A roadmap for animal-free chemical testing
For many years, the European Union has pursued a policy aimed at the replacement, reduction and refinement of animal testing (the 3Rs principle). To put the ethical principle of the 3Rs into practice, the European Commission has published a roadmap for the gradual phaseout of animal testing in the safety assessment of chemicals.
This article explores the European Union's roadmap for transitioning away from animal testing in the assessment of chemical safety, known as the 3Rs principle. The central tool in this effort is the ASPA (Alternative Safety Profiling Algorithm) workflow, a structured, transparent, and reproducible method for conducting fully animal-free risk assessments.
Developed by the ASPIS cluster, which includes projects ONTOX, PrecisionTox and RISK-HUNT3R, the ASPA workflow integrates biological activity data from new approach methodologies (NAMs), human exposure and uptake information, and toxicological mechanisms to assess chemical risks. The workflow consists of around 55 assessment elements, providing a multistage, modular strategy for risk analysis.
Key components of the ASPA workflow include toxicokinetic PBK (physiologically based kinetic) models, which translate in vitro test results into realistic human exposure scenarios. These models, developed by researchers at Fraunhofer ITEM, focus on inhalable substances and calculate processes such as absorption, distribution, metabolism, and excretion (ADME) based on anatomical and physiological data.
Case studies, like the OECD IATA project, demonstrate the practical application of ASPA and the in vitro and in silico models. By combining high-throughput in vitro assays with biokinetic modeling and machine learning, researchers can identify substances with potential systemic toxicity at an early stage and prioritize them for further assessment.
This high-dimensional data helps systematically evaluate changes at the cellular and molecular levels, identifying the most predictive features for detecting potentially toxic substances.
The European Commission is integrating these methods and concepts into regulatory decision-making, recognizing that while an immediate ban on animal testing is not feasible, a coordinated regulatory transition is crucial. Many new approach methodologies have advanced significantly, but regulatory acceptance remains a challenge. Fraunhofer ITEM continues to validate these models to ensure their acceptance and integration into regulatory processes.
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