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CAS Registry Number (CASRN)

Last updated: July 23, 2017

What Does CAS Registry Number (CASRN) Mean?

CAS Registry Numbers (CASRN), or CAS Numbers, are unique numerical numbers assigned to every chemical substance described in available scientific literature dating back to 1957. Chemical substances are registered with CAS Numbers by the Chemical Abstracts Service, a division of the American Chemical Society. The purpose of CAS numbers is to avoid confusion between similarly named or abbreviated chemicals, or chemicals with multiple names or trade names. Their formal, systematized nature allows CAS numbers to act as an efficient, internationally recognized, and easily validated link to information about their associated chemical substances. With over 102 million chemical substances registered, CAS numbers act as a universal identification system that allows chemicals substances to be reliably identified without respect to linguistic, professional, or regional context.

Safeopedia Explains CAS Registry Number (CASRN)

CAS Numbers are divided into three parts by hyphens, and contain up to ten digits. The first part of the number ranges from two to seven digits, the second part contains two digits, and third part is a single check digit. Chemical substances are given CAS numbers in sequential order as they are added to the CAS Registry database. As such, CAS numbers do not organize substances according to any category and have no significance to the number they are associated with other than as a method of identification. Approximately 15,000 new substances are given CAS Numbers and added to the registry database each day.

The value of CAS numbers is recognized by occupational health and safety organizations worldwide. OSHA’s Hazard Communication Standard (HCS) provides regulations relating to the use of CAS numbers to identify hazardous substances. OSHA requires that CAS Numbers be present on the mandatory labels and Safety Data Sheets (SDS) that must be included with commercial chemical substances, especially hazardous substances. These standards are used as part of OSHA’s compliance with the various labelling and SDS standards that are mandated by the United Nations’ Globally Harmonized System of Classification and Labelling of Chemicals (GHS). CAS numbers are used by OSHA and under other GHS-compliant systems to allow efficient access to the health and safety information associated with a particular substance.


Chemical Abstracts Service Registry Number

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