Manufactured particulate nanomaterials (MPN) show modified or completely new properties when compared to corresponding bulk materials due to their nanoscale dimensions (Ø 1-100 nm). For this reason they are attractive for a wide range of different applications. On the one hand, the introduction of MPN promises innovation and sustainability. On the other hand, their actual health and ecological effects have to date not been proven beyond a reasonable doubt. Concerns about new health and environmental risks were voiced early by some scientists and could be verified in several cases. However, the relevance of the observed biological effects remains still unclear. In addition, nanotoxicology, which emerged from classic toxicology, has to deal with considerable methodological challenges. The existing knowledge could be denoted as "insular", therefore it is currently virtually impossible to obtain an evidence-based risk assessment of MPN. On the other hand, a valid risk assessment is a basic requirement for risk governance strategies as demanded by a number of stakeholders and parts of the general public.

The aim of the project is to systematize and map the knowledge available for a hazard assessment of selected particulate nanomaterials. This knowledge is heterogeneously distributed among persons and scientific disciplines. For this reason, a survey of the state-of-the-art in research on health effects of selected MPN will be conducted. The resulting data base will be used for the discursive evidence mapping method, which will be tested for its potential to identify and characterise the hazard of MPN (hazard assessment) and optimized, if necessary. Evidence mapping investigates conclusions of scientists with regard to concrete (e.g. toxicological) questions. It is based on a visual representation of pro and contra arguments with additional information that supports or weakens the respective argument. In addition, the discursive element (e.g. workshops or interviews) in the evidence mapping process aims at making tacit knowledge available for hazard assessment and thus should facilitate an evidence-based risk assessment.

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