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- This article is about the European Commission system for coding chemicals. For the Enzyme Commission codes, see Enzyme Commission number.
The European Commission number, or EC number, also known as EC No., EINECS No., and EC#, is a unique seven-digit identifier that is assigned to chemical substances for regulatory purposes within the European Union by the regulatory authorities. The list of substances having an EC number is called the EC Inventory.
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:
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.
The remainder is 9, which is the check digit.
Official EC inventory 
The EC Inventory includes the substances in the following inventories. The content of these inventories is fixed and official.
|Inventory||Scope||Format||No. of entries (if fixed No. of entries)|
|European Inventory of Existing Commercial Chemical Substances, (EINECS)||Substances, excluding polymers, that were recorded as being commercially available in the EU from 1 January 1971 to 18 September 1981. These were considered registered under Article 8(1) of the Dangerous Substances Directive (67/548/EEC). They are considered phase-in substances under the REACH Regulation||2xx-xxx-x
|European List of Notified Chemical Substances, (ELINCS)||Substances notified under the Dangerous Substances Directive Notification of New Substances (NONS) that became commercially available after 18 September 1981.||4xx-xxx-x||4,381|
|No Longer Polymers (NLP)||The definition of polymers was changed in April, 1992 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.||5xx-xxx-x||703|
List numbers 
ECHA also applies the EC number format to what it calls "List numbers". The number are assigned by when a substance is pre-registered or inquired about under the REACH Regulation. They are not official because they have not been published in the Official Journal of the European Union. The number of these two categories is open ended, as substances are continually being added.
|Automatically assigned, e.g. to pre-registrations of substances with a CAS No.||6xx-xxx-x|
|Assigned to substances after inquiries by the ECHA Substance ID Team||7xx-xxx-x|
|Automatically assigned, e.g. to pre-registrations without a CAS No. or other numerical identifier (including reaction masses of more than one substance)||9xx-xxx-x|
See also 
- Registration, Evaluation, Authorisation and Restriction of Chemicals
- European chemical Substances Information System
- CAS registry number
- European Chemicals Agency (November 2011). "Guidance for identification and naming of substances under REACH and CLP" (pdf). p. 118. Retrieved 2011-12-18.
- "Commission Directive 2001/59/EC of 6 August 2001 adapting to technical progress for the 28th time Council Directive 67/548/EEC on the approximation of the laws, regulations and administrative provisions relating to the classification, packaging and labelling of dangerous substances" (pdf). Official Journal of the European Communities (L 225): 4. August 21, 2001. Retrieved 2011-12-18.
- . doi:10.1080/02772249209357850. Missing or empty
- European Commission (30 April 1992). "Council Directive 92/32/EEC of 30 April 1992 amending for the seventh time Directive 67/548/EEC on the approximation of the laws, regulations and administrative provisions relating to the classification, packaging and labelling of dangerous substances" (pdf). Official Journal of the European Communities (L 154): 1–29. Retrieved 2009-01-25.
- "Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labeling and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006" (pdf). Official Journal of the European Communities (L 353): 329. December 31, 2008. Retrieved 2009-01-24.