Silver nanoparticles used as antimicrobials in fabric can leach out of clothes as they are being washed. One brand lost over half of its silver content from the fabric with just two washings.
A group of Swiss scientists tested how well silver nanoparticles stayed in treated fabrics under conditions similar to a washing machine. They considered mechanical stress and chemical factors such as bleaches, pH and surfactants.
First, they measured the silver content of several different brands and types of fabrics that had silver nanoparticles either incorporated into or bound to the cotton, nylon or polyester fibers. They also included a fabric lined with a layer of silver that was not in the nanoparticle form.
They then washed the fabrics either once or twice in detergent. They added steel balls to simulate mechanical stress that would be similar to normal washing conditions. Some of the fabrics were also treated with bleaching agents during washing. These chemicals contribute the oxidants – the molecules that donate oxygen and therefore “bleach” the fabric.
The use of silver to kill microbes dates back to ancient times. However, in a modern twist, some manufacturers are adding tiny nanoparticles with silver to socks and other clothing to control odors caused by bacteria. The heavy use of silver nanoparticles has prompted questions about their human and environmental safety.
As a metal, silver is safer to people than lead, chromium and other metals. For aquatic organisms, though, the story is quite different. Silver is more toxic than most other metals to many fresh- and salt-water organisms, ranging from phytoplankton to marine invertebrates – such as oysters and snails – to different types of fish. Their immature stages are sometimes much more sensitive than adults.
[Source]
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Chapter: Home & Living ::
16 March 2010
