* 13 August 2010 by Helen Knight
* Magazine issue 2773. Subscribe and save
* For similar stories, visit the Nanotechnology Topic Guide
ANTIBACTERIAL nanoparticles may have more of an impact on the environment than we thought, including potentially raising levels of greenhouse gases.
Silver nanoparticles are used as an antibacterial agent in a wide range of products, from odour-free socks to wound-healing bandages (see diagram). They can find their way into waste water, and have been shown to reduce the activity of bacteria used to remove ammonia when the water is treated.
So far most of the research on the environmental impact of nanoparticles has been carried out on single microbe or plant species within the laboratory. To try to pin down their action in a more realistic setting, Benjamin Colman, a chemist at Duke University in Durham, North Carolina, and colleagues added a high dose of silver nanoparticles - 1.25 milligrams per gram of water - to microbes in a sample of stream water and soil kept within their laboratory. They also set up two outdoor tubs of plants. Treated sludge known to be free of nanoparticles was added to the soil in both tubs, while one tub was also dosed with 55 micrograms of silver nanoparticles per gram of sludge, a concentration similar to levels often found in waste water.
"We are trying to find out what happens when these silver nanoparticles get into the real environment," says Colman. "These particles are developed with the express purpose of killing things."
to read more: http://www.newscientist.com/article/mg20727735.300-antibacterial-socks-may-boost-greenhouse-emissions.html