Andrew Chung, The Toronto Star
May 18, 2008 04:30 AM
For as long as there have been socks, there have been smelly socks, and attempts to try to solve that eternal, noxious problem.
For the last few years, a type of sock has become very popular because it has the solution built right in: infinitesimal particles of silver, naturally anti-bacterial and, thus, anti-odiferous.
The silver, known since ancient times to have disinfectant properties, works so well because particles so small can be vastly more powerful than the same substance at normal size.
It’s hard to overstate just how small. “Nano” means one-billionth of a metre. In many cases, this refers to the scale of atoms, which are the smallest units of all matter.
A human hair, by comparison, is 80,000 nanometres wide.
But what happens to the particles in the socks? In an experiment reported at the American Chemical Society meeting last month, two Arizona State University scientists, Troy Benn and Paul Westerhoff, washed seven brands of nanosilver socks and then tested the wastewater. All but one pair leaked silver.
That silver, of course, ends up in our sewers, rivers and lakes.
The most prevalent nanoparticle product contains nanosilver. Over 60 per cent are “health and fitness” products, according to the project, an initiative of Woodrow Wilson International Center for Scholars.
You can find nanosilver in products from clothing and shoes to mattresses and pillows to appliances like Samsung’s SilverCare washers, and Conair’s Infiniti Nano Silver hair straighteners. The TTC also intends to paint the stanchions in its new subway cars with antimicrobial silver.
Friends of the Earth found more than 100 nanomaterials in food and food packaging, including Miller beer bottles that have nano clay, making them less likely to shatter.
Titanium dioxide is found in sunscreens. Fullerenes and alumina nanopowders in cosmetics. Zinc oxide in food additives.
These new uses for nanomaterials have some scientists worried.
“The new controversy is, should it be incorporated into sweatshirts and shoes?” wonders Kevin Robbie, a physics professor at Queen’s University in Kingston and the Canada Research Chair in Nanostructured Materials. “Generally it’s not a very good idea.”
Last December, in the journal Biointerphases , Robbie and two researchers published a comprehensive review of nanoparticle toxicity, mostly to ensure they understood the risks of the materials they work with every day. As a result, they have tightened their cleaning procedures and now store their nanoparticles in fluid, to prevent them from becoming airborne.
The problem is that little is known about how nano-sized elements will act in living organisms and the environment.