Substances with a CAS-number that contain other substances sometimes cause confusion in a material declaration. The CAS-number system does not exclude the possibility that a substance with a CAS-number consists of a number of other substances with CAS-numbers. Examples are:

• Steel with CAS number 12597-69-2
• Brass with CAS number 12597-71-6

Each of these substances have a variable composition and may or may not include a reportable substance such as Lead (Pb). Declaring only “Steel” does not give information if lead is a constituent of the alloy or not. If a mixture (whether a solid (e.g. metal alloy), liquid, or gas) contains a declarable substance or declarable substance group, then this declarable substance or declarable substance must always be explicitly reported if present above the reporting threshold and if the reportable application is met.

Another issue that sometime arises in material declarations is when a supplier lists the elements that make up a compound rather than reporting the chemical compound itself. Many declarable substances are compounds which must be reported as listed in the IEC 62474 list of declarable substances. IEC 62474 does not allow the material declaration to report the separate elements that make up the compound. For example Disodium tetraborate, decahydrate (Borax) (CAS-number 1303-96-4 ) consists of Sodium, Boron and Oxygen, with CAS-numbers 7440-23-5, 7440-42-8.and 7782-44-7. Using these elemental CAS-numbers in the declaration will hide the existence of the declarable substance and violates the reporting requirement of IEC 62474.