How to Find a CAS Number of a Product
A Chemical Abstracts Service (CAS) registry number is used by industry and governments worldwide as a universal identifier for chemicals. Unique CAS numbers are assigned to chemicals by the Chemical Abstracts Service, a division of the American Chemical Society, following an application process prompted by a chemical producer that is placing a new chemical on the market.
CAS numbers are easily recognized by their consistent formatting, a number segmented into three parts separated by dashes. The first set of numbers has a variable length, the second set of numbers is always 2 digits and the third set of numbers is always 1 digit. For example, the CAS Number for formaldehyde is 50-00-0, the CAS Number for phenol is 108-95-2 and the CAS Number for lead is 7439-92-1.
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Instructions
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Read the label or Material Safety Data Sheet (MSDS). If you have a specific product in mind and the product is a chemical or a mixture of chemicals, the CAS number is oftentimes readily available on the label and/or the MSDS. If you do not have access to the MSDS or label or if you are just looking for information on a particular chemical, make a note of the chemical's name and any synonyms that you may know.
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Use a trusted resource. There are many free search engines and websites that allow you to search for a CAS number. However, it is important to use a dependable, reputable resource because using a wrong CAS number can lead to serious problems in communicating chemical identity and hazard information. If you do not have a commercially available database on hand, open an Internet browser and visit ChemIDplus Lite, a database available from the U.S. National Library of Medicine (see the second link under References below).
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Type the chemical name into the search field of ChemIDplus Lite and click search. If the database has an exact match for that chemical name, you will be directed to a page that contains information on the chemical's identity, molecular structure, toxicity and links to other trusted websites with information on how the chemical is regulated. The CAS number appears on the landing page to this database record directly under the chemical name in the format of "RN: [XX]-XX-X" in bold numbers.
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Tips & Warnings
Be careful not to confuse CAS numbers with EC numbers, assigned to chemicals in Europe. EC Numbers take on the a structure of XXX-XXX-X. These numbers have three sections divided by dashes, but the first and second sets of numbers always have three digits.
