Exposure to silver can cause argyria, in which the skin turns a grey-blue color as a result of deposits in the dermis of metallic silver and silver compounds. Unlike the orange coloration that eating too many carrots can cause, the dark grey cast of argyria is permanent. The condition can be striking if the entire body is affected. Barnum & Bailey's Blue Man was found at autopsy to have argyria, perhaps from exposure while working as a silver miner: a real blue color worker.
Argyria in this century is more likely a result of exposure to quantities of silver in non-industrial settings. Silver preparations were used pharmaceutically in the early 20th century, and much of the literature about silver and skin discoloration dates to that time. There are reports of cases of argyria
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The photo is of Rosemary Jacobs, who suffers from argyria, and is used with her permission. In 2006, Stan Jones, ran as the Libertarian candidate for U.S. Senate in Montana. He took a colloidal silver compound in 1999 and now has argyria as a result.