Post-Congress workshop | ICCS best practice guidance workshop: application of read across in cosmetic safety assessment

This presentation will open the workshop and explain its purpose, structure, and expected outcomes. It will introduce the International Collaboration on Cosmetics Safety (ICCS) and its role in supporting the practical and transparent use of non‑animal approaches in safety assessment through the development of Best Practice Guidance. The session will highlight why read‑across remains an important tool for regulators and industry, and why clear best practice guidance is needed to support confidence and consistency.

This presentation introduces the ICCS Best Practice Guidance on read‑across. The presentation will outline the scope of the guidance and describe its key principles, including problem formulation, substance characterisation, analogue or category definition, and evaluation of uncertainty. By the end of the session, participants should understand how the guidance can support decision‑making and improve communication when applying read‑across approaches.

This session provides a focused discussion on how analogues are selected and evaluated in a read‑across assessment. It will explain the scientific criteria used to identify suitable analogues, such as structural similarity, shared functional groups, physico‑chemical properties, and similar reactivity, focussing on the use of structural similarity thresholds, and matched molecular pairing. The presentation will describe how analogue identification, screening, and evaluation follow a structured and stepwise process. The presentation aims to strengthen understanding of robust and transparent analogue evaluation before the breakout groups are introduced.

This presentation introduces a systemic toxicity case study that applies a category read‑across approach using benzoic acid. The case study demonstrates how the ICCS best practice principles can be applied in a clear and practical way. The session will explain how the category was defined and how substances were grouped using based on structural similarity, shared properties, and expected biological behaviour using both structural similarity index thresholds and Matched Molecular Pairing. It will describe how available data were identified, screened, and evaluated, and how uncertainty was considered. By presenting a concrete and well‑documented example, this session aims to help participants better understand how category read‑across can be applied in real regulatory contexts and how such approaches can support confident, science‑based safety assessments.