Gallium and Semiconductor Compounds - Toxicology of Metals - page 536

World Production of Gallium (metric tons)
1973 2002

−

100.0

World production

90.0

80.0

70.0

60.0

50.0

40.0

30.0

20.0

10.0

0.0

Year

FIGURE 1

World Production of Gallium (metric tons) from 1973-2002.

Gallium isotopes such as 67 Ga are widely used for organ
screening (e.g., Hodgkin's disease and lymphomas)
(Foo et al ., 2004; Friedberg et al ., 2004; Galanski et al .,
2003, Kellenberger et al ., 2004; Ng et al ., 2005; Shah Sayed
et al ., 2004; Tuli et al ., 2004) and receptor-based nononco-
logical diseases (Sosabowsky et al ., 2003). These include
infections (Love and Palestro, 2004), and sarcoidosis
(Abad et al ., 2004; Nakazawa et al ., 2004). The uptake of
67 Ga into tumor cells has been reported to be stimulated
by hypoxia related to tumor cell transferrin recep-
tors, because Ga binding to transferrin was not altered
under hypoxic conditions (Kinuya et al ., 2004). Gal-
lium nitrate has received expanded use as an antitumor
agent for tumors of the bladder and lymphatic system
(Chitambar, 2004a). Gallium exerts part of its effect by
means of competition with iron on transferrin (Chitam-
bar, 2004a,b; Jakupec and Keppler, 2004a,b) and inhibits
ribonucleotide reductase (Chitambar, 2004a). Gallium
has also been found to initiate apoptosis by activation
of the caspase system (Chitambar, 2004c). Gallium
has also been found to exert an attenuating effect on
hypercalcemia related to a variety of cancers (Leyland-
Jones, 2004). This may occur in part by a mechanism
involving inhibition of tyrosine phosphatase (Berggren
et al ., 1993). In addition, synthesis of gallium metallopor-
phyrins (Begum et al ., 2003) and complexes with amin
phenol ligands (Harpstrite, et al ., 2003) have been tested
as antimalarial agents against Plasmodium falciparum .
In addition, GaAs lasers operated at 904 nm have
been used in myofacial pain syndrome (Gur et al ., 2004)

and bone formation (Khadra et al ., 2004a,b). Gallium
alloys have also been used for dental implants (Claire
and Williams, 2001; Garhammer et al ., 2004; Hero et al .,
1997).

4 ENVIRONMENTAL LEVELS
AND EXPOSURES

There are limited published data on environmental
exposure levels to gallium.

4.1 Food and Daily Intake
Although arsenic intake from food has been
reported (see Chapter 19), no data on food intake
specifi cally for Ga or GaAs could be found despite
investigations showing the dissociation of the gallium
and arsenic moieties (see Section 5.1.1). Relevant to
issues regarding gallium from food are the reports of
children's Ga intake from breastfeeding because of
the presence of Ga in human milk (Wappelhorst et al .,
2002).

4.2 Water, Sediments, Soil, and Ambient Air
Orians (1993) reported open seawater concentra-
tions of gallium in the range of 2-60 picomolar after
preconcentration and ICP-MS analysis. Anand et al .
(2003) reported Ga concentrations over a range of