Nanomaterials, the current darlings of industry, are showing up in products ranging from cosmetics to electronics. However, new animal studies indicate that inhaling these microscopic spheres and tubes could cause big trouble, especially for workers who manufacture and handle them. That message came through loudly in New Orleans last week at the Society of Toxicology meeting, where several dozen reports unveiled details about how nanopollutants interact with the body. Most of the studies focused on the effects of lung exposures because the particles' size-just a few billionths of a meter in diameter-permits them to reach the most vulnerable lung tissue. John T. James of NASA's Johnson Space Center in Houston, and his colleagues squirted nanoparticles into the respiratory tracts of mice and then examined the rodents after 1 week and after 3 months. Although sootlike carbon nanospheres caused no harm, an equal mass of commercially available carbon nanotubes wreaked significant lung damage, even killing a few animals.