Where is the Chemical Abstract Service (CAS) number typically found for a chemical?

• A. On the SDS
• B. On the container label only
• C. In shipping papers
• D. In the manufacturer's brochure

Answer: (A)

The CAS number is a unique identifier assigned to each chemical substance by the American Chemical Society, used to unambiguously identify the exact chemical regardless of its name or synonyms. In hazmat work, the Safety Data Sheet is the standard document that communicates a chemical’s identity, hazards, and safe handling to workers. The SDS consistently includes the CAS number so responders and authorities can verify the precise substance being discussed. You might see the CAS number on other materials like container labels, shipping papers, or brochures, but those sources aren’t standardized for every chemical, making the SDS the most reliable place to find it.