New research suggests that plants may suffer adverse reactions to tiny nanoparticles. While the possibility of detrimental health effects from nanotechnology has been investigated in relation to animals and humans, researchers at the New Jersey Institute of Technology have now demonstrated that plants too can be hurt by nanoparticles. A toxicology expert, professor Daniel Watts, reports that aluminum-oxide nanoparticles in groundwater inhibit the growth of all five species tested-corn, cucumber, cabbage, carrot and soybean. Watts warned that care must be taken to prevent these nanoparticles from dispersing in the air, where they will be carried by rain into groundwater systems and stunt plant growth. These concerns underscore the already accumulating evidence of possible harm to human health (see www.eet.com/ news/latest/ showArticle.jhtml?articleID=172900608) posed by nanotechnology. Nanoparticles in general may not be a problem. In Watts' tests on plants, most of the nanoparticles studied had no effect on health. In particular, silicon dioxide-a common nanoparticle-had no detrimental effect on plants. But aluminum-oxide nanoparticles slowed the growth of roots in all five vegetables tested.