Current toxicological findings indicate that the "rigidity" of inhalable biopersistent advanced materials like carbon nanotubes and -fibres can be essential for their carcinogenicity. The project intends to develop and assess two different approaches for measuring the bending stiffness of fibres. It aims at studying a rigidity-related risk characterisation of fibrous advanced materials. The first approach is based on a scanning electron microscopic determination of the Young's modulus by analysis of the vibration characteristics of single-side fixed fibres using electrostatic or piezoelectric excitation. The second method is based on the analysis of the curvature distribution statistics of nanofibre ensembles. It requires a software-assisted analysis of scanning electron micrographs of nanofibre ensembles that were precipitated from the aerosol state. It is expected that for some fibre types carful control of the preparative conditions will allow studying correlations between the measured rigidity and the curvature distribution of a fibre ensemble. Both, the necessary technical requirements and the reliability of the test methods to be developed will be assessed with respect to their future implementation in the legal European framework for chemical safety. The project results are expected to lay the foundation for a systematic evaluation of already completed or still to be initiated animal studies on the toxicity of fibrous materials with respect to correlations between toxicity and fibre morphology, biopersistence and rigidity.
Unit 4.5 "Particulate Hazardous Substances, Advanced Materials"