Risk analysis toolbox for nanoparticles
Over the last 50 years, nanotechnology and the manipulation of materials at the atomic scale has grown into a major European and global industry. Nanotechnology presence is seen in products ranging from aerospace and satellite components to consumer products and medical instrumentation. Risk assessment to ensure occupational, consumer and environmental safety is essential given that exposure to some engineered nanoparticles (ENPs) can adversely affect health. Against this backdrop, a large European consortium of experts in nanotoxicology initiated the EU-funded project 'Risk assessment of engineered nanoparticles' (ENPRA). Scientists are studying the effects of four ENPs: titanium dioxide (TiO2), zinc oxide (ZnO), silver (Ag) and multi-wall carbon nanotubes (MWCNTs). During the third project period, scientists gained important insight into the reactivity and durability of ENPs in surrogate body fluids and other media used for in vitro testing. In vitro toxicology tests were completed, including important cytotoxicity assays in epithelial cells. Variability in results across laboratories and batches of cells highlighted the need for standardisation of equipment, procedures and conditions. In vivo studies in animal models evaluated measures of toxicity in five target tissues: pulmonary, hepatic, renal, cardiovascular and developmental. ENPRA developed a mathematical model of workplace exposure to airborne ENPs based on data from collaboration with US colleagues. Scientists used a pharmacokinetic model developed previously to predict ENP distribution in various organs and determine safe air concentration levels. Data on ENP physico-chemical characteristics and dose-response data were incorporated into a quantitative structure–activity relationship (QSAR) model. This model was then applied to experimental data obtained by project partners. The ENPRA toolbox incorporated the above exposure-dose-response data and models to develop a comprehensive risk assessment toolkit. ENPRA has provided a database, standardised tools and critical mathematical models for accurate assessment of the risks of exposure to selected ENPs. The risk assessment framework will have important impact on workplace, consumer and environmental safety, as well as the development of future standards and regulatory policies.
