Campus News

Published by Communications and Public Affairs (519) 824-4120, Ext. 56982 or 53338

News Release

August 03, 2004

Physicist refines test for detecting silver in humans, animals

A test developed at the University of Guelph to help detect alleged “doping” cases in prize show cattle now shows promise in preventing human skin problems caused by exposure to silver.

Research by physics professor Joanne O’Meara and former undergraduate student Sean Graham on the first-ever non-invasive test for monitoring silver concentrations in skin was published this summer in Physics in Medicine and Biology. The paper also appears in the July 2004 issue of IoP Select, a special collection of Institute of Physics journal articles chosen for their novelty, significance and potential impact on future research.

“It’s an honour,” said O’Meara, who, along with Graham developed an X-ray fluorescence system for identifying silver concentrations in animals and humans. “I was really pleased that this paper was recognized by the editors as reporting on a technique with potential impact.”

Based on promising initial results, O’Meara plans further studies to identify people at risk of developing diseases caused by prolonged occupational or medical exposure to silver. Those occupations including manufacturing mirrors, making photographic chemicals and electrical apparatus, and producing alloys, coins, tableware and jewellery. She says another concern is the increasing medicinal use of silver compounds, often taken in suspension form to fight internal infections.

Prolonged exposure to high amounts of inhaled or ingested silver may cause argyria, or irreversible discolouration of the skin. Argyria causes patches or whole areas of the skin to turn slate blue, particularly exposed areas such as the face and hands. Besides these cosmetic effects, a related affliction called argyrosis may lead to discolouration of the eye and affect vision.

O’Meara says argyria is not caused by wearing jewellery or handling money, tableware or other items, although silver may be absorbed through breaks in the skin. She plans to work with clinicians to learn more about safe dosage levels of silver in humans. Monitoring skin silver levels accurately may help in altering exposure before this irreversible discolouration occurs.

At U of G, O’Meara started out measuring trace amounts of silver in animals. A fellow professor asked for help in investigating alleged silver “doping” in cattle being shown at the Royal Agricultural Winter Fair. Injecting silver under the skin causes inflammation that may make a cow’s udder appear more round and full, a trait highly prized among cattle judges. She and Graham, now a graduate student in medical physics at the University of Toronto, showed that their solid-state detector could pick up trace amounts of silver injected into samples of udder tissue. She plans to further modify her “metal detector” for use on live animals.

O’Meara came to U of G in 2002 after studying medical physics at McMaster University, where she measured depleted uranium in soldiers wounded by shrapnel in the 1991 Gulf War. She has used X-ray fluorescence to measure other trace elements in the body such as mercury, lead and cadmium.

Prof. Joanne O’Meara
Department of Physics
(519) 824-4120, 53987

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