Advanced human-relevant in vitro and in silico toxicology approaches as alternatives to animal testing

Background Traditional toxicological testing has relied heavily on animal models to assess chemical and pharmaceutical safety. However, species-specific differences, ethical concerns, high costs and limited predictive value for human outcomes have highlighted the urgent need for more human-relevant testing strategies. Objectives This review aims to present the scientific foundation and recent advancements in in vitro and in silico toxicology platforms that offer human-relevant, ethical and cost-effective alternatives to animal testing. Methods The paper synthesizes current literature and case studies related to innovative in vitro models (e.g., organoids, organ-on-a-chip systems) and in silico approaches (e.g., QSAR models, PBPK modeling, machine learning and systems toxicology). It also examines their integration within regulatory frameworks and evaluates their readiness for regulatory adoption. Results Emerging in vitro systems have demonstrated enhanced physiological relevance and predictive accuracy for human responses. Simultaneously, in silico models offer robust tools for data integration, exposure modeling and toxicity prediction. When combined, these platforms support Integrated Approaches to Testing and Assessment (IATA), aligning with the 3Rs (Replacement, Reduction and Refinement) and advancing mechanistic understanding through Adverse Outcome Pathways (AOPs). Several regulatory agencies have begun accepting data from these platforms, though full integration remains limited by validation and standardization challenges. Conclusions Human-relevant in vitro and in silico platforms represent a transformative shift in toxicology. They represent promising and increasingly valuable complementary approaches that may substantially reduce reliance on animal testing; however, continued validation, standardization and regulatory acceptance remain essential before widespread replacement can be achieved. Continued development, validation and regulatory harmonization are essential to fully realize their potential and establish a new paradigm in safety science.