Platinum Group Elements in the Environment: Emissions and Exposure - Reviews of Environmental Contamination and Toxicology - page 117

The first studies on Pt release from catalytic converters demonstrated that
Pt 4+ -containing oxide is produced from the reaction between metallic Pt and oxy-
gen, or air, at 500 C. Until recently, it was concluded that the majority of Pt released
from catalytic converters is in metallic form, and only a small percentage is oxi-
dized, probably to the Pt 4+ form (Artelt et al. 2000). The latest investigations have
demonstrated that the soluble fraction of PGEs, emitted from automobile catalyst,
may be higher than formerly thought (about 0-30% of the total PGEs released)
(Moldovan et al. 2002). Palacios et al. (2000b) demonstrated that the soluble frac-
tion of emitted PGEs constitutes 10% of the total, and exists mainly in the oxidized
state and in chloride forms. It has also been proven that aluminum oxide and silica
act as carriers for Pd released from catalytic converters, and that this metal probably
occurs in halogenated form (Ravindra et al. 2004). Moreover, research on the water
solubility of emitted Pt compounds, in samples collected from roads, undermines
the hypothesis that PGEs are emitted from catalytic converters mainly in metallic
form (Jarvis et al. 2001). Fig. 2 presents the content of different forms of Pt, Pd,
and Rh that exist in exhaust fumes, and also presents the effect of engine age on
emissions. Investigations concerning the determination of chemically active Pt in
road tunnel dust have indicated that Pt is predominantly emitted from the converter
in biologically available form (up to about 40%) (Fliegel et al. 2004).

4.2 Emission of PGEs via Hospital Wastewater

In recent yr, there has been a broad and increasing use of Pt complexes as antican-
cer drugs. Cisplatinum, oxaliplatinum, and carboplatinum are successfully used to
treat selected malignant tumors. The above-mentioned anticancer drugs have been
consecutively introduced since 1978. Research, including medical trials, is cur-
rently in progress on a new generation of Pt anticancer drugs (Esteban-Fernandez
et al. 2007).
The biological half-life of the Pt anticancer drugs ranges from 160 to 720 d
(Lenz et al. 2005). It has been estimated that Pt concentration in the urine of
patients receiving chemotherapy is 40 times higher than normal physiological
levels, even 8 yr after treatment ends (Schierl et al. 1995). The main accumula-
tion sites for Pt in humans are kidneys, liver, spleen, and adrenal glands (Uozumi
et al. 1993).
Approximately 70% of the total Pt dose received by a patient is excreted in
urine. This amount includes 24-32% of cisplatin, 72-82% of carboplatinum, and
28-44% of oxaliplatin eliminated from the body, within 24 hr of treatment
(Pyrzyñska 2000; Lenz et al. 2005). Pt excreted in urine reaches the sewerage
system (Kümmerer and Helmers 1997), making hospitals an environmental
emission source of this element. However, data from numerous studies indicate that
hospitals play a secondary role in PGE emissions in comparison to other anthropo-
genic sources, particularly motor VECs (Kümmerer et al. 1999). The above data
have been confirmed by investigations of Pt concentrations in municipal sewage;