DATA STRATEGY FOR UVCBS

Developing a data strategy for UVCB (Unknown or Variable composition, Complex reaction products or biological materials) substances is a critical part of REACH compliance. REACH requires data sharing between registrants of the same substance to avoid unnecessary testing, especially involving vertebrate animals.

In practice, this involves:

• Participation in joint submissions
• Data sharing across registrations via Letter of Access
• Assessment of data in terms of transparency, fairness involving Klimisch scoring
• Collaborating with stakeholders including co-registrants

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Core Challenge

The primary challenge was to establish a registration pathway for substances with consideration for:

• complex and variable composition
• often novel material
• limited substance-specific datasets
• identifying a lead registrant or a consortium is often only feasible after an inquiry dossier is completed
• data gaps across required REACH endpoints (toxicology, ecotoxicology and environmental fate, physical chemistry etc) need to be assessed
• Annual tonnage needs to be estimated
• Data endpoint mapping against the tonnage band
• Evaluation of whether reliance on read-across and alternative approaches is appropriate and for which endpoints
• Data waivers and scienctific justification assessment where applicable  
• constraints relating to timelines
• study costs

This required coordination across multiple technical and regulatory elements, where decisions in one area directly affected outcomes in others.

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Approach

A structured and integrated data strategy programme was implemented to support REACH registration requirements for UVCB substances involving a thorough data gap analysis, data sharing, stakeholder engagement and ongoing study commissioning.

READ ACROSS

In areas where data is lacking, read across can be used to predict properties of similar compounds. However, this can be particularly challenging for UVCBs. Meanwhile, ECHA has tightened expectations in recent guidance and now requires:

• Clear justification of similarity
• Relevance-based constituents or structural feature identification
• A well-documented scientific hypothesis

For UVCBs, read across will frequently work using constituent-based or source-based approaches supported by compositional and analytical data. Weak or poorly justified read-across is a frequent source of regulatory challenge.

WEIGHT OF EVIDENCE

In cases where no single study is sufficient, a weight-of-evidence approach may be applied. This involves combining multiple data sources to support hazard conclusions, including:

• Experimental data
• Literature studies
• Analogue data

All conclusions must be scientifically justified and transparent, in line with REACH Annex XI requirements.

New Approach Methodologies (NAMs)

There is increasing regulatory support for New Approach Methodologies (NAMs), which reduce reliance on animal testing. These include:

• in vitro methods
• in silico models (e.g. QSAR)
• mechanistic approaches

For UVCBs, NAMs can be useful, but they need to be applied carefully and supported with strong justification due to the complexity of these substances in close alignment with their OECD study counterparts.

DATA GAP ANALYSIS AND STUDY STRATEGY

A data gap analysis is used to identify what information is missing for the relevant REACH tonnage band.

This helps determine whether:

• existing data can be used
• data adaptation approaches are suitable
• new studies need to be commissioned

If new studies are required, they must follow recognised guidelines (e.g. OECD). Timelines and costs need to be carefully managed.

DATA QUALITY AND EVALUATION

Not all data is equal. Studies must be assessed for reliability using approaches such as Klimisch scoring, which looks at how trustworthy and relevant the data is Benchmarking against similar substances can also help strengthen the overall data package and assessment in terms of the Letter of Access costs.

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Outcome

• Structured data strategies established for UVCB registration programmes
• Data sharing approaches aligned with REACH requirements
• Read-across and weight-of-evidence strategies developed and justified
• Data gaps identified and addressed through defined study strategies
• NAMs and alternative methodologies evaluated where appropriate
• Data quality assessed using recognised evaluation approaches
• Registration data packages developed to support REACH compliance

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Key Consideration

For UVCB substances, data strategy extends beyond generation of individual studies. Effective REACH compliance requires integration of data sharing, scientific justification, data quality assessment and regulatory expectations within a structured and defensible framework.