Swedish researchers say clothing treated with silver poses a toxic threat to sediment-dwelling creatures and organisms in lakes and seas. They analysed sportswear garments treated with silver and found that up to 90 per cent of the silver contained was washed away from the clothing after just ten machine washes. The research says the spread of silver in the environment may be contributing to the rise in antimicrobial resistance.

While known for its antibacterial qualities, silver is also classified as a biocide by the European Union.

Antibacterial silver leaching from treated textiles is now the largest known source of silver in effluent treatment plants. Silver in ionic form is hazardous to bacteria and aquatic organisms and can cause particular harm to organisms living on the bottoms of lakes and oceans such as crustaceans. Of the most common biocides found in nature, silver tops the list.

After ten washes the amount of silver leached from silver-treated clothing ranges from 31 per cent to 90 per cent, with the median amount being 71 per cent. Several clothing brands are unable to state which active biocides are used to treat their anti-odor sportswear. Nine out of 15 garments labeled in some way as anti-odor contain silver.