
Silver
Very large doses of silver can cause an unsightly condition known as argyria which causes the sufferer's skin to turn a purple or purple-grey colour. In smaller doses, it is not thought to be a particularly toxic element. It is used widely in domestic water filters to prevent bacterial growth. It is, therefore, a good idea to reject the first draw of water from these units when a new cartridge is fitted in case any loosely bound silver is liberated and enters into the drinking water.