CAS No. 7440-06-4
Platinum is a silver-gray, lustrous metal found naturally in extremely low amounts in the earth's crust and is typically associated with sulfide-ore bodies of nickel, copper, and iron. Important properties of platinum are resistance to corrosion, strength at high temperatures, and high catalytic activity. Platinum compounds are used in electrodes, jewelry, dental alloys, thick-film circuits printed on ceramic substrates, as oxidation catalysts in chemical manufacturing, and as drugs (e.g., cisplatin, carboplatin) in the treatment of cancer. Platinum-rhodium and platinum-palladium crystals are used as catalysts in petroleum refining and in vehicular catalytic converters to control exhaust emissions. Platinum-rhodium compounds are also used in glass and glass-fiber manufacture and in high-temperature thermocouples. Higher environmental soil concentrations of platinum from vehicular emissions have been found near roadways (Farago et al., 1998); however, the ambient air concentrations of platinum associated with its use in automotive engine catalytic converters are estimated to be thousands of times lower than occupational exposure limits.
Human health effects from platinum at low environmental doses or at biomonitored levels from low environmental exposures are unknown. Toxicity is determined by the type of compound (e.g., metallic, inorganic salt, or organometallic), route of exposure (e.g., intravenous medicinal use, inhalational, cutaneous, oral), and duration of exposure. Platinum metal is biologically inert, whereas soluble platinum compounds (e.g., halogenated salts) encountered in occupational settings can cause platinum salt hypersensitivity with symptoms that include bronchitis and asthma after inhalational exposure and contact dermatitis after skin exposure. Animals exposed to cholorplatinate salts used in industry have demonstrated severe hypersensitivity with asthma-like symptoms and anaphylactic shock (Parrot et al., 1969; Saindell et al., 1969). Platinum metal and insoluble salts can produce eye irritation. When ingested or inhaled, platinum metal and insoluble salts are very poorly absorbed (<1% of a dose) and cleared from the body within a week after a single dose. Most absorbed platinum accumulates in the kidneys and is excreted in urine (Moore et al., 1975a, 1975b). The pharmaceutical cisplatin is an animal carcinogen and reasonably anticipated to be a human carcinogen as determined by NTP. The carcinogenicity of other platinum compounds remains uncertain. Workplace air standards for external exposure are established for soluble salts of platinum by OSHA and ACGIH, or recommended for the metal form by NIOSH (Czerczak and Gromiec, 2000). Information about external exposure (i.e., environmental levels) and health effects is available from the International Programme on Chemical Safety at http://www.inchem.org/documents/ehc/ehc/ehc125.htm.
Urinary platinum levels reflect recent exposure. Levels of platinum in urine for the U.S. population were below the limits of detection, which have ranged from 0.009-0.07 µg/L in the National Report on Human Exposure to Environmental Chemicals (CDC, 2012). Several studies have shown that background concentrations in general populations were usually less than 0.005 µg/L (Iavicoli et al., 2004; Wilhelm et al., 2004) or less than 0.01 µg/L (Becker et al., 2003; Herr et al., 2003; Schierl et al., 1998).
One study found that traffic-control officers had no greater urinary platinum concentrations than office-based control subjects (Iavicoli et al., 2004). Gold-platinum dental restorations were correlated with increased urinary platinum concentrations, which elevate urinary platinum by five to twelve-fold (Begerow et al., 1999; Herr et al., 2003; Schierl, 2001). Platinum-industry and precious-metal workers had urinary concentrations about one-thousand times higher than general populations (Schierl et al., 1998). Modest (ten-fold or less) elevations in urinary platinum concentrations were associated with handling of cisplatin and carboplatin by pharmacy and other hospital personnel (Ensslin et al., 1997; Pethran et al., 2003).
Finding a measurable amount of platinum in the urine does not imply that the level of platinum causes an adverse health effect. Biomonitoring studies on levels of platinum provide physicians and public health officials with reference values so that they can determine whether people have been exposed to higher levels of platinum than are found in the general population. Biomonitoring data can also help scientists plan and conduct research on exposure and health effects.
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