June 11, 2015 by Becky Marks


The 2018 REACH registration deadline is fast approaching and with so many substances due to be registered substance identity is set to be a huge issue.

Before commencing with the other parts of a REACH registration, it is vital that companies have a clear answer to the following question:

  • What exactly is the substance that needs to be registered?

That may sound straightforward but, with an increasing focus on substance identity and substance sameness under REACH, it can be one of the most complex (and time consuming!) aspects of preparing a REACH registration, with historical substance naming often confusing the issue further. This is also an area that has been the focus of ECHA’s compliance checks.

The basis for substance identity decisions has to be solid analytical data. Although some analytical techniques may not be relevant for all substances the key is to demonstrate, through a combination of analytical methods, that the substance is what you say it is. Without sound analysis confirming what the substance is it is impossible to demonstrate substance sameness with other SIEF members or to show that the substance you are registering matches the one tested in the hazard assessment.

Based on the analytical data, substance sameness needs to be demonstrated between SIEF members. Substance Identity Profiles are often developed by the Lead Registrant, or by a consortium, to describe the substance which the registration covers. As Joint Registrants, companies are responsible for demonstrating that the substance they are registering is the same as the one being registered by the Lead Registrant. During this process, it can sometimes become apparent that a SIEF needs to be split and separate registrations submitted.

Another important aspect of substance identity is identifying the type of substance to be registered: mono-constituent, multi-constituent or UVCB (substance of unknown or variable composition, complex reaction products or biological materials). According to ECHA’s guidance on substance identity these can be defined as follows:

Mono-constituent: Defined based on composition, with one constituent present at ≥80% w/w. Naming should be based on the identifiers of the main constituent and any impurities >1% should be named, as well as any impurities contributing to classification or PBT assessment.

Multi-constituent: Defined based on composition, with more than one constituent ≥10% and <80%. Naming should be based on a reaction mass of the main constituents.

UVCB: Identified based on the source of the substance and process used. Any significant change in the source or process is likely to lead to identification as another substance and a separate registration. UVCB substances cannot be sufficiently described based on composition as the number of constituents is too large, the composition is, to a significant extent, unknown, or the composition is variable and poorly predictable. All known constituents and all constituents present at ≥10% should be specified in the REACH dossier, as well as any constituent relevant for classification or PBT assessment.

Sufficient analytical data to identify which of these categories a substance falls into is a must. Even for UVCB substances, analysis is key in order to ensure that representative samples are chosen for testing and to justify read across approaches, if appropriate. For UVCB substances with very large numbers of constituents, grouping of constituents can be an effective tool for managing the complexity of the substance.

Since the first registration deadline there has been increasing focus on the challenges faced by registrants with regard to substance identity. Substance identity was also a topic covered in ECHA’s 10th Stakeholders Day that took place on 27 May 2015.

As we near the next registration deadline it is important not to underestimate the work involved in confirming substance identity and the importance of this as a basis for the rest of the registration dossier.

Don’t delay in confirming your substance identity!