Since at least the early part of the 20th century, doctors have known that silver or silver compounds can cause some areas of the skin and other body tissues to turn gray or blue-gray. Argyria occurs in people who eat or breathe in silver over a long period (several months to many years). A single exposure to a silver compound may also cause silver to be deposited in the skin and in other parts of the body; however, this is not known to be harmful. It is likely that many exposures to silver are necessary to develop argyria. Once argyria develops, it is generally believed to be permanent. The condition is not merely a "cosmetic problem". Discoloration of the skin seen in argyria is not the most serious health effect of silver. It has been shown to cause brain damage, seizures, and death or a persistent vegetative state.
Reports of cases of argyria and an EPA statement suggest that gram amounts (from 1 to 4 grams) of silver or a silver compound taken in medication in small doses over several months may cause argyria in some humans. People who work in factories that manufacture silver can also breathe in silver or its compounds. In the past, some of these workers have become argyric. However, the level of silver in the air and the length of exposure that caused argyria in these workers is not known. It is also not known what level of silver causes breathing problems, lung and throat irritation, or stomach pain in people. Studies in rats show that drinking water containing very large amounts of silver (9.8 grams of silver per U.S. gallon water or 2.6 grams per liter) is likely to be life-threatening.
Argyria that covers the entire body is not seen following skin contact with silver compounds, although the skin may change color where it touches the silver. However, many people who have used skin creams containing silver compounds such as silver nitrate and silver sulfadiazine have not reported health problems from the silver in the medicine. In one animal study, a strong solution of silver nitrate (81 milligrams silver nitrate per liter of water) applied to the skin of guinea pigs for 28 days did not cause the animals to die; however, it did cause the guinea pigs to stop gaining weight normally. It is not known if this would happen to people if they were exposed the same way.
A recent prominent case was that of Stan Jones, of Montana, a Libertarian candidate for the United States Senate in 2002 and 2006. Jones acquired argyria through consumption of a home-made silver product that he made due to fears that the Year 2000 problem would make antibiotics unavailable. The peculiar colouration of his skin was featured prominently in media coverage of his unsuccessful campaign, though Jones contends that the best-known photo was "doctored". Jones promised that he was not using his silvery complexion as a gimmick. He continues to promote the use of colloidal silver as a home remedy. He has said that his good health, minus the unusual skin tone, is the result of his use of colloidal silver.
On December 20, 2007 the world press published stories about Paul Karason, a California man whose entire skin gradually turned blue after consuming colloidal silver made by himself with distilled water, salt and silver, and using a silver salve on his face in an attempt to treat problems with his sinus, dermatitis, acid reflux, and other issues.
Another case of argyria caused by colloidal silver ingestion can be found here: PMID 17177941