You recently ran a question about using silver in clothing as an antimicrobial. I used to be a consultant assisting a company that refined precious metals. One of its employees told me that his eyeballs were jet black because he had absorbed so much silver into his body. He was otherwise totally healthy. Can any reader confirm that silver can do this to humans, how it works and whether it conveys any harm to the individual?
鈥� There is no doubt that ingesting large amounts of silver can cause the rare but distressing condition . The skin and eyeballs of those affected turn a blue-grey colour, and there is no known cure. In most cases it is caused by taking too many silver supplements.
However, in many countries edible silver is used as a decoration on food, often called 鈥渧ark鈥� in Indian and south Asian cuisine. There don鈥檛 seem to be any adverse health effects of eating small amounts of it in this way.
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The exact mechanism for human absorption of silver is still unknown. It is suspected that substances such as thiols can form a complex with silver ions, leading to bioabsorption. There is slight concern that silver may be more readily absorbed in the form of nanoparticles.
On balance, we can conclude that ingesting tiny amounts from eating with silver utensils, say, will not lead to significant health effects. However, consuming larger amounts of silver should probably be avoided.
鈥淲e can conclude that eating from silver utensils will not lead to any significant health effects鈥�
Eric Billett, Chellaston, Derbyshire, UK