The growing development, production and use of engineered nanomaterials and associated products will increase exposure of both humans and ecosystems to these new materials. However, current knowledge is still incomplete and established test methods are as yet inappropriate to reliably assess the extent of exposure and risk of materials at the nano-scale. There is an urgent need to develop methods to overcome the current limitations of existing hazard and risk assessment schemes and to generate the body of reference data needed as the basis for regulative requirements and for measures to safeguard production, application and the disposal of nanomaterials.The proposed project will mobilize the critical mass of international scientific knowledge and technical expertise required to address these questions. Current analytical and toxicity test methods and models will be put to test and subjected to rigorous intercalibration and validation. Where necessary, methods and test materials will be modified, adapted and validated, and new reliable reference methods developed, in cooperation with international standardisation bodies and the concerned industry, to support both pre and co-normative activities and to make the applicability of existing RA and LCA schemes to ENPs more reliable.The feasibility of validated measurement, characterization and test methods will be assessed by selected case studies to help the significant improvement of the performance of existing exposure monitoring systems as well as the development of new risk management and reduction strategies.