パラジウム

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

1.5 [mg/m3]

160 [mg/m3]

970 [mg/m3]

IDENTIFICATION: Palladium is a steel white ductile metallic element. It is stable in air and resistant to attack by most reagents. It is soluble in a mixture of hydrochloric and nitric acids. Palladium and its alloys are used as catalysts in the petrochemical and automotive industries. Used in electronics and in dental applications. Purified metals between 99.9% and 99.99% are available for chemical use as foil, granules, rod or wire. HUMAN EXPOSURE: The general population is primarily exposed to palladium through dental alloys, jewlery, food and emissions from automobile catalytic converters. There are limited data concerning the distribution of palladium from dental resorations in human tissues or fluids. Populations at special risk of palladium allergy include people with known nickel allergy. ANIMAL STUDIES: Six months after a single intratracheal application of palladium dust, several histopathological signs of inflammation were noted in the lungs of rats. Daily oral administration of palladium dust over 6 months resulted in changes in several blood and urine parameters. Palladium applied in its metallic form showed no or little cytotoxicity.[

Palladium ions are able to inhibit most major cellular fuctions. They form strong complexes with both inorganic and organic ligands, substitute essential ions, bind to amino acids and various enzymes including creatine kinase and prolyl hydroxylase, and interact with functional groups of other macromolecules such as DNA leading to strand breakage. (L798)

Palladium (Pd) is found with platinum, gold, and nickel ores.

Palladium belongs to the platinum group metals (ruthenium, osmium, rhodium, iridium, palladium and platinum), which are rare elements often found together in nature(1). In the lithosphere, the estimated concentration of platinum group metals range from 0.05 to 0.5 ppm(2). Palladium's abundance in the earth's crust is 0.001-0.01 ppm(3).

/CASE REPORTS/ A 54-yr-old woman patient had symptoms of stomatitis and asthma following the provision of a dental prosthesis in July 1991. ...A positive patch test reaction /was found/ to palladium only, without any concomitant metallic contact dermatitis; in particular there was no sensitization to nickel. This is a very rare sensitization. After replacement of the dental alloy the clinical symptoms improved.

/CASE REPORTS/ Granulomatous tissue reactions due to jewelry made of gold, silver, nickel and palladium are rare but nevertheless have been known for a long time. A female patient developed nodular infiltrates after having been pierced with ear stickers containing palladium. A contact allergic reaction could be demonstrated as the underlying cause by inducing similar histological changes following patch testing with palladium.

/CASE REPORTS/ A patient with a metal dental bridge complained of itching and pain in the oral cavity. She suffered also from recurrent blisters, ulceration, and infection of the oral mucous membrane. Skin tests carried out ... on this patient showed... a positive allergic reaction to... palladium metal.

/CASE REPORTS/ ...A case of linear lichen planus extending from the right cheek to the jaw, which was accompanied by itching and an unusual sensation in the mouth /is described/. The eruption was located along the mandible and aligned with the mandibular nerve. The right molars of the patient contained metal compounds and these were considered to be the cause of his disease. Patch testing with various dental metals showed positive reactions to palladium and platinum. A biopsy specimen showed a lichenoid reaction in the lesional tissue, and dermal contact dermatitis was noted at the palladium patch test site. His dentist reported that palladium-silver-gold or nickel-chrome alloys without platinum had been used in the crown and bridge of his molars. After removal of the dental alloys, the skin eruption resolved with some residual hyperpigmentation. In addition, the peculiar mouth sensation disappeared dramatically within 2 months.

For more Human Toxicity Excerpts (Complete) data for PALLADIUM, ELEMENTAL (11 total), please visit the HSDB record page.

/LABORATORY ANIMALS: Acute Exposure/ Palladium powder /was given to/ rats by enteral (intragastric) /administration/ dose not specified. Clinical signs and toxic effects /include/: necrobiotic changes in the mucous membranes of the gastrointestinal tract, granular dystrophy of hepatocytes, swelling in the epithelium of kidney tubules. /from table/

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ 6 months after a single intratracheal application of 50 mg palladium dust (about 143 mg/kg bw), the lungs of rats (Sprague-Dawley, female, n=10) were histopathologically examined. There were several signs of inflammatory responses (peribronchial inflammation, lymphocyte infiltration, interstitial pneumonia, formation of granulomata) observed, but no indications of interstitial fibrosis... .

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ Acute toxicity tests with 6 different palladium-containing dental alloys (pulverized; mean particle size 200 um; palladium content: 9-80 mass %) have been performed with rats (Wistar, n=10; 5 females, 5 males). Oral doses of 200 mg/kg bw (in gelatin capsules) did not cause deaths or apparent toxic signs. Histopathological changes in lung, liver and kidney of rats (Sprague-Dawley; n=14) were seen 5 weeks after single oral administration of cut dental alloy material (1 g/kg bw, in gelatin capsules; 6 different alloys; particle size not specified), which contained palladium at 2.5-4 weight % and total noble metals (gold, palladium) at 44-62%. However, alloys of a higher noble metal (gold, palladium, platinum) content (78-97%) containing palladium at 4-26.5% did not elicit significant effects.

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ Six different pulverized palladium-containing dental alloys have been tested for their subacute toxicity in rats (Wistar, n=10, 5 females, 5 males). Compared with controls, all specimens caused significant histopathological changes in lung, liver, kidney, small intestine and colon following daily oral doses of 1000 mg/kg bw for 7 days (and sacrifice after 7 additional days). The strongest effects were seen with compositions containing copper and/or indium: Pd73, Cu14, In5; Pd74, Sn16, Cu9; and Au51, Pd39, In4-9. The weakest effects were observed for the Pd58, Ag30, Sn6 alloy, and the changes due to the Pd80, Sn7, Ga6-8 and Au77, Pt10, Pd9 alloys fell in between. Some histocompatibility tests have been performed with several implants of palladium-containing dental alloys of different compositions. Four to 12 weeks after sc implantation of the experimental alloys into guinea-pigs, mice, or rats, or after intramuscular implantation into rabbits, the tissue reactions at the implantation site varied from slight to severe. The most extreme reactions were recorded when copper and/or indium were present as additional components. Altogether, the contribution of palladium to adverse effects of dental mixtures is not clear.

For more Non-Human Toxicity Excerpts (Complete) data for PALLADIUM, ELEMENTAL (9 total), please visit the HSDB record page.

Palladium concentrations in personal samples collected in 1996 during industrial operations involving the handling of palladium compounds were reported to be between 0.4 and 11.6 ug Pd/cu m as a 8-hour time-weighted average(1). Mean palladium concentrations of 3.5 ug/cu m, with local exhaust ventilation, and 5.5 ug/cu m, without dust control, were measured in the breathing zone of dental technicians(1). Palladium concentrations in air in a platinum and palladium refinery in New Jersey ranged from 0.001 to 0.36 ug/cu m(1).

Dust samples were collected in 1985 from the surfaces of plants along side roads in San Diego, CA; palladium concentrations ranged from 0.015 mg/kg dry weight in dust collected along Bellaire Court, a residential street with light traffic, up to 0.28 mg/kg dry weight in dust collected approximately 2 ft from the edge of Interstate 5, a major freeway(1). Palladium concentrations of 0.001-0.146 mg/kg were reported in urban road dusts in Germany in 1995(2).

There are no established detoxification methods following poisoning by palladium or its compounds. Because of its poor absorption by the body, removal from exposure is the best remedy, when palladium is cleared by natural processes.

Basic treatment: Establish a patent airway. Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if needed. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with normal saline during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 ml/kg up to 200 ml of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool ... . Cover skin burns with dry sterile dressings after decontamination ... . /Poison A and B/

Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in respiratory arrest. Positive pressure ventilation techniques with a bag valve mask device may be beneficial. Monitor cardiac rhythm and treat arrhythmias as necessary ... . Start an IV with D5W /SRP: "To keep open", minimal flow rate/. Use lactated Ringer's if signs of hypovolemia are present. Watch for signs of fluid overload. Consider drug therapy for pulmonary edema ... . For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Treat seizures with diazepam (Valium) ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Poison A and B/

Noble metal alloy: (a) Identification. A noble metal alloy is a device composed primarily of noble metals, such as gold, palladium, platinum, or silver, that is intended for use in the fabrication of cast or porcelain-fused-to-metal crown and bridge restorations. (b) Classification. Class II (special controls). The special control for these devices is FDA's "Class II Special Controls Guidance Document: Dental Noble Metal Alloys." The devices are exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in §872.9. See §872.1(e) for availability of guidance information. /Noble metal alloy/