The astonishing physical and chemical properties of engineered nanomaterials have provoked an exponential growth of nanoproducts on the free market. Growing concerns over the impact of such materials on human health and the environment have initiated the first in-depth studies on the effect of nanomaterial exposure to biological systems and showed a high mobility of such materials in organisms or cells. At present a number of in vitro studies allow some limited insight in the interaction between nanoparticles and living cells. Unfortunately, few in vivo studies strongly limit our toxicological understanding of nanomaterials.

In spite of these limited available toxicological data, time and cost effective instruments are required as tools for a sustainable and safety oriented product development both in academia and industrial research. The present contribution investigates the use of physio-chemical materials properties as an easily measurable and accessible basis for a preliminary risk assessment. The possibility to classify nanomaterials based on their physical and chemical properties provides a starting point to structure the currently exponentially growing number of necessary toxicological investigations of nanomaterials.

As a first differentiation acute toxic effects from in vitro assays are urgently separated from the not acute toxic consequences of oxidative stress (ROS). Therefore the formation of ROS following exposure to nanoparticles was studied without (cell-free) or in the presence of cultured human lung epithelial cells (in vitro). Soluble salts of the corresponding heavy metals were used as reference materials.

Figure 1: Human lung fibroblast exposed to ceria nanoparticles. Scale bar 1 μm (Limbach et al 2005)

References:

L.K. Limbach, P. Wick, P. Manser, R. Grass, A. Bruinink, W.J. Stark, Exposure of Engineered Nanoparticles to Human Lung Epithelial Cells: Influence of Chemical Composition and Catalytic Activity on Oxidative Stress. Env. Sci. Technol published online (2007) DOI: 10.1021/es062629t

L.K Limbach, Y. Li, R.N. Grass, T.J. Brunner, M.A. Hintermann, M. Muller, D. Gunther, W.J Stark, Oxide nanoparticle uptake in human lung fibroblasts: Effects of particle size, agglomeration, and diffusion at low concentrations, Env. Sci. Technol 39, 9370-9376 (2005).

T.J. Brunner, P. Wick, P. Manser, P. Spohn, R.N. Grass, L.K. Limbach, A. Bruinink, W.J. Stark, In Vitro Cytotoxicity of Oxide Nanoparticles: Comparison to Asbestos, Silica, and the Effect of Particle Solubility, Env. Sci. Technol., 40 (14), 4374-81 (2006).

P. Wick, P. Manser, L.K. Limbach, U. Dettlaff-Weglikowska, F. Krumeich, S. Roth, W.J. Stark, A. Bruinink, The degree and kind of agglomeration affect carbon nanotube cytotoxicity, Toxicol. Lett., 168(2), 121-31 (2007).