Properties and Health Effects

Summary
Silver is an element found naturally in the environment. At very high levels, it may cause argyria, a blue-gray discoloration of the skin and other organs.

What is silver?
Silver is a naturally occurring element. It is found in the environment combined with other elements such as sulfide, chloride, and nitrate. Pure silver is “silver” colored, but silver nitrate and silver chloride are powdery white and silver sulfide and silver oxide are dark-gray to black. Silver is often found as a by-product during the retrieval of copper, lead, zinc, and gold ores. Silver is used to make jewelry, silverware, electronic equipment, and dental fillings. It is also used to make photographs, in brazing alloys and solders, to disinfect drinking water and water in swimming pools, and as an antibacterial agent. Silver has also been used in lozenges and chewing gum to help people stop smoking.

What happens to silver when is enters the environment?
Silver may be released into the air and water through natural processes such as the weathering of rocks. Human activities such as the processing of ores, cement manufacture, and the burning of fossil fuel may release silver into the air. It may be released into water from photographic processing. Rain may wash silver out of soil into the groundwater. Silver does not appear to concentrate to a significant extent in aquatic animals.

How might I be exposed to silver?
Breathing low levels in air. Swallowing it in food or drinking water. Carrying out activities such as jewelry-making, soldering, and photography. Using anti-smoking lozenges or other medicines containing it.

How can silver affect my health?
Exposure to high levels of silver for a long period of time may result in a condition called arygria, a blue-gray discoloration of the skin and other body tissues. Lower-level exposures to silver may also cause silver to be deposited in the skin and other parts of the body; however, this is not known to be harmful. Argyria is a permanent effect, but it appears to be a cosmetic problem that may not be otherwise harmful to health. Exposure to high levels of silver in the air has resulted in breathing problems, lung and throat irritation, and stomach pains. Skin contact with silver can cause mild allergic reactions such as rash, swelling, and inflammation in some people. Animal studies have shown that swallowing silver results in the deposit of silver in the skin. One study in mice found that the animals exposed to silver in drinking water were less active than unexposed animals. No studies are available on whether silver affects reproduction or causes developmental problems in people.

How likely is silver to cause cancer?
No studies are available on whether silver may cause cancer in people. The only available animal studies showed both positive and negative results when silver was implanted under the skin. The U.S. EPA has determined that silver is not classifiable as to human carcinogenicity.

Is there a medical test to show whether I’ve been exposed to silver?
Silver can be measured in the blood, urine, feces, and body tissues of exposed people. Silver builds up in the body, and the best way to learn if past exposure has occurred is to look for silver in samples of skin. Tests for silver are not commonly done at a doctor’s office because they require special equipment. Although doctors can find out if a person has been exposed to silver by doing these tests, they cannot tell whether any health effects will occur.

Has the federal government made recommendations to protect human health?
The U.S. EPA recommends that the concentration of silver in drinking water not exceed 0.10 milligrams per liter of water (0.10 mg/L) because of the skin discoloration that may occur. The U.S. EPA requires that spills or accidental releases of 1,000 pounds or more of silver be reported to the EPA. The Occupational Safety and Health Administration (OSHA) limits silver in workplace air to 0.01 milligrams per cubic meter (0.01 mg/m3) for an 8-hour workday, 40-hour workweek. The National Institute of Occupational Safety and Health (NIOSH) also recommends that workplace air contain no more that 0.01 mg/m3 silver. The American Conference of Governmental Industrial Hygienists (ACGIH) recommends that workplace air contain no more than 0.1 mg/m3 silver metal and 0.01 mg/m3 soluble silver compounds. The federal recommendations have been updated as of July 1999.

Glossary
Carcinogenicity: Ability to cause cancer.
CAS: Chemcial Abstracts Service.
Milligram (mg): One thousandth of a gram.
Soluble: Capable of being dissolved in water.

References
Agency for Toxic Substances and Disease Registry (ATSDR). 1990. Toxicological profile for silver. Atlanta, GA:
U.S. Department of Health and Human Services, Public Health Service.

Updated: July 1999