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ECHA Releases New Practical Guide on How to Address Specific Substance Identification Issues: Evaluation of Different Crystalline Forms
On June 22, 2010, the European Chemicals Agency (ECHA) announced that a new practical guide makes clear that inorganic substances with the same chemical composition but different crystalline forms are regarded as different substances under the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) regulation (EC No. 1907/2006). Practical guide 11: How to address specific substance identification issues (Practical Guide) is available online.
The assessment of substance identity is part of the evaluation process carried out by ECHA after registration. The information presented in the Practical Guide explains the approach ECHA will adopt in evaluating the identity of inorganic substances, helping potential registrants to prepare their registration dossiers. The Practical Guide will be updated whenever ECHA becomes aware of issues that would benefit from specific, targeted advice of this kind. Registrants are advised to take note of this Practical Guide when preparing their registration dossiers to ensure compliance under REACH.
Practical Guide 11 on Substance Identification
The purpose of the Practical Guide is to provide information to potential registrants on specific issues relevant to the identification of substances according to the requirements of REACH, available online, and the Regulation on Classification, Labeling and Packaging of Substances and Mixtures (CLP) (EC No 1272/2008), available online.
The Practical Guide is aimed at manufacturers and importers of substances, including their Only Representatives, and their expert advisors, especially those responsible for submitting data on substance identity. This is also an invaluable guidance for exporters to the European Union (EU) who need to verify that companies importing their products into the EU are in compliance with REACH and CLP.
Inorganic Substance Identification — Different Crystalline Forms
An assessment of substance identity is part of the evaluation process carried out by ECHA, therefore, the guidance presented in the Practical Guide will help in ensuring substances are registered correctly.
Under REACH, registrants have the primary responsibility for the naming and identification of their substances and the guidance in the Practical Guide will make clear that if there are different crystal forms of an inorganic substance with the same chemical composition, these forms are regarded as different substances under REACH.
ECHA has become aware that there is uncertainty among some registrants about their REACH obligations with respect to the different crystalline forms of inorganic chemicals, in particular whether to register them as different substances or to have one single registration covering all crystalline forms.
ECHA’s Guidance for identification and naming of substances under REACH, available online, states in Section 4.2.3 that: “Some substances (e.g., inorganic materials) which can be identified by their chemical composition need to be further specified by additional identifiers to get their own substance identification.”
Section 4.2.3.2 details identifiers of these types of substances. These substances are identified and named according to the rules for mono- or multi-constituent substances with other specific main identification parameters added depending on the substance in question. Examples of other main identifiers can be elemental composition with spectral data, the crystalline structure as revealed by X-ray diffraction (XRD), Infra Red absorption peaks, swelling index, cation exchange capacity, or other physical and chemical properties.
Under Section 8.2.3 of the Guidance for identification and naming of substances under REACH, details are given on how the substance identity information for a “[s]ubstance defined by its chemical composition plus other identifiers” should be included in the IUCLID dossier. It is clearly stated that the crystalline structure should be included in Section 1.1 of the IUCLID dossier for minerals as it is required for their identification.
Thus, it is implicit from this guidance document that inorganic substances with different crystal structures are different substances under REACH.
ECHA Advice to Registrants of Inorganic Substances
The following advice is provided to registrants in the Practical Guide:
- Where an inorganic substance of defined crystallinity (including if known to be in non-crystalline amorphous form) is manufactured, ECHA expects registrants to register that specific substance, with the substance name specifying the crystalline form and with the appropriate analytical information to confirm the structure for that specific substance provided in the dossier. For example, when specific crystalline forms of silicon dioxide (e.g., amorphous, quartz, cristabolite, etc.) or titanium dioxide (anatase, rutile, brookite) are manufactured, the registrants should register each of these distinct crystalline forms as different substances in their own right (e.g., amorphous silica should be registered and not “silica”; anatase should be registered and not “titanium dioxide”).
- Where a manufacturing process results in an inorganic substance consisting of a mixture of different crystalline constituents, the substance should be considered as a multi-constituent or an Unknown, of Variable Composition, or of Biological Origin (UVCB) substance, depending on the variability in substance composition. An example of a multi-constituent substance would be one where the substance composition is controlled and the concentration of each constituent can be precisely defined, e.g., a substance consisting of a mixture of 75% w/w anatase and 25% w/w rutile would be identified as “Reaction mass of anatase and rutile titanium dioxide.” The mineral name can also be used as the substance name, e.g., “apatite” refers to a multi-constituent substance with hydroxylapatite, fluorapatite, chlorapatite and bromapatite as components. If the composition is not precisely known or controlled, the substance would be a UVCB substance, and may in addition be defined by the starting materials and the process of production or by the resulting composition. An example of a UVCB substance would be bentonite. While some variability in composition of UVCB substances from different producers is to be expected, registrants using different starting materials and/or different manufacturing processes need to demonstrate with appropriate information and justification in the registration dossier that they nevertheless produce the same substance. Evidence of the comparable crystallinity of the constituents can be a key factor in determining whether the same UVCB substance is produced, or if instead there are different substances.
- The registration dossiers for each of the different crystal forms must provide all the necessary information on the properties of that form at that tonnage band, as specified in the Annexes to the REACH regulation. Since different crystal forms may exhibit different hazardous properties, it is very important for the registrant to document for each form the relevant form-specific properties in the registration dossier. In particular, the test data submitted should make clear which form was used in the test reported. In the interests of minimizing animal testing, REACH allows the use of adaptations to information requirements (Annex XI or Column 2 of the Annexes VII to X of the regulation). Where such adaptations, including “read-across,” are used, a transparent and scientifically sound justification has to be included.
Further Information
Other relevant resources include: