In 2004 Günter Oberdörster and colleagues published a seminal review on the emerging discipline of nanotoxicology, which was later selected as EHP's 2008 Paper of the Year. In this podcast, Oberdörster tells why nanomaterials are so different from their larger chemical counterparts and describes the growing use of these materials in consumer products. Oberdörster is a professor in the Department of Environmental Medicine at the University of Rochester, New York, and director of the University of Rochester Ultrafine Particle Center. Visit the podcast webpage to download the full transcript of this podcast.