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 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 used silver nanoparticles.
They then washed the fabrics in detergent, later adding 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.
When the fabrics were washed in water with detergent only, the silver generally stayed in the fabrics. However, several fabrics released silver quite readily once the steel balls were added to mimic mechanical actions of the washing machine.
Of the seven nanoparticle fabrics subjected to mechanical stress, four lost roughly 20 percent to 35 percent of their silver with the first wash.