Indium - Toxicology of Metals - page 559

5.4 Biological Half-Time
The biological half-time for indium depends some-
what on the chemical form administered, and excre-
tion seems to follow a biphasic pattern. Mice given
intravenous injections of 11 4 indium chloride showed a
biological half-time of 1.9 days for the fast-phase com-
ponent representing approximately 50% of the body
burden, and 69 days for the slow phase. Hydrated
11 4 indium oxide had a biological half-time of 2 days
for the fast-phase component representing approxi-
mately 25% of the body burden, and 73.8 days for the
slow phase after intravenous injection (Castronovo,
1970; Castronovo and Wagner, 1971; 1973). Stern et al .
(1967) found a biological half-time of 3.5 days for
clearance of hydrated indium oxide from the lungs of
mice after intravenous administration. A whole-body
biological half-time of 14-15 days was reported by
these authors.
Smith et al . (1960) reported that approximately
60% of an intratracheal injection of radioactive
indium left the lungs of rats within 16 days. Excre-
tion of indium from the bodies of these animals was
also biphasic. The biological half-time for inhaled
indium sesquioxide particles has been found to be
approximately 8-10 days in rat lungs (Morrow et al .,
1958). Isitman et al . (1974) reported the biphasic half-
times for 111 InCl 3 in lungs of adult human subjects
exposed to an aerosol to be 16 and 35 minutes, respec-
tively. Yamauchi et al . (1992) reported the results of
intratracheal instillation studies of InAs particles in
hamsters and observed the greatest rate of excretion
(0.07%/day) during the fi rst 5 days after treatment
for the In component.

7.1 Local Effects and Dose-Response
Relationships

7.1.1 Animals

Podosinovskij (1965) administered 50 mg of In 2 O 3
intratracheally to rats and found pneumonic and ini-
tial fi brotic changes in the lungs. The pulmonary toxic-
ity of indium diselenide was reported by Morgan et al .
(1995), who observed increased pulmonary infl amma-
tion in lungs of female rats 72 hours after intratracheal
instillation of this compound. Similar infl ammatory
changes associated with markers of oxidative stress
and the development of lung carcinogenesis were
observed in rats exposed to an aerosol of InP for 105
weeks (Gottschling et al ., 2001). Tanaka (2003) reported
that InAs was more toxic to the lung of experimen-
tal animals than GaAs or AlGaAs after intratracheal
instillation.

7.1.2 Humans

Raiciulescu et al . (1972) reported that 3 patients of
a total of 770 persons injected with colloidal 11 3 indium
for liver scanning developed severe vascular shock
within 20 minutes after treatment. Shock was found
to last from 10 minutes to 1 hour. Increased blood
and urinary concentrations of indium have been
reported among optoelectronics industry workers in
Taiwan (Liao et al ., 2004), and pulmonary fi brosis has
been reported in a person exposed to inhaled indium-
tin oxide for 4 years in a fl at-panel display facility in
Japan (Homma et al ., 2005).

7.2 Systemic Effects and Dose-Response
Relationships

6 LEVELS IN TISSUES AND
BIOLOGICAL FLUIDS

7.2.1 Animals

The primary adverse effects of ionic indium are
exerted in the kidneys, whereas colloidal hydrated
indium oxide damages the reticuloendothelial sys-
tem. A single intravenous injection of indium chloride
has been reported to cause extensive necrosis of the
renal proximal tubules both in rats (3.6 mg/kg) and
mice (16.5 mg/kg) (Castronovo, 1970; Castronovo
and Wagner, 1971; Downs et al ., 1959). Administra-
tion of colloidal hydrated indium oxide by this route
produced necrosis of cells in the liver and spleen
(Castronovo, 1970; Castronovo and Wagner, 1971;
Downs et al ., 1959; Stern et al ., 1967). Lung damage has
also been reported in mice given subcutaneous injec-
tions of In(SO4) 3 (Yoshikawa and Hasegawa, 1971).
Lower hemoglobin and neutrophil counts have been
observed in rats, mice, and rabbits injected with ionic
indium (Downs et al ., 1959; McCord et al ., 1942; Steidle,

Smith et al . (1978) have extensively reviewed the
literature concerning reported tissue concentrations
of indium in animal and human tissues, and most val-
ues have been found to be <0.05 ppm. Tissues of fi sh
and shellfi sh collected near a smelter outfall, how-
ever, have been found to range up to 10-15 mg/kg
(wet weight).

7 EFFECTS AND DOSE-RESPONSE
RELATIONSHIPS

Indium is considered to be a nonessential element.
At present, there are no published data on the toxicity
of organoindium compounds or on indium-containing
nanoparticles.