Palladium - Toxicology of Metals - page 744

but there was increasing use of palladium catalysts
to meet the hydrocarbon limits imposed by low-emis-
sion-vehicle legislation.
Palladium is used in jewelry and coinage. In the
fabrication of jewelry in Japan, palladium is a subsidi-
ary alloying component of the platinum alloys used
(Coombes, 1990). From recent case reports (Bircher and
Stern, 2001; Suhonen and Kanerva, 2001) the “titanium”
spectacle frames that actually consist of palladium can
cause contact allergies. Alloys are also used for bear-
ings, springs, and balance wheels in watches and for
mirrors in astronomical instruments.
Because palladium has a strong catalytic activ-
ity for hydrogenation, dehydrogenation, oxidation,
and hydrogenolysis reactions, palladium compounds
are used as catalysts for chemical processes in many
industries.
The following list summarizes the uses of some
important palladium compounds (IPCS, 2002a):
1. Ammine complexes of palladium: industrial
separation of palladium, electroless plating,
and bright palladium plating. Ammonium
hexachloropalladate(IV) is important in
separation technology.
2. Palladium(II) acetate: preparative chemistry.
3. Palladium(II) chloride: plating baths, photog-
raphy, toning solutions, electroplating parts of
clocks and watches, detecting carbon monox-
ide leaks in buried gas pipes, manufacture of
indelible ink, the preparation of catalysts, and
medical use.
4. Palladium(II) nitrate: a catalyst in organic
syntheses, and for the separation of chlorine
and iodine.
5. Palladium(II) oxide: a hydrogenation catalyst in
the synthesis of organic compounds
6. Hydrogen tetrachloropalladate(II): palladium
preparation.
7. Tetraammine palladium hydrogen carbonate: an
intermediate in the production of automobile
catalysts.

been reported: 0.4 ±0.1 ng Pd/L in Idaho (Shah and
Wai, 1985); 1.0 ± 0.1 ng/L (Schwarzbach river) and
0.4 ± 0.1 ng/L (Rhine River) in Germany (Eller et al .,
1989); and 1-2 ng/L in the lakes of Canada (Hall and
Pelchat, 1993).
For spring water samples, the values are some-
what or considerably higher: 3 ng/L in water sam-
ples from springs in Nevada (Stetzenbach et al ., 1994),
22 ng/L in Osaka, Japan (Chikuma et al ., 1991), and
0.1

g/L in the People's Republic of China (Zhou
and Liu, 1997).
The palladium concentrations in rain collected in
Stuttgart, Germany, were at levels below the detection
limit of 5 ng/L (Helmers et al ., 1998).
In seawater, palladium concentrations of 22 pg/
L (depth, <10 m) and 60 pg/L (depth, 3000 m) were
found in fi ltered samples of Pacifi c Ocean water (Gold-
berg, 1987). The palladium concentration in the water
column of the northeast Pacifi c Ocean increased from
19 pg/kg at the surface to 70 pg/kg in deep waters
(Lee, 1983).
It has been reported that the palladium concentration
in the soil of an area with high traffi c density in Cali-
fornia was below the detection limit (0.7

µ

g/kg) of the
AAS used (Johnson et al ., 1976). There have been two
reports concerning the increased palladium concentra-
tions along the autobahn near Frankfurt, Germany. Sam-
ples taken in 1990 and 1991 gave a mean value of 2

µ

g
Pd/kg (Zereini et al ., 1993). More recent samples (1994)
gave a mean value of 6

µ

g Pd/kg (Zereini et al ., 1997).
It was suggested that the elevated level was due to the
increased use of catalytic converters in automobiles.
The data on palladium concentrations in the surface
soil near a palladium production site are extremely
scarce. The palladium concentration in the area around
a platinum-group metal mine (Sudbury, Ontario, Can-
ada) was determined to be 2.0-4.5

µ

µ g/kg (Johnson

et al ., 1976).
Although there are very few data on palladium con-
centrations in the atmosphere, these values are quite
variable. Before the introduction of automobile cata-
lytic converters, the palladium concentrations in an
area in California were reported to be below the detec-
tion limit (0.06 pg Pd/m 3 ) despite the high traffi c den-
sity (Johnson et al ., 1976). In the 1990s, the palladium
concentrations in aerosols were determined in differ-
ent places. In Imperial County, California, the level
of PM10 (particulate matter having an aerodynamic
diameter below 10 micrometers) was 52.2

4 ENVIRONMENTAL LEVELS AND
EXPOSURES

4.1 Water, Soil, and Ambient Air
Water samples collected from streams and ponds
in and around the mining and ore processing facili-
ties located in Sudbury, Ontario (Canada), were below
the detection limit of 15 ng Pd/L (Johnson et al ., 1976).
Although the detection limits vary, concentrations of
palladium in the ng/L range in natural waters have

g/m 3 , with
the average palladium concentration <1 pg/m 3 (Lu et
al ., 1994). At Caesarea, Israel, Gertler (1994) observed
an averaged PM2.5 concentration of 25.5

µ

g/m 3 with a
palladium average concentration of 3.3 pg/m 3 . In con-
trast, in the city of Chernivtsi, Ukraine, the levels of

µ