Challenges in assessing nanomaterial toxicology: a personal perspective.

Nanotechnology exploits the fact that nanoparticles exhibit unique physicochemical properties, which are distinct from fine-sized particles of the same composition. It follows that nanoparticles may also express distinct bioactivity and unique interactions with biological systems. Therefore, it is essential to assess the potential health risks of exposure to nanoparticles to allow development and implementation of prevention measures. Risk assessment requires data concerning hazard and exposure. Several challenges face the field of nanotoxicology in obtaining the necessary data for assessment of the bioactivity of nanoparticles. They include: (1) the vast number of nanoparticle types to be evaluated, (2) the need to use nanoparticle doses and structure sizes in cellular and animal test systems which are relevant to anticipated workplace exposures, and (3) artifactual in vitro results due to absorption of nutrients or assay indicator compounds from the culture media. This 'opinion' reviews the progress made in the field of nanotoxicology in recent years to overcome these challenges.