# EC number (chemistry): Wikis

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# Encyclopedia

The European Commission number, or EC number, also known as EC-No and EC#, is the seven-digit code that is assigned to chemical substances that are commercially available within the European Union. This number is assigned by the Commission of the European Community; the EC number is the official number of a substance in the European Union.

The list of substances having an EC number is called the EC Inventory.[1] The EC Inventory includes the substances in the following inventories.

• European Inventory of Existing Commercial Chemical Substances, EINECS
These are substances, excluding polymers, that were commercially available in the EU from 1 January 1971 to 18 September 1981. These were considered registered registered under Article 8(1) of directive 67/548/EEC
The identifying number of these substances is called the EINECS number.
• European List of Notified Chemical Substances, ELINCS
These are substances that became commercially available after 18 September 1981.
The identifying number of these substances is called the ELINCS number.
• The "No-longer Polymers" list, NLP-list
The definition of polymers was changed in April, 1992[2] with the result that substances previously considered to be polymers were no longer excluded from regulation. Consequently, a list, called the NLP-list, was made of such substances that were commercially available between after 18 September 1981 and 31 October 1993.[3]
The identifying number of these substances is called the NLP number.

After the pre-registration phase of REACH, ECHA has additionally assigned list numbers in the 6xx-xxx-x series to substances pre-registered with a CAS number. The 9xx-xxx-x series has been allocated to pre-registered reaction masses of more than one substance or which were pre-registered with only a chemical name as an identifier. You can see these in the ECHA List of pre-registered substances.

For a substance in one of these lists, its identifying number, which will be either an EINECS number, an ELINCS number, or an NLP number, is also its EC number. The format of the identifying numbers in all three lists is the same; also, the numbers in these lists do not overlap.

The EC number is made up of seven digits according to the pattern xxx-xxx-x.[4]

• EINECS numbers start with number 200-001-8 (formaldehyde). There are currently 100,204 entries.[5]
• NLP numbers start with 500-001-0 ("2-methylpropene, trimers"). There are currently 703 entries.

The EC Number may be written in a general form as: NNN-NNN-R, where R is a check digit and N represents integers. The check digit is calculated using the ISBN method. According to this method, the check digit is the remainder of the following sum after division by 11:

$\frac{N_1 + 2\!\times\!N_2 + 3\!\times\!N_3 + 4\!\times\!N_4 + 5\!\times\!N_5 + 6\!\times\!N_6}{11} = Q + \frac{R}{11}$

If the remainder R is equal to 10, that combination of digits is not used for an EC number.

To illustrate, the EC number of dexamethasone is 200-003-9. N1 is 2, N2 through N5 are 0, and N6 is 3.

$\frac{2 + 2\!\times\!0 + 3\!\times\!0 + 4\!\times\!0 + 5\!\times\!0 + 6\!\times\!3}{11} = \frac{20}{11} = 1 + \frac{9}{11}$

The remainder is 9, which is the check digit.

The substance to which an EC number refers (and vice versa) can be looked up on the official "European Chemical Substances Information System" web site, ESIS.