General background information

Silver

General background information

Silver is used in photographic materials, batteries, paints, and jewelry. Silver

is used medically in dental amalgam and in medical supplies for burn treatment.

Photographic materials are the major source of silver that is released into the

environment. Trace amounts of silver are found in water from natural sources

and industrial waste.

Pharmacokinetics

Studies in humans and animals indicate that silver compounds are absorbed

readily by the inhalation and oral routes. Individuals and individual organs

absorb silver selectively. The greatest concentrations are found in the

reticuloendothelial organs. Silver undergoes oxidation and reduction reactions

within the body and is excreted primarily via the fecal route (ATSDR 1990).

Human toxicological profile

Blue-gray discoloration of the skin has been observed in many individuals

who have ingested metallic silver and silver compounds over periods of months

to years. This condition is termed argyria. The pigmentation of the skin is

primarily in sun-exposed areas. Silver-containing granules are also observed in

the dermis. Gradual accumulation of 1 to 5 grams of silver will lead to

generalized argyria. The discoloration is not known to be diagnostic of any other

toxic effect (ATSDR 1990). Occupational exposure to silver dusts can lead to

respiratory and gastrointestinal irritation. The average air level was estimated to

range from 0.039 to 0.378 mg/m3. Duration of employment ranged from less

than 1 year to greater than 10 years. Symptoms included abdominal pain,

sneezing, stuffiness, and sore throat. Granular deposits were also observed in the

conjunctiva and corneas of the eyes (Rosenman, Moss, and Kon 1979;

Rosenman, Seixas, and Jacobs 1987). Medical case histories indicate that dermal

exposure to silver and silver compounds for extended periods of time can lead to

local skin discoloration similar in nature to the generalized pigmentation seen

after repeated oral exposure. The amount of silver and the duration of exposure

necessary to produce this effect have not been established (McMahan and

Bergfeld 1983).

Mammalian toxicological profile

Oral doses of 1,680 mg/kg silver colloid resulted in the deaths of rats after

4 days (Dequidt, Vasseur, and Gomez-Potentier (1974). Ingestion of silver

nitrate and silver chloride will also cause deposition and silver granules in the

skin of animals (Walker 1971). Granules were observed in the eyes of rats

exposed to silver nitrate in drinking water at doses of 222 mg/kg/day over

37 weeks. These doses also cause general deposition in other tissues (Matuk,

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Appendix D Toxicological Profiles