"Nanotechnology is rapidly expanding. However, some types of engineered nanoparticles can be toxic for living organisms and exhibit negative impact on the environment. Thus, the design of new nanomaterials must be supported by a rigorous risk analysis. Following the recommendations by the EU REACH system and regarding ethical aspects, the risk assessment procedures should be performed with possible reduction of living animal use. The main objective of the NanoPuzzles project is to create new computational methods for comprehensive modelling the relationships between the structure, properties, molecular interactions and toxicity of engineered nanoparticles. The methods will be based on the Quantitative Structure - Activity Relationship approach, chemical category formation and read-across techniques. Those methods have been widely used in risk assessment of other groups of priority chemicals. But, because of some specific reasons, they can not be applied directly to nanoparticles. We will be developing novel methods within four complimentary areas (""puzzles""), namely: (i) evaluation of physico-chemical and toxicological data available for nanoparticles (NanoDATA), (ii) developing novel descriptors of nanoparticles' structure (NanoDESC), (iii) investigating interactions of nanoparticles with biological systems (NanoINTER), and (iv) quantitative structure - activity relationships modelling (NanoQSAR). Developed methods will be tested and verified for their technical viability by the collaborating industry representative. By implementing the NanoPuzzles methods, extensive animal testing would be significantly reduced. Moreover, the project will deliver the basis for categorising nanoparticles based on potential exposure, phys-chem, structural and toxicological properties. To maximise its impact, the project is going to cooperate with ModNanoTox, NanoTransKinetics, NanoSafety Cluster and NanoMedicine ETP."