Nanomaterials: a challenge for toxicological risk assessment?

Nanotechnology has emerged as one of the central technologies in the twenty-first century. This judgment becomes apparent by considering the increasing numbers of people employed in this area; the numbers of patents, of scientific publications, of products on the market; and the amounts of money invested in R&D. Prospects originating from different fields of nanoapplication seem unlimited. However, nanotechnology certainly will not be able to meet all of the ambitious expectations communicated, yet has high potential to heavily affect our daily life in the years to come. This might occur in particular in the field of consumer products, for example, by introducing nanomaterials in cosmetics, textiles, or food contact materials. Another promising area is the application of nanotechnology in medicine fueling hopes to significantly improve diagnosis and treatment of all kinds of diseases. In addition, novel technologies applying nanomaterials are expected to be instrumental in waste remediation and in the production of efficient energy storage devices and thus may help to overcome world's energy problems or to revolutionize computer and data storage technologies. In this chapter, we will focus on nanomaterials. After a brief historic and general overview, current proposals of how to define nanomaterials will be summarized. Due to general limitations, there is still no single, internationally accepted definition of the term "nanomaterial." After elaborating on the status quo and the scope of nanoanalytics and its shortcomings, the current thinking about possible hazards resulting from nanoparticulate exposures, there will be an emphasis on the requirements to be fulfilled for appropriate health risk assessment and regulation of nanomaterials. With regard to reliable risk assessments, until now there is still the remaining issue to be resolved of whether or not specific challenges and unique features exist on the nanoscale that have to be tackled and distinctively addressed, given that they substantially differ from those encountered with microsized materials or regular chemicals. Based on the current knowledge, we finally provide a proposal on how risk assessment in the nanofield could be achieved and how it might look like in the near future.