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07 September 2001

Getting Information About Chemicals

by Sheldon Greaves

(Excerpted from The Amateur Scientist. The Complete 20th Century Collection on CD-ROM.)

Suppose you needed to know something about a chemical. What is it's boiling point? Melting point? Flash point? How toxic is it? What is the best way to store it? What do you do if it is toxic and someone is accidentally exposed to it?

Of the many publications and sources of information on the substances one might use in a laboratory setting, we will discuss two here. The first is a private publication, The Merck Index : An Encyclopedia of Chemicals, Drugs, and Biologicals. This is a large volume published annually. It is known chiefly as a drug and pharmaceuticals reference manual, but it also contains extensive information on chemicals, reagents, plants and naturally occurring substances.

The second source is the US Government. According to federal law, companies and who manufacture and sell chemicals must provide buyers with information about the chemical concerning its physical properties, storage, disposal, and safety issues. These data are usually published in Material Safety Data Sheets (MSDS). The government publishes guidelines for the content and organization of MSDS, although many companies (and some government agencies) depart slightly from these guidelines. Data sheets with much of the same kind of information are also published by international agencies as part of international standards of chemical nomenclature.

When reading a MSDS, there are usually some numbers used to refer to the chemicals under discussion. These numbers are listed under various abbreviations according to the body that assigned the number. Some of the more frequently encountered are:

CAS - Chemical Abstract Society. CAS maintains a list of Registry Numbers (often referred to as CAS RNs or CAS Numbers) that are unique identifiers for chemical substances based on references to them in academic and industry-related literature. CAS numbers provide an unambiguous way to identify a chemical substance or molecular structure when there are many possible systematic, generic, proprietary, or trivial names.

ICSC - International Chemical Safety Card. These information cards are developed by the International Programme on Chemical Safety (IPCS) . The project is being developed in the context of the cooperation between the IPCS and the Commission of the European Communities. The IPCS is a joint activity of three cooperating International Organizations: namely the United Nations Environment Programme (UNEP), the International Labour Office (ILO) and the World Health Organization (WHO). The main objective of the IPCS is to carry out and disseminate evaluations of the hazards posed by chemicals to human health and the environment. An ICSC summarizes essential health and safety information on chemicals for their use at the "shop floor" level by workers and employers in factories, agriculture, construction and other work places. ICSCs are not legally binding documents, but consist of a series of standard phrases, mainly summarizing health and safety information collected, verified and peer reviewed by internationally recognized experts, taking into account advice from manufacturers and Poison Control Centers.

RTECS - Registry of Toxic Effects of Chemical Substances. This chemical registry is compiled and maintained by the US National Institute for Occupational Safety and Health (NIOSH) provides toxicological information with citations on over 140,000 chemical substances. These detailed profiles include toxicological data and reviews; international workplace exposure limits; references to US standards and regulations; analytical methods; and exposure and hazard survey data.

The NIOSH maintains an online database of chemical safety cards at http://www.cdc.gov/niosh/ipcs/ipcs0000.html. It is also available on the Amateur Scientist CD-ROM by Tinker's Guild.