UK REACH Article 54: recommendations to registrants

General requirements

Keep contact details up to date

Registrants should ensure the contact details for their company in the Comply with UK REACH service are kept up to date – in particular email addresses, since email is the primary method of communication between HSE and registrants.

Update registration dossiers when new information becomes available

Registrants are reminded of their Article 22 obligation to keep their registration dossiers up to date (Commission Implementing Regulation (EU) 2020/1435 (legislation.gov.uk)).

HSE notes that some dossiers checked in 2025 contained details of preliminary study reports or studies that were still ongoing at the time of registration. In these situations, registrants should include in their dossier the date by which they expect to be in receipt of the final reports and provide an updated dossier containing the new information without undue delay.

IUCLID validation assistant

Registrants should use the IUCLID validation assistant to check that they have entered the required information for the relevant tonnage band in the correct sections of IUCLID.

Adaptations to standard testing

When adapting standard testing or replacing experimental values with predictions, registrants need to provide the legal basis for the adaptation and the information used to fulfil the information requirement, for example a justification document and relevant studies or documentation to support the prediction.

Minimising new tests on vertebrate animals

Registrants are reminded that, in accordance with Article 25 and Annex 6 to UK REACH, testing on vertebrate animals for the purposes of the regulation shall be undertaken only as a last resort. As such, registrants should consider alternative methods where applicable. They must also take measures to prevent duplication of vertebrate tests that have been conducted in other jurisdictions or for other regulatory purposes.

In line with Article 12 of UK REACH, registrants should include all relevant toxicological and ecotoxicological information that is available to them. This could include non-standard data and/or adaptations to the standard testing regime in accordance with Annex 11 to UK REACH to inform on toxicity endpoints.

There is guidance on how registrants can minimise testing on vertebrates when meeting the information requirements of UK REACH.

The Q(SAR) Assessment Framework is now available

(Quantitative) structure-activity relationship or (Q)SAR models are computer-based tools designed to predict properties of a substance based on its chemical structure. The OECD (Q)SAR Assessment Framework should be consulted by registrants seeking to use these models to help meet information requirements in registrations.

It’s important that the correct documentation is submitted in support of a (Q)SAR. The OECD-recommended documentation comprises:

(Q)SAR model reporting format (QMRF) to document the model (usually available from the model developer)
(Q)SAR prediction reporting format (QPRF) to document the prediction (prediction-specific, provided by the (Q)SAR user)

The latest versions of the QMRF and QPRF are included in the OECD (Q)SAR assessment framework.

There is additional guidance on the use and reporting of (Q)SARs on the ECHA website.

Robust study summaries (RSS) in registration dossiers for novel substances

Article 14(1), in conjunction with Annex 1 and Article 10(a)(vii) of UK REACH, requires the provision of RSS for information derived from the application of Annexes 7 to 10 for substances manufactured and/or imported at or above 10 tonnes per year. Annex 1 (1.1.4 & 3.1.5) describes the conditions under which RSS shall be prepared and submitted. Normally, the study or studies giving rise to the highest concern and that are used to derive conclusions in the chemical safety assessment shall be subject to RSS. However, HSE requests that RSS be provided for all studies, including those for substances manufactured and/or imported at less than 10 tonnes per year and for studies covering the physicochemical endpoints. This will facilitate any evaluation of the dossier conducted by HSE and make the task of updating the dossier more straightforward for the registrant should an increase in tonnage band be required in the future.

While information/data may be reported in wider documentation (for example risk assessments under plant protection production regulations), UK REACH registration dossiers are standalone. Therefore, RSSs should include all information necessary to demonstrate the relevance and reliability of data to meet UK REACH information requirements.

Guidance regarding the endpoint-specific information expected in RSS can be found in ECHA practical guide: How to report robust study summaries. This guidance remains valid for UK REACH when read in a GB context.

In addition, an OECD project led by ECHA has developed guidance on preparing RSS for individual information requirements; this is available on the ECHA website.

Guidance on test items used in studies

The test material used to generate the new data must be selected taking into account:

the variation in compositions reported by all members of a joint submission
the boundary composition(s) of the substance
the impact of each constituent/impurity on the test results for the endpoint to be assessed. For example, if a constituent/impurity is known to have an impact on toxicity, the selected test material must contain that constituent/impurity
if the composition of the test material deviates from that used in older studies in the dossier, suitable comparability should be clearly demonstrated

Registrants should include the following information in the dossier on the test material to demonstrate the relevance of the test item to the registered substance:

the composition of the test material selected for each study, under the 'Test material information' section, for each respective endpoint study record in IUCLID.
all constituents of each test material along with their concentration values, percentage details and other parameters relevant for the property to be tested. This information is needed to assess whether the test material is relevant for the registered substance and whether it is suitable for use by all members of the joint submission, if relevant. Technical instructions on how to report the above is available in the ECHA manual on How to prepare registration and PPORD dossiers (PDF).
test item name and identifier, for example CAS number or equivalent.
batch code or equivalent identifier.
purity details.
justification for the choice of test item if this is different from the registered substance (for example if using a transformation product, a multi-constituent substance or a substance of unknown or variable composition, complex reaction products and biological materials, that is, a UVCB).

Providing explanations for IUCLID attachments

Registrants should include a commentary in the RSS to explain what attachments represent when they are included in the IUCLID dossier.

Indicating access to data

Registrants should indicate how data have been accessed, including whether or not they are data owners, in the ‘Data source’ section of IUCLID for each SS/RSS submitted.

Apply relevant guidance for nanoform substances

Registrants should consult appropriate guidance when generating or collecting information to register nanoform substances under UK REACH. Specific appendices are available in ECHA guidance documents on how to meet information requirements and conduct chemical safety assessments.

Guidance on how to justify the use of hazard data between nanoforms and/or sets of nanoforms, and the non-nanoforms of the same substance, is available from ECHA (Appendix R.6-1 for nanoforms applicable to the Guidance on QSARs and Grouping of Chemicals).

Guidance on grouping and read-across of nanoforms has also been published by the:

Physicochemical information requirements

Some physicochemical properties are interlinked with other information requirements

Registrants should ensure consistency when the same information is included in different parts of a dossier. An explanation should be provided detailing any unexpected findings.

Toxicological information requirements

OECD Guideline 497: Defined Approaches on Skin Sensitisation can be used to meet UK REACH information requirements

Information that allows a conclusion on whether the substance is a skin sensitiser is generally required in registration dossiers for all tonnages. Registrants are reminded that the information should also enable them to conclude on the substance’s potential to produce significant sensitisation in humans (CLP Category 1A).

OECD Guideline 497 on Defined Approaches on Skin Sensitisation defines a combination of non-animal test methods (which form the standard information requirement for this endpoint in Annex 7) and computational tools to come to a rules-based conclusion on skin sensitisation hazard, potency and quantitative points of departure.

The kinetic Direct Peptide Reactivity Assay (kDPRA) is one of the methods described in OECD test guideline (TG) 442C. It can be used to identify strong skin sensitisers (CLP Category 1A). However, it cannot distinguish between other skin sensitisers (CLP Category 1B) and non-sensitisers.

The Direct Peptide Reactivity Assay (DPRA) is now applicable to UVCBs

The Annex 7 information requirement for skin sensitisation lists 3 key events that should be addressed in registration dossiers. The protein reactivity (key event 1) of substances of unknown or variable composition, complex reaction products and biological materials (UVCBs) can now be investigated in the DPRA (OECD TG 442C). The guideline now includes a gravimetric method that allows its use for UVCB substances.

Recommendations on the use of weight-of-evidence assessments for meeting the Annex 7 skin sensitisation information requirement

Where application of the DASS is not applicable fully to a substance and so cannot be used to reach a conclusion on its skin sensitisation hazard and/or potency, a weight-of-evidence approach might be possible. This approach can avoid the use of an animal test to meet the information requirement. Evidence that can be combined in a weight-of-evidence approach includes knowledge of the substance, read across and/or computational predictions for the substance or individual components of a UVCB, protein reactivity and existing animal data.

Guidance on how to carry out a weight-of-evidence approach for skin sensitisation to fulfil information requirements is available from:

Weight-of-evidence assessments should be conducted and documented in accordance with Annex 11 of UK REACH.

Meeting the information requirement for serious eye damage/eye irritation

The in vitro method described in OECD TG 492B (Reconstructed Human Cornea-like Epithelium (RHCE) Test Method for Eye Hazard Identification, June 2024) provides a full replacement of the Draize acute eye irritation test in animals.

Registrants can use this test to identify chemicals:

not requiring classification
requiring classification for eye irritation (CLP Category 2)
requiring classification for serious eye damage (CLP Category 1)

Ecotoxicological information requirements

Robust study summaries (RSS)

Registrants should include the following information in RSS to demonstrate information requirement endpoints are reliable:

Information to demonstrate how test guideline validity criteria were met.
Details of solvent concentrations and solvent controls, or state if this information is not available (if applicable).
Adequate method detail to confirm analytical measurements, including information on limits of detection/quantification and, test item identification and/or multi-constituent or UVCB substance constituent(s) where appropriate.
Endpoints based on measured rather than nominal concentrations where aquatic exposure concentrations were not stable (that is within 80 to 120% of nominal over the study period) unless otherwise justified.
Where analytical measurements reflect a limited number of test item components, or a surrogate substance, justification should be provided to support relevance to the overall test items concentrations.
Justification as to why the highest test concentration represents the maximum achievable solubility in the test medium for poorly soluble substances.
Justification regarding test item choice where the substance undergoes rapid transformation and hence the choice of test item is informed by the fate and potential ecotoxicity of the degradants/transformation products. Guidance is available in the OECD ‘Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures’.

The ECHA practical guide: How to report robust study summaries outlines what to include in an RSS.

Include information to support interpretation of ready biodegradability data

Registrants should include sufficient information to demonstrate that the 10-day window criterion has been met when studies conducted to OECD TG 301 conclude that the test item is readily biodegradable.

Information to support environmental monitoring data

If registrants include environmental monitoring data in the CSR, it would be useful to provide sufficient detail to assess the reliability and relevance of the information. For example:

analytical test method validation
sampling regime for sediment and water (frequency and sample numbers for each compartment)
quality control measures (method blanks, field blanks and procedural blanks)

Registrants might find it helpful to consider the CREED approach to characterising the data (SETAC, 2024) (PDF), on the SETAC website.

Information to support Column 2 adaptation of the activated sludge respiration inhibition test (ASRIT) (Annex 8, Section 9.1.4)

The Annex 8, Section 9.1.4 standard information requirement cannot be adapted solely on the basis of a substance being readily biodegradable. The adaptation justification should include information to consider the range of concentrations that can be expected in sewage treatment plant influent in relation to the test item concentrations applied in the ready biodegradation study.