Nano- and neurotoxicology: An emerging discipline.

The present critical review analyzes the question of how nanoparticles from continuously growing industrial production and use of nanomaterials may impact human brain health. Available evidence suggests incomplete effectiveness of protective barriers of the brain against nanoparticles translocation to the brain. This raises concerns of potential effects of manufactured nanoparticles on brain functions, given that nanoparticle's potential to induce oxidative stress, inflammation, death by apoptosis, or changes in the level of expression of certain neurotransmitters. Most concerns have not been studied sufficiently and many questions are still open: Are the findings in animals transposable to humans? What happens when exposure is chronic or protracted? What happens to the developing brain when exposure occurs in utero? Are some nanoparticles more deleterious, given their ability to alter protein conformations and aggregation? Aside from developments in nanomedicine, the evidence already available fully justifies the need to specifically evaluate the interactions between nanoparticles and the nervous system. The available data clearly indicates the need for original dedicated experimental models and tools for neurotoxicological research on the one hand, and the need for epidemiological studies of neurodegenerative diseases in manufactured nanoparticle-exposed populations, on the other. A combination of nanotoxicology with neurology in a novel discipline, with its specific tools and methods of investigation, should enable answering still unresolved questions.