Silver nanoparticles, valued for their antibacterial properties, are being used in a range of products, including such diverse items as socks, bandages and washing machines.

"The general public needs to be aware there are unknown risks associated with the products they buy containing nanomaterials," Arizona State University Professor Paul Westerhoff and researcher Troy Benn said, noting ordinary laundering can remove substantial amounts of the nanosilver particles from socks impregnated with the material. The scientists suggest the particles could enter waterways where they might have negative effects on aquatic organisms as well as humans.

"This is the first report of anyone looking at the release of silver from this type of manufactured clothing product," said the authors. "If you start releasing ionic silver, it is detrimental to all aquatic biota. Once the silver ions get into the gills of fish, it's a pretty efficient killer," said Benn. The toxicity of nanoparticle silver, said Westerhoff, has yet to be determined.

Westerhoff and Benn presented their findings this week in New Orleans during a national meeting of the American Chemical Society.