substance without differentiating which are most significant and which are most likely to actually be encountered. This can make it difficult for laboratory workers to distinguish highly hazardous materials from moderately hazardous and relatively harmless ones.