Silver - Toxicology of Metals - page 792

2005), corresponding to approximately 19,600 metric
tons. The estimated United States mining production
for 2004 was 1200 metric tons (U.S. Geologic Survey).
Mexico, Peru, Australia, China, and Poland were the
top fi ve silver mining countries in 2004 (The Silver
Institute, 2005).

1972). Molluscs collected from coastal areas of the
North Sea have been reported to contain silver concen-
trations of up to 2.0 mg/kg (Dutton et al ., 1973; Segar
et al ., 1971). Drinking water, not treated with silver for
disinfection purposes, usually contains extremely low
concentrations of silver. A range of nondetectable to
5 g/L was reported for 380 fi nished waters, waters

that have been treated and are ready to be delivered to
consumers, from the U.S. sources (Carson and Smith,
1975). Treated waters may contain 50

µ

3.2 Uses
The primary use of silver is in industrial applications.
The industrial applications include electrical applica-
tions, particularly as conductors, switches, and con-
tacts; plating applications; silver brazing or soldering;
and miscellaneous uses such as mirrors, batteries, catal-
yses in chemical reactions, and as bactericide and algae-
cide. The second most important use is the production
of coins, jewelry, and tableware. Silver is extensively
used in photographic processing, with the radiographic
market being the most signifi cant market followed by
the consumer market (The Silver Institute, 2005). Silver
salts are also used as disinfectants. Recently, production
of silver nanoparticles has been started for application
in various nanotechnologies, incorporation into fi bers
(Reip, 2005), and suggested as antibacterial agent in
bone cement for use in arthroplasty (Alt et al., 2004).

g/L or even
slightly higher concentrations (Just and Szniolis, 1936).
The U.S. Environmental Protection Agency has set the
drinking water standard, the maximum contaminant
level, at 0.1 mg/L (US EPA). Typical background lev-
els found in rivers of the United States are 1-2 ng/L
(Shafer et al ., 1998). Concentrations of 5-150

µ

g/L have
been reported in sewage sludge (Berrow and Webber,
1972) and 28-8

µ

g/g dry wt. in Stockholm 1995-2005.
Soil concentrations of silver vary greatly by geologi-
cal area (Wells and Elliott, 1971). Granite igneous rock in
Nevada has been reported to contain up to 50 mg/kg Ag.
Coal fl y-ash has been reported to contain up to
15 mg/kg Ag (Headlee and Hunter, 1953), and emis-
sion of silver from coal-fi red power plants may lead to
its accumulation in soil of adjacent areas.
Silver has been measured in air as a result of anthropo-
genic actixzxvity. Air concentrations of silver over south-
ern California have been reported to be approximately
2 ng/m 3 (Bruland et al ., 1974). The emission of silver iodide
crystals during cloud seeding has been estimated to result
in a silver concentration in air of approximately 0.1 ng/m 3
(Sargent, 1969; Standler and Vonnegut, 1972). Silver con-
centrations in rainwater as a result of this process were
estimated to be between 0.04 pg/mL and 5 ng/mL.

µ

4 ENVIRONMENTAL LEVELS
AND EXPOSURES

4.1 General Environment
4.1.1 Food and Daily Intake

A detailed mapping of various dietary sources of silver
is not available. Silver may be ingested through consump-
tion of marine organisms containing low concentrations
(see later) and in small amounts released from dental fi ll-
ings (Leirskar, 1974) and eating utensils (Harvey, 1970).
Tipton et al . (1966) found that two subjects had ingested
between 10 and 20

4.1.3 Tobacco

Concentrations of silver in cigarettes are low.
Because of its high boiling point, most of the silver in
cigarettes is probably not inhaled.

g/day from food during a 30-day
period. Wester (1971), by NAA, found a daily intake from
food of 1-16

µ

g. US EPA estimates silver intake from diet
ranged from 10-44

µ

5 METABOLISM

µ g/day (US EPA, 1980).

5.1 Absorption

4.1.2 Water, Soil, and Ambient Air

5.1.1 Inhalation

Seawater has been reported to contain silver con-
centrations of 0.055-1.5

m spherical sil-
ver particles in the lungs of dogs has been found to
be approximately 17% (Phalen and Morrow, 1973).
Newton and Holmes (1966) studied the long-term
retention in a human subject who had accidentally
inhaled radioactive silver (chemical form not known).
Their data indicated that the liver uptake was maximal

The deposition fraction of 0.5 µ

g/L (Schutz and Turekian,
1965). Much higher concentrations (0.03 mg/L) have
been reported in wastewater effl uents entering south-
ern California coastal basins (Bruland et al ., 1974; Gal-
loway, 1972; Young et al ., 1973). Silver has also been
reported at concentrations of 14-20 mg/kg in bottom
sediments in these areas (Bruland et al ., 1974; Galloway,

µ