Chemistry Reference
In-Depth Information
CHAPTER
37
Platinum
*
MIRJA KIILUNEN AND ANTERO AITIO
ABSTRACT
with susceptibility to platinum sensitization. Smokers
have a higher risk for platinum sensitization.
No health effects from environmental exposure to
platinum have been reported.
With the exception of platinum-containing chemo-
therapeutic drugs such as cisplatin (
cis
-diamminedichlo-
roplatinum), no relevant human or experimental data
are available on the potential carcinogenicity or tera-
togenicity of platinum compounds. Cisplatin and oth-
er platinum-containing chemotherapeutic drugs are
genotoxic in a variety of test systems, and even other
platinum compounds have induced mutations
in vitro
(but not
in vivo
).
Platinum compounds used as anticancer drugs such as
cisplatin and its analogs are not covered in detail in this
chapter; they are discussed only when it is informative
from the point of view of structure-activity relationships.
Commercial sources of platinum are sulfi de and ar-
senide minerals, and increasingly, recycled platinum.
The main source of platinum in the environment is
release from vehicle catalysts, and platinum concen-
trations near highways and urban areas have gradually
increased. In occupational exposure, the form of
platinum is mainly coordination complexes, most of-
ten with chlorine as a ligand, whereas the platinum
released from automotive catalysts is metallic or
oxidic.
The acute toxicity of platinum compounds depends
mainly on their solubility, soluble platinum salts being
more toxic than the compounds with lower solubility,
such as oxides. Chloroplatinates are irritating to the
eye and skin.
The main health effect of platinum compounds is
sensitization; the symptoms of platinum salt sensitiv-
ity include irritation of the eyes and upper respira-
tory tract and asthma. Allergenic potency of platinum
compounds seems to be limited to coordination com-
plexes containing halogen ligands as leaving groups,
hexa- and tetrachloroplatinates being the most potent
sensitizers. Neutral coordination complexes such as di-
amminedichloroplatinum do not seem to be allergenic.
Bromine and iodine analogs of platinates may cause
sensitization but seem to be less potent. The mecha-
nism of platinum salt allergy is likely to be type 1 (i.e.,
involves IgE). Atopic constitution is not associated
1
PHYSICAL AND CHEMICAL PROPERTIES
Platinum (Pt), CAS 7440-65-7: atomic mass, 195.078;
atomic number, 78; density, 21.447 (calculated); melt-
ing point, 1773.5 ± 1°C; boiling point, approximately
3827°C; silver-grey, lustrous, malleable, and ductile
metal, face-centered cubic; oxidation states chiefl y
+2, +4, also +1, +5, +6. Platinum is also prepared in
the form of a black powder (platinum black) and
spongy masses (platinum sponge). Six isotopes
occur naturally, 190 (0.01%), 192 (0.8%), 194 (32.9%),
195 (33.8%), 196 (25.2%), and 198 (7.2%) The isotope
190 is radioactive with t
½
6.9*10
11
years. Artifi cial
radioactive isotopes include 173-189, 191, 193, 197,
199-201.
*
The views presented in this chapter are those of the authors and
do not necessarily refl ect the decisions or stated policies of the affi li-
ated organizations
