For the risk assessment of chemicals, toxicity data obtained in laboratory animals are required for the hazard characterization. However, there are several constraints with the use of animals for this purpose: animal studies are considered unethical, are time-consuming and expensive, and may not adequately predict the toxic responses of chemicals in humans. Therefore the development of alternative, non-animal based methods is urgently needed. Projects within this topic focus on the development of mode-of-action based alternative methods that can be applied in toxicological risk assessment. The research in this theme includes work on the translation of the in vitro data to the in vivo situation, which can be obtained with help of physiologically based kinetic modelling. Our projects focus on developmental toxicity, endocrine disruption, neurotoxicity and on the development of in vitro models for safety testing of nanoparticles.