Evaluation of health risks of technical nanoparticles - the contribution of characterization
According to ISO/TC 229, nanomaterials represent structures whose units are usually smaller than 100 nm. In order to recognize size-related risks of these new materials early, toxicological studies have to be conducted at nanoparticles. A relevant assessment for the interpretation of toxicological examinations requires the comprehensive chemical-physical characterization of the used powders. In order to quantify the changes of the particle properties in physiological media, the agglomeration behaviour of the particles as well as the interactions with proteins, which are a main element of body fluids, have to be evaluated. Results for nanosized particles like ceramic powders (Al2O3, TiO2) and hardmetals (WC, WC-Co) are presented. Based on data of the powders, which include the analysis of crystal structure, the determination of the chemical composition, the particle and agglomerate size as well as the specific surface a stable suspension will be developed. For this, zeta potential measurements are utilized to quantify the effect of different non-toxic dispersant aids. Energy input by ultrasound is used for deagglomeration. This procedure leads to a suspension, which contains "smallest dispersable units" of a powder and which might be exposed to cultural media. Finally the effect of proteins as dispersant aids in these media is shown.