Palladium 12 (Now Closed) - Movie Theater in Downtown BirminghamPalladium | Outdoor Equipped
Free Shipping. Always.
Sorry, there are no products in this collection28,476被浏览2,425,578分享邀请回答14K619 条评论分享收藏感谢收起2.1K127 条评论分享收藏感谢收起Palladium (EHC 226, 2002)
Environmental Health Criteria 226
This report contains the collective views of an international group of experts and does not necessarily represent the decisions or the stated policy of the United Nations Environment Programme, the International Labour Organization or the World Health Organization.
First draft prepared by Dr Christine Melber, Dr Detlef Keller and Dr Inge Mangelsdorf, Fraunhofer Institute for Toxicology and Aerosol Research, Hanover, Germany
Published under the joint sponsorship of the United Nations Environment Programme, the International Labour Organization and the World Health Organization, and produced within the framework of the Inter-Organization Programme for the Sound Management of Chemicals.
World Health Organization&&&&&&&Geneva, 2002
The International Programme on Chemical Safety (IPCS), established in 1980, is a joint venture of the United Nations Environment Programme (UNEP), the International Labour Organization (ILO) and the World Health Organization (WHO). The overall objectives of the IPCS are to establish the scientific basis for assessment of the risk to human health and the environment from exposure to chemicals, through international peer review processes, as a prerequisite for the promotion of chemical safety, and to provide technical assistance in strengthening national capacities for the sound management of chemicals.
The Inter-Organization Programme for the Sound Management of Chemicals (IOMC) was established in 1995 by UNEP, ILO, the Food and Agriculture Organization of the United Nations, WHO, the United Nations Industrial Development Organization, the United Nations Institute for Training and Research and the Organisation for Economic Co-operation and Development (Participating Organizations), following recommendations made by the 1992 UN Conference on Environment and Development to strengthen cooperation and increase coordination in the field of chemical safety. The purpose of the IOMC is to promote coordination of the policies and activities pursued by the Participating Organizations, jointly or separately, to achieve the sound management of chemicals in relation to human health and the environment.
WHO Library Cataloguing-in-Publication Data
Palladium.
(Environmen 226)
1. Palladium - toxicity 2.Palladium - adverse effects 3.Environmental exposure
4.Occupational exposure 5.Risk assessment I.International Programme for
Chemical Safety II.Series
ISBN&92 4 &&&&&&&&&&(NLM classification: QV 290)
The World Health Organization welcomes requests for permission to reproduce or translate its publications, in part or in full. Applications and enquiries should be addressed to the Office of Publications, World Health Organization, Geneva, Switzerland, which will be glad to provide the latest information on any changes made to the text, plans for new editions, and reprints and translations already available.
&World Health Organization 2002
Publications of the World Health Organization enjoy copyright protection in accordance with the provisions of Protocol&2 of the Universal Copyright Convention. All rights reserved.
The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recommended by the World Health Organization in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters.
The Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, Germany, provided financial support for, and undertook the printing of, this publication.
ENVIRONMENTAL HEALTH CRITERIA FOR PALLADIUM
NOTE TO READERS OF THE CRITERIA MONOGRAPHS
Every effort has been made to present information in the criteria monographs as accurately as possible without unduly delaying their publication. In the interest of all users of the Environmental Health Criteria monographs, readers are requested to communicate any errors that may have occurred to the Director of the International Programme on Chemical Safety, World Health Organization, Geneva, Switzerland, in order that they may be included in corrigenda.
A detailed data profile and a legal file can be obtained from the International Register of Potentially Toxic Chemicals, Case postale 356, 1219 Ch&telaine, Geneva, Switzerland (telephone no. + 41 22 – 9799111, fax no. + 41 22 – 7973460, E-mail irptc@unep.ch).
This publication was made possible by grant number 5 U01 ES02617-15 from the National Institute of Environmental Health Sciences, National Institutes of Health, USA, and by financial support from the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, Germany.
Environmental Health Criteria
Objectives
In 1973, the WHO Environmental Health Criteria Programme was initiated with the following objectives:
to assess information on the relationship between exposure to environmental pollutants and human health, and to provide guidelines for set
to identify new or
to identify gaps in knowledge concerning the health e
to promote the harmonization of toxicological and epidemiological methods in order to have internationally comparable results.
The first Environmental Health Criteria (EHC) monograph, on mercury, was published in 1976, and since that time an ever-increasing number of assessments of chemicals and of physical effects have been produced. In addition, many EHC monographs have been devoted to evaluating toxicological methodology, e.g., for genetic, neurotoxic, teratogenic and nephrotoxic effects. Other publications have been concerned with epidemiological guidelines, evaluation of short-term tests for carcinogens, biomarkers, effects on the elderly and so forth.
Since its inauguration, the EHC Programme has widened its scope, and the importance of environmental effects, in addition to health effects, has been increasingly emphasized in the total evaluation of chemicals.
The original impetus for the Programme came from World Health Assembly resolutions and the recommendations of the 1972 UN Conference on the Human Environment. Subsequently, the work became an integral part of the International Programme on Chemical
Safety (IPCS), a cooperative programme of UNEP, ILO and WHO. In this manner, with the strong support of the new partners, the importance of occupational health and environmental effects was fully recognized. The EHC monographs have become widely established, used and recognized throughout the world.
The recommendations of the 1992 UN Conference on Environment and Development and the subsequent establishment of the Intergovernmental Forum on Chemical Safety with the priorities for action in the six programme areas of Chapter 19, Agenda 21, all lend further weight to the need for EHC assessments of the risks of chemicals.
The criteria monographs are intended to provide critical reviews on the effects on human health and the environment of chemicals and of combinations of chemicals and physical and biological agents. As such, they include and review studies that are of direct relevance for the evaluation. However, they do not describe every study carried out. Worldwide data are used and are quoted from original studies, not from abstracts or reviews. Both published and unpublished reports are considered, and it is incumbent on the authors to assess all the articles cited in the references. Preference is always given to published data. Unpublished data are used only when relevant published data are absent or when they are pivotal to the risk assessment. A detailed policy statement is available that describes the procedures used for unpublished proprietary data so that this information can be used in the evaluation without compromising its confidential nature (WHO (1999) Revised Guidelines for the Preparation of Environmental Health Criteria Monographs. PCS/99.9, Geneva, World Health Organization).
In the evaluation of human health risks, sound human data, whenever available, are preferred to animal data. Animal and in vitro studies provide support and are used mainly to supply evidence missing from human studies. It is mandatory that research on human subjects is conducted in full accord with ethical principles, including the provisions of the Helsinki Declaration.
The EHC monographs are intended to assist national and international authorities in making risk assessments and subsequent risk management decisions. They represent a thorough evaluation of risks and are not, in any sense, recommendations for regulation or standard setting. These latter are the exclusive purview of national and regional governments.
The layout of EHC monographs for chemicals is outlined below.
Summary — a review of the salient facts and the risk evaluation of the chemical
Identity — physical and chemical properties, analytical methods
Sources of exposure
Environmental transport, distribution and transformation
Environmental levels and human exposure
Kinetics and metabolism in laboratory animals and humans
Effects on laboratory mammals and in vitro test systems
Effects on humans
Effects on other organisms in the laboratory and field
Evaluation of human health risks and effects on the environment
Conclusions and recommendations for protection of human health and the environment
Further research
Previous evaluations by international bodies, e.g., IARC, JECFA, JMPR
Selection of chemicals
Since the inception of the EHC Programme, the IPCS has organized meetings of scientists to establish lists of priority chemicals for subsequent evaluation. Such meetings have been held in Ispra, Italy, 1980; Oxford, United Kingdom, 1984; Berlin, Germany, 1987; and North Carolina, USA, 1995. The selection of chemicals has been based on the following criteria: the existence of scientific evidence that the substance presents a hazard to human health and/ the possible use, persistence, accumulation or degradation of the substance shows that there may be significant human or en the size and nature of populations at risk (both human and other species) and risks international concern, i.e., the substance is of major interest
adequate data on the hazards are available.
If an EHC monograph is proposed for a chemical not on the priority list, the IPCS Secretariat consults with the cooperating organizations and all the Participating Institutions before embarking on the preparation of the monograph.
Procedures
The order of procedures that result in the publication of an EHC monograph is shown in the flow chart on the next page. A designated staff member of IPCS, responsible for the scientific quality of the document, serves as Responsible Officer (RO). The IPCS Editor is responsible for layout and language. The first draft, prepared by consultants or, more usually, staff from an IPCS Participating Institution, is based initially on data provided from the International Register of Potentially Toxic Chemicals and from reference databases such as Medline and Toxline.
The draft document, when received by the RO, may require an initial review by a small panel of experts to determine its scientific quality and objectivity. Once the RO finds the document acceptable as a first draft, it is distributed, in its unedited form, to well over 150 EHC contact points throughout the world who are asked to comment on its completeness and accuracy and, where necessary, provide additional material. The contact points, usually designated by governments, may be Participating Institutions, IPCS Focal Points or individual scientists known for their particular expertise. Generally, some four months are allowed before the comments are considered by the RO and author(s). A second draft incorporating comments received and approved by the Director, IPCS, is then distributed to Task Group members, who carry out the peer review, at least six weeks before their meeting.
The Task Group members serve as individual scientists, not as representatives of any organization, government or industry. Their function is to evaluate the accuracy, significance and relevance of the information in the document and to assess the health and environmental risks from exposure to the chemical. A summary and recommendations for further research and improved safety aspects are also required. The composition of the Task Group is dictated by the range of expertise required for the subject of the meeting and by the need for a balanced geographical distribution.
The three cooperating organizations of the IPCS recognize the important role played by nongovernmental organizations. Representatives from relevant national and international associations may be invited to join the Task Group as observers. While observers may provide a valuable contribution to the process, they can speak only at the invitation of the Chairperson. Observers do not participate in the final evalua this is the sole responsibility of the Task Group members. When the Task Group considers it to be appropriate, it may meet in camera.
All individuals who as authors, consultants or advisers participate in the preparation of the EHC monograph must, in addition to serving in their personal capacity as scientists, inform the RO if at any time a conflict of interest, whether actual or potential, could be perceived in their work. They are required to sign a conflict of interest statement. Such a procedure ensures the transparency and probity of the process.
When the Task Group has completed its review and the RO is satisfied as to the scientific correctness and completeness of the document, the document then goes for language editing, reference checking and preparation of camera-ready copy. After approval by the Director, IPCS, the monograph is submitted to the WHO Office of Publications for printing. At this time, a copy of the final draft is sent to the Chairperson and Rapporteur of the Task Group to check for any errors.
It is accepted that the following criteria should initiate the updating of an EHC monograph: new data are available that would substantially c there is public concern for health or environmental effects of the agent because an appreciable time period has elapsed since the last evaluation.
All Participating Institutions are informed, through the EHC progress report, of the authors and institutions proposed for the drafting of the documents. A comprehensive file of all comments received on drafts of each EHC monograph is maintained and is available on request. The Chairpersons of Task Groups are briefed before each meeting on their role and responsibility in ensuring that these rules are followed.
WHO TASK GROUP ON ENVIRONMENTAL HEALTH CRITERIA FOR PALLADIUM
Professor Werner Aberer, Department of Dermatology, University of Graz, Graz, Austria
Dr Janet Kielhorn, Fraunhofer Institute for Toxicology and Aerosol Research, Hanover, Germany (Co-Rapporteur)
Assistant Professor Patrick Koch, Department of Dermatology, Saarland University Hospital, Homburg/Saar, Germany
Dr Jorma Maki-Paakkanen, Department of Environmental Medicine, National Public Health Institute, Kuopio, Finland
Mr Heath Malcolm, Centre for Ecology and Hydrology, Monks Wood, Abbots Ripton, Huntingdon, United Kingdom (Co-Rapporteur)
Professor Gunnar Nordberg, Unit of Environmental Medicine, Department of Public Health and Clinical Medicine, Umea University, Umea, Sweden (Chairman)
Professor John C. Wataha, Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, Georgia, USA
Dr Mark White, Health and Safety Laboratory, Sheffield, United Kingdom
Secretariat
Mr Yoshikazu Hayashi, International Programme on Chemical Safety, World Health Organization, Geneva, Switzerland
Dr Detlef Keller, Fraunhofer Institute for Toxicology and Aerosol Research, Hanover, Germany
Dr Inge Mangelsdorf, Fraunhofer Institute for Toxicology and Aerosol Research, Hanover, Germany
Dr Christine Melber, Fraunhofer Institute for Toxicology and Aerosol Research, Hanover, Germany
Professor Fedor Vali? , WHO/IPCS Scientific Adviser, Department of Environmental and Occupational Health, Andrija ?tampar School of Public Health, University of Zagreb, Zagreb, Croatia (Responsible Officer)
Dr Peter Linnett, Johnson Matthey plc, Royston, United Kingdom
ENVIRONMENTAL HEALTH CRITERIA FOR PALLADIUM
A Task Group on Environmental Health Criteria for Palladium met at the Fraunhofer Institute for Toxicology and Aerosol Research, Hanover, Germany, from 8 to 12 May 2000. Professor H. Muhle, Deputy Director, Fraunhofer Institute for Toxicology and Aerosol Research, opened the meeting and welcomed the participants on behalf of the host institution. Professor F. Vali? welcomed the participants on behalf of the Director, IPCS, and the heads of the three cooperating organizations of the IPCS (UNEP/ILO/WHO). The Task Group reviewed and revised the draft of the monograph, made an evaluation of the risks for human health and the environment from exposure to palladium and made recommendations for health protection and further research.
The first draft was prepared by Dr Christine Melber, Dr Detlef Keller and Dr Inge Mangelsdorf, Fraunhofer Institute for Toxicology and Aerosol Research, Hanover, Germany. The second draft was also prepared by the same authors, incorporating comments received following the circulation of the first draft to the IPCS Contact Points for Environmental Health Criteria monographs.
Professor F. Vali? was responsible for the overall scientific content of the monograph, and Dr P.G. Jenkins, IPCS Central Unit, was responsible for coordinating the technical editing of the monograph.
The efforts of all who helped in the preparation and finalization of the monograph are gratefully acknowledged.
ACRONYMS AND ABBREVIATIONS
atomic absorption spectrometry
adenosine triphosphatase
curie (1 Ci = 3.7 × 1010 Bq)
deoxyribonucleic acid
median effective concentration
Environmental Health Criteria monograph
Food and Agriculture Organization of the United Nations
forced expiratory volume in 1 s
graphite furnace atomic absorption spectrometry
International Agency for Research on Cancer
median inhibitory concentration
inductively coupled plasma
inductively coupled plasma atomic emission spectrometry
inductively coupled plasma mass spectrometry
International Labour Organization
International Programme on Chemical Safety
Joint FAO/WHO Expert Meeting on Food Additives
Joint FAO/WHO Meeting on Pesticide Residues
inhibition constant
median lethal concentration
median lethal dose
memory lymphocyte immunostimulation assay
mass median aerodynamic diameter
mass spectrometry
3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide
National Bureau of Standards (USA)
no-observed-adverse-effect level
no-observed-effect concentration
no-observed-effect level
Organisation for Economic Co-operation and Development
platinum group metal
particulate matter with aerodynamic diameter &2.5 um
particulate matter with aerodynamic diameter &10 um
ribonucleic acid
Responsible Officer
Standard Reference Material
concentration causing 50% toxicity
United Nations
United Nations Environment Programme
United States
ultraviolet
World Health Organization
1. SUMMARY
1.1 Identity, physical and chemical properties and analytical methods
Palladium is a steel-white, ductile metallic element resembling and occurring with the other platinum group metals (PGMs) and nickel. It exists in three states: Pd0 (metallic), Pd2+ and Pd4+. It can form organometallic compounds, only few of which have found industrial uses. Palladium metal is stable in air and resistant to attack by most reagents except aqua regia and nitric acid.
Currently, there are no published measurement methods that distinguish between different species of soluble or insoluble palladium in the environment.
Commonly used analytical methods for the quantification of palladium compounds are graphite furnace atomic absorption spectrometry and inductively coupled plasma mass spectrometry, the latter having the possibility of simultaneous multi-element analysis.
1.2 Sources of human and environmental exposure
Palladium occurs together with the other PGMs at very low concentrations (&1 ug/kg) in the Earth’s crust. For industrial use, it is recovered mostly as a by-product of nickel, platinum and other base metal refining. Its separation from the PGMs depends upon the type of ore in which it is found.
Economically important sources exist in Russia, South Africa and North America. The worldwide mining of palladium is estimated to yield about 260 tonnes/year.
Palladium and its alloys are used as catalysts in the (petro)chemical and, above all, the automotive industries. Demand for palladium in automobile catalysts rose from 24 tonnes in 1993 to 139 tonnes in 1998, as palladium-rich technology was adopted in many gasoline-fuelled cars.
Applications for electronics and electrical technology include use in metallization processes (thick film paste), electrical contacts and switching systems.
Palladium alloys are also widely used in dentistry (e.g., for crowns and bridges).
Quantitative data on emissions of palladium into the atmosphere, hydrosphere or geosphere from natural or industrial sources are not available.
Automobile catalysts are mobile sources of palladium. Around 60% of European gasoline-fuelled cars sold in 1997 and also many Japanese and US cars were equipped with palladium-containing catalysts. Data on the exact palladium emission rate of cars equipped with modern monolithic palladium/rhodium three-way catalysts are still scarce. The particulate palladium released from a new palladium-containing catalyst ranged from 4 to 108 ng/km. These values are of the same order of magnitude as previously reported platinum emissions from catalysts.
1.3 Environmental transport, distribution and transformation
Most of the palladium in the biosphere is in the form of the metal or the metal oxides, which are almost insoluble in water, are resistant to most reactions in the biosphere (e.g., abiotic degradation, ultraviolet radiation, oxidation by hydroxyl radicals) and do not volatilize into air. By analogy to other PGMs, metallic palladium is not expected to be biologically transformable.
Under appropriate pH and redox potential conditions, it is assumed that peptides or humic or fulvic acids bind palladium in the aquatic environment. Palladium has been found in the ash of a number of plants, leading to the suggestion that palladium is more environmentally mobile and thus bioavailable to plants than is platinum.
1.4 Environmental levels and human exposure
In contrast to the large body of information concerning concentrations of metals such as lead or nickel in the environment, there is little information on palladium. Concentrations of palladium in surface water, where it is detected, generally range from 0.4 to 22&ng/litre (fresh water) and from 19 to 70 pg/litre (salt water). Concentrations reported in soil range from &0.7 to 47 ug/kg. These soil samples were all collected from areas near major roads.
Concentrations reported in sewage sludge range from 18 to 260&ug/kg, although a concentration of 4700 ug/kg has been reported in a sludge contaminated by discharges from the local jewellery industry. Drinking-water samples usually contain no palladium or &24&ng palladium/litre. The few data available show that palladium can be present in tissues of small aquatic invertebrates, different types of meat, fish, bread and plants.
The general population is primarily exposed to palladium through dental alloys, jewellery, food and emissions from automobile catalytic converters.
The human average dietary intake of palladium appears to be up to 2 ug/day.
In analogy to platinum, ambient air levels of palladium below 110&pg/m3 can be expected in urban areas where palladium catalysts are used. Therefore, the inhalative palladium uptake is very low. In roadside dust, soil and grass samples, a slight accumulation of palladium has been detected, correlating with traffic density and distance from the road.
Oral exposure in the general environment is very important and may occur by daily direct contact of the gingiva with palladium dental alloys. Skin exposure may occur by contact with jewellery containing palladium.
Dental alloys are the most frequent cause of constant palladium exposure. The corrosive behaviour of palladium-containing dental alloys in the mouth can be influenced by the addition of other metals (such as copper, gallium and indium) and processing of the alloy. Palladium-copper alloys with high copper content may be less corrosion-resistant than palladium alloys with low copper content. Palladium release from palladium-containing dental restorations shows substantial individual variation depending on the dental condition, the material involved and personal habits (e.g., gum chewing). Clinical data for iatrogenic exposure are of limited value, as the few case-studies have methodological deficiencies, such as limited numbers of tissue samples and poorly matched control groups. It is, therefore, difficult to make an accurate quantitative statement regarding daily intake, and the proposed value of & 1.5-15 ug palladium/day per person thus remains a crude estimation.
There is some information on palladium levels in the general population, where levels in urine were in the range of 0.006-&0.3&ug/litre in adults.
Most occupational exposures to palladium (salts) occur during palladium refining and catalyst manufacture. There are few exposure measurements, ranging from 0.4 to 11.6 ug/m? as an 8-h time-weighted average. No recent data are available for biological monitoring of workers exposed to palladium and its salts.
Dental technicians may be exposed to peaks of palladium dust during processing and polishing of dental casting alloys containing palladium, especially if adequate protective measures (dust extraction or aspiration techniques) are not taken.
1.5 Kinetics and metabolism in laboratory animals and humans
Only few data are available on the kinetics of metallic or ionic palladium.
Palladium(II) chloride (PdCl2) was poorly absorbed from the digestive tract (&0.5% of the initial oral dose in adult rats or about 5% in suckling rats after 3-4 days). Absorption/retention in adult rats was higher following intratracheal or intravenous exposure, resulting in total body burdens of 5% or 20%, respectively, of the dose administered, 40 days after dosing. Absorption after topical application was observed but not quantified.
After intravenous administration of different palladium compounds, palladium was detected in several tissues of rats, rabbits or dogs. The highest concentrations were found in kidney, liver, spleen, lymph nodes, adrenal gland, lung and bone. For example, 8-21% of the administered dose of palladium(II) chloride or sodium tetrachloropalladate(II) (Na2PdCl4) has been found in the liver or kidney of rats 1&day after dosing. After a 4-week dietary administration of palladium(II) oxide (PdO), measurable levels have been found only in the kidney of rats.
Only scarce data are available on the distribution of palladium from dental restorations in human tissues or fluids (e.g., in serum and saliva: about 1 ug/litre).
Transfer of small amounts of palladium to offspring via placenta and milk was seen with single intravenous doses of palladium(II) chloride in rats.
Information on the elimination and excretion of palladium is scarce and refers mostly to palladium(II) chloride and sodium tetrachloropalladate(II), which were found to be eliminated in faeces and urine. Urinary excretion rates of intravenously dosed rats and rabbits ranged from 6.4 to 76% of the administered dose during 3 h to 7 days. Elimination of palladium in faeces ranged in these studies from traces to 13% of the administered dose. Following oral administration of palladium(II) chloride, &95% of palladium was eliminated in faeces of rats due to non-absorption. Subcutaneous or topical treatment with palladium(II) sulfate (PdSO4) or other palladium compounds resulted in detectable concentrations of palladium in the urine of guinea-pigs and rabbits.
Half-lives calculated for the elimination of palladium from rats (whole body, liver, kidney) ranged from 5 to 12 days.
Mean retention values determined at three time intervals (3 h, 24&h, 48 h) in rats injected intravenously with 103PdCl2 showed little change with time for kidney, spleen, muscle, pancreas, thymus, brain and bone. They decreased slightly in liver and markedly in lung, adrenal gland and blood.
Owing to the ability of palladium ions to form complexes, they bind to amino acids (e.g., L-cysteine, L-cystine, L-methionine), proteins (e.g., casein, silk fibroin, many enzymes), DNA or other macromolecules (e.g., vitamin B6).
The affinity of palladium compounds for nucleic acids was confirmed in many studies. In vitro experiments with palladium(II) chloride and calf thymus DNA indicated that palladium(II) interacts with both the phosphate groups and bases of DNA. Several palladium-organic complexes were observed to form bonds with calf thymus DNA or Escherichia coli plasmid DNA. Most of the complexes appear to interact via non-covalent binding, mainly
in a few cases, however, indications for covalent binding were seen.
1.6 Effects on laboratory mammals and in vitro test systems
LD50 values for palladium compounds ranged, depending on compound and route tested, from 3 to &4900 mg/kg body weight, the most toxic compound being palladium(II) chloride, the least toxic, palladium(II) oxide. Oral administration caused the least toxicity. There were very similar intravenous LD50 values for palladium(II) chloride, potassium tetrachloropalladate(II) (K2PdCl4) and ammonium tetrachloropalladate(II) ((NH4)2PdCl4). Marked differences among the different routes of administration were demonstrated with palladium(II) chloride, showing in Charles-River CD1 rats LD50 values of 5 mg/kg body weight for the intravenous, 6 mg/kg body weight for the intratracheal, 70 mg/kg body weight for the intraperitoneal and 200&mg/kg body weight for the oral route. A higher oral LD50 value has been found in Sprague-Dawley rats.
Signs of acute toxicity of several palladium salts in rats or rabbits included death, decrease in feed and water uptake, emaciation, cases of ataxia and tiptoe gait, clonic and tonic convulsions, cardiovascular effects, peritonitis or biochemical changes (e.g., changes in activity of hepatic enzymes, proteinuria or ketonuria). Functional or histological changes in the kidney were found both with palladium compounds and with elemental palladium powder. There were also haemorrhages of lungs and small intestine.
Effects recorded in rodents and rabbits after short-term exposure to various palladium compounds refer mainly to changes in biochemical parameters (e.g., decrease in activity of hepatic microsomal enzymes or yield of microsomal protein). Clinical signs were sluggishness, weight loss, haematoma or exudations. Changes in absolute and relative organ weights and anaemia also occurred. One compound (sodium tetrachloropalladate(II) complexed with egg albumin) caused deaths in mice. Effective concentrations were in the milligram per kilogram body weight range. Histopathological effects have been observed in liver, kidney, spleen or gastric mucosa of rats 28 days after daily oral administration of 15 or 150 mg tetraammine palladium hydrogen carbonate ([Pd(NH3)4](HCO3)2)/kg body weight. Additionally, an increase in absolute brain and ovary weights at the 1.5 and 15&mg/kg body weight doses has been found.
The contribution of palladium to effects observed after single or short-term administration of palladium-containing dental alloy material is not clear.
There are also only scarce data available on effects from long-term exposure to palladium species (forms).
Mice given palladium(II) chloride (5 mg palladium/litre) in drinking-water from weaning until natural death showed suppression of body weight, a longer life span (in males, but not in females), an increase in amyloidosis of several inner organs and an approximate doubling of malignant tumours (see below).
Inhalative exposure of rats to chloropalladosamine ((NH3)2PdCl2) for about half a year caused slight, reversible (at 5.4 mg/m3) or significant permanent (at 18 mg/m3) changes in several blood serum and urine parameters, indicating damage mainly to liver and kidney (in addition to reduced body weight gain, changes in organ weights and glomerulonephritis). Adverse effects were also observed with enteral exposures, the no-observed-adverse-effect level being given as 0.08&mg/kg body weight.
Six months after a single intratracheal application of palladium dust (143 mg/kg body weight), several histopathological signs of inflammation were noted in the lungs of rats. Daily oral administration of palladium dust (50 mg/kg body weight) over 6 months resulted in changes in several blood serum and urine parameters of rats.
Skin tests of a series of palladium compounds in rabbits showed dermal reactions of different severity, resulting in the following ranking order: (NH4)2PdCl6 & (NH4)2PdCl4 & (C3H5PdCl)2 & K2PdCl6 & K2PdCl4 & PdCl2 & (NH3)2PdCl2 & PdO. The first three compounds caused erythema, oedema or eschar in intact and abraded skin, the next three substances elicited erythema in abraded skin and the last two were not irritant. Palladium hydrochloride (formula not specified) also caused dermatitis in the skin of rabbits.
Eye irritation was observed with palladium(II) chloride and tetraammine palladium hydrogen carbonate (but not with palladium(II) oxide), both deposited on the eye surface of rabbits. Inhalation exposure to chloropalladosamine (& 50 mg/m3) affected the mucous membranes of the eyes of rats (conjunctivitis, keratoconjunctivitis).
Some palladium compounds have been found to be potent sensitizers of the skin (palladium(II) chloride, tetraammine palladium hydrogen carbonate, palladium hydrochloride [formula not specified], palladium-albumin complexes). Palladium(II) chloride was a stronger sensitizer than nickel sulfate (NiSO4) in the guinea-pig maximization test. Guinea-pigs induced with chromate, cobalt or nickel salts did not react after challenge with palladium(II) chloride. However, if induced with palladium(II) chloride, they reacted to nickel sulfate. Somewhat divergent results have been obtained in tests studying cross-reactivity between palladium and nickel by repeated open applications to the skin of guinea-pigs. In these experiments, animals were induced with palladium(II) chloride (n = 27) or nickel sulfate (n = 30) according to the guinea-pig maximization test method and then treated once daily for 10 days according to repeated open applications testing by applying the sensitizing allergen (palladium(II) chloride or nickel sulfate) as well as the possibly cross-reactive compound (nickel sulfate or palladium(II) chloride) and the vehicle topically in guinea-pigs. In this study, it remained unclear whether reactivity to palladium(II) chloride in animals sensitized with nickel sulfate was due to cross-reactivity or to the induction of sensitivity by the repeated treatments. On the other hand, reactivity to nickel sulfate in animals sensitized with palladium(II) chloride could be attributed to cross-reactivity. Respiratory sensitization (bronchospasms) has been observed in cats after intravenous administration of several complex palladium compounds. It was accompanied by an increase in serum histamine. Significant immune responses have been obtained with palladium(II) chloride and/or chloropalladates using the popliteal and auricular lymph node assay in BALB/c mice. Preliminary data in an animal model suggest that palladium(II) compounds may be involved in induction of an autoimmune disease.
There are insufficient data on the reproductive and developmental effects of palladium and its compounds. In one screening study, reduced testis weights were reported in mice that had received 30 daily subcutaneous doses of palladium(II) chloride at a total dose of 3.5&mg/kg body weight.
Palladium compounds may interact with isolated DNA in vitro. However, with one exception, mutagenicity tests of several palladium compounds with bacterial or mammalian cells in vitro (Ames test: Salmonella typhimurium; SOS chromotest: Escherichia coli; micronucleus test: human lymphocytes) gave negative results. Also, an in vivo genotoxicity test (micronucleus test in mouse) with tetraammine palladium hydrogen carbonate gave negative results.
Tumours associated with palladium exposure have been reported in two studies. Mice given palladium(II) chloride (5 mg Pd2+/litre) in drinking-water from weaning until natural death developed malignant tumours, mainly lymphoma-leukaemia types and adenocarcinoma of the lung, at a statistically significant rate, but concomitant with an increased longevity in males, which may explain at least in part the increased tumour rate. Tumours were found at the implantation site in 7 of 14 rats (it was not clear whether the tumours were due to the chronic physical stimulus or to the chemical components) 504 days after subcutaneous implantation of a silver-palladium-gold alloy. No carcinogenicity study with inhalation exposure was available.
Palladium ions are capable of inhibiting most major cellular functions, as seen in vivo and in vitro. DNA/RNA biosynthesis seems to be the most sensitive target. An EC50 value of palladium(II) chloride for inhibition of DNA synthesis in vitro with mouse fibroblasts was 300 umol/litre (32 mg Pd2+/litre). Inhibition of DNA synthesis in vivo (in spleen, liver, kidney and testes) occurred in rats administered a single intraperitoneal dose of 14 umol palladium(II) nitrate (Pd(NO3)2)/kg body weight (1.5 mg Pd2+/kg body weight).
Palladium applied in its metallic form showed no or little in vitro cytotoxicity, as evaluated microscopically.
A series of isolated enzymes having key metabolic functions have been found to be inhibited by simple and complex palladium salts. The strongest inhibition (Ki value for palladium(II) chloride = 0.16&umol/litre) was found for creatine kinase, an important enzyme of energy metabolism.
Many palladium-organic complexes have an antineoplastic potential similar to that of cis-dichloro-2,6-diaminopyridine-platinum(II) (cis-platinum, an anticancer drug).
The mode of action of palladium ions and of elemental palladium is not fully clear. Complex formation of palladium ions with cellular components probably plays a basic role initially. Oxidation processes may also be involved, due to the different oxidation states of palladium.
1.7 Effects on humans
There is no information on the effects of palladium emitted from automobile catalytic converters on the general population. Effects have been reported due to iatrogenic and other exposures.
Most of the case reports refer to palladium sensitivity associated with exposure to palladium-containing dental restorations, symptoms being contact dermatitis, stomatitis or mucositis and oral lichen planus. Patients with positive palladium(II) chloride patch tests did not necessarily react to metallic palladium. Only a few persons who showed positive patch test results with palladium(II) chloride showed clinical symptoms in the oral mucosa as a result of exposure to palladium-containing alloys. In one study, slight but non-significant changes in serum immunoglobulins were seen after placement of a silver-palladium alloy dental restoration.
Side-effects noted from other medical or experimental uses of palladium preparations include fever, haemolysis, discoloration or necrosis at injection sites after subcutaneous injections and erythema and oedema following topical application.
A few case reports reported skin disorders in patients who had exposure to palladium-containing jewellery or unspecified sources.
Serial patch tests with palladium(II) chloride indicated a high frequency of palladium sensitivity in special groups under study. Several recent and large-sized studies from different countries found frequencies of palladium sensitivity of 7-8% in patients of dermatology clinics as well as in schoolchildren, with a preponderance in females and younger persons. Compared with other allergens (about 25 were studied), palladium belongs to the seven most frequently reacting sensitizers (ranked second after nickel within metals). Solitary palladium reactions (monoallergy) occurred with a low frequency. Mostly, combined reactions with other metals (multisensitivity), primarily nickel, have been observed.
To date, the most often identified sources of palladium sensitization for the general population are dental restorations and jewellery.
There are few data on adverse health effects due to occupational exposure to palladium. Few PGM workers (2/307; 3/22) showed positive reactions to a complex palladium halide salt in sensitization tests ( radi monkey passive cutaneous anaphylaxis test). Some workers (4/130) of an automobile catalyst plant had positive reactions in prick tests with palladium(II) chloride. A review article (without details) reported on a frequent occurrence of allergic diseases of the respiratory passages, dermatoses and affections of the eyes among Russian PGM production workers. Single cases of allergic contact dermatitis have been documented for two chemists and a metal worker. A single case of palladium salt-induced occupational asthma has been observed in the electronics industry.
Subpopulations at special risk of palladium allergy include people with known nickel allergy.
1.8 Effects on other organisms in the laboratory and field
Several palladium compounds have been found to have antiviral, antibacterial and/or fungicidal properties. Standard microbial toxicity tests under environmentally relevant conditions have rarely been conducted. A 3-h EC50 of 35 mg/litre (12.25 mg palladium/litre) has been obtained for the inhibitory effect of tetraammine palladium hydrogen carbonate on the respiration of activated sewage sludge.
Those palladium compounds that have been tested for effects on aquatic organisms have been found to be of significant toxicity. Two palladium complexes (potassium tetrachloropalladate(II) and chloropalladosamine) present in nutrient solution caused necrosis at 2.5-10&mg palladium/litre in the water hyacinth (Eichhornia crassipes). The acute toxicity (96-h LC50) of palladium(II) chloride to the freshwater tubificid worm Tubifex tubifex was 0.09 mg palladium/litre. A minimum 24-h lethal concentration of 7&mg palladium(II) chloride/litre (4.2 mg palladium/litre) has been reported for the freshwater fish medaka (Oryzias latipes). In all cases, palladium compounds had a toxicity similar to that of platinum compounds.
Toxicity tests on aquatic organisms conducted according to Organisation for Economic Co-operation and Development guidelines have been performed only for tetraammine palladium hydrogen carbonate. They resulted in a 72-h EC50 value of 0.066 mg/litre (corresponding to 0.02 mg palladium/litre) (cell multiplication inhibition test with Scenedesmus subspicatus), a 48-h EC50 of 0.22 mg/litre (0.08 mg palladium/litre) (immobilization of Daphnia magna) and a 96-h LC50 of 0.53 mg/litre (0.19 mg palladium/litre) (acute toxicity to rainbow trout Oncorhynchus mykiss). The no-observed-effect concentrations (NOECs) were given as 0.04 mg/litre (0.014 mg palladium/litre) (algae), 0.10 mg/litre (0.05 mg palladium/litre) (Daphnia magna) and 0.32 mg/litre (0.11 mg palladium/litre) (fish). All these values have been based on nominal concentrations. However, corresponding measured concentrations have often been found to be much lower and variable, the reasons for this being unclear. For the immobilization test with Daphnia magna, values based on the time-weighted mean measured concentrations have been calculated, resulting in a 48-h EC50 of 0.13 mg/litre (0.05 mg palladium/litre) and a NOEC of 0.06 mg/litre (0.02 mg palladium/litre). Phytotoxic effects have also been observed in terrestrial plants after addition of palladium(II) chloride to the nutrient solution. They include inhibition of transpiration at 3 mg/litre (1.8&mg palladium/litre), histological changes at 10 mg/litre (6 mg palladium/litre) or death at 100 mg/litre (60 mg palladium/litre) in Kentucky bluegrass (Poa pratensis). Dose-dependent growth retardation and stunting of the roots occurred in several crop plants, the most sensitive being oats, affected at about 0.22&mg palladium(II) chloride/litre (0.132 mg palladium/litre).
No information has been located in the literature on the effects of palladium on terrestrial invertebrates or vertebrates.
There are no field observations available.
2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES
AND ANALYTICAL METHODS
2.1 Identity
Palladium (Pd) belongs to the platinum group metals (PGMs), which comprise six closely related metals: platinum (Pt), palladium, rhodium (Rh), ruthenium (Ru), iridium (Ir) and osmium (Os). These metals commonly occur together in nature and are among the scarcest of the metallic elements. Along with gold (Au) and silver (Ag), they are known as precious and noble metals. Palladium is a steel-white metal, does not tarnish in air and has the lowest density and lowest melting point of the PGMs. The most important palladium compounds are listed in Table 1.
Table 1. Chemical names, synonyms and formulas of selected palladium compoundsa
Chemical name
Molecular formula
CAS registry no.
Ammonium hexachloro-palladate(IV)
(NH4)2PdCl6
Ammonium tetrachloro-palladate(II)
(NH4)2PdCl4
Bis(1,5-diphenyl-1,4-pentadien-3-one) palladium(0)
Bis(dibenzylidene-acetone) palladium
Pd(C17H14O)2
Bis(2,4-pentanedionato) palladium(II)
Bis(acetylacetonato) palladium(II)
Pd(C5H7O2)2
cis-Diamminedichloro-palladium(II)
Chloropalladosamine
(NH3)2PdCl2
trans-Diamminedichloro-palladium(II)
(NH3)2PdCl2
Diamminedinitro-palladium(II)
Pd(NO3)2(NH3)2
not available
trans-Dichlorobis-(triphenylphosphine) palladium(II)
[(C6H5)3P]2PdCl2
Dichloro(1,5-cyclooctadiene) palladium(II)
PdCl2(C8H12)
Hydrogen tetrachloro-palladate(II)
Tetrachloropalladous acid
Palladium(II) acetate
Palladium diacetate
Pd(CH3COO)2
Palladium(II) chloride
Palladous chloride Palladium dichloride
Palladium(II) iodide
Palladous iodide
Palladium(II) nitrate
Palladous nitrate
Palladium(II) oxide
Palladium monoxide
Palladium(II) sulfate
Palladous sulfate
Potassium hexachloro-palladate(IV)
Potassium tetrachloro-palladate(II)
Potassium palladium chloride
Sodium tetrachloro-palladate(II)
Na2PdCl43H2O
Tetraammine palladium(II) chloride
Tetraammine palladium(II) dichloride
[Pd(NH3)4]Cl2
Tetraammine palladium hydrogen carbonate
TPdHC Tetramminepalladium hydrogen carbonate
[Pd(NH3)4](HCO3)2
Tetrakis(triphenylphosphine) palladium(0)
Pd[(C6H5)3P]4
a 	Compiled from Degussa (1995); Aldrich (1996); Kroschwitz (1996); Lovell, personal communication, Johnson Matthey plc, August 1999.
2.2 Physical and chemical properties
2.2.1 Palladium metal
Purified metals between 99.9% and 99.999% palladium are available for chemical or medical use as foil, granules, powder, rod or wire (Aldrich, 1996). Table 2 lists atomic and crystal data as well as physical properties of palladium metal.
Table 2. Atomic and physical properties of palladium metala, b
Classification
Transition metal
Standard state
Available as foil, granules, powder, rod, shot, sponge or wire
Atomic number
Relative atomic mass
Abundance of major natural isotopesc
105 (22.3%),106 (27.3%), 108 (26.5%)
Colour/form
Steel-white, ductile metal
Electronegativity (Pauling scale)
Crystal structure
Atomic radius (nm)
Melting point (°C)
Boiling point (°C)
Exposure to heat or flame
Non- no decomposition
Density at 20 °C (g/cm3)
Reduction potential Pd/Pd2+ of aqua complexes
+0.92d (at pH 1)
Solubilitye, f
Insoluble in water (pH 5-7), acetic acid (99%), hydrofluoric acid (40%), sulfuric acid (96%) or hydrochloric acid (36%) at room temperature
Slightly soluble in sulfuric acid (96%; 100 °C) and sodium hypochlorite solution (20 °C)
Soluble in aqua regia (3:1 HCl/HNO3 at 20 °C) and nitric acid (65%; 20 °C)
Information valid for 106Pd unless otherwise noted.
Compiled from Smith et al. (1978); Lide (1992); Budavari et al. (1996).
103Pd is not a naturally occurring isotope.
Holleman & Wiberg (1995).
Degussa (1995).
For solubility in biological media, see section 6.1.
Palladium metal resists oxidation at ordinary temperatures. Palladium has a strong catalytic activity, especially for hydrogenation and oxidation reactions.
The reaction of palladium powder with oxygen may cause a fire hazard. This is particularly the case in the presence of combustible substances (e.g., carbon catalysts). On contact with palladium powder, hydrogen peroxide and other peroxides, concentrated formic acid and hydrazine are expected to decompose rapidly (Degussa, 1995).
2.2.2 Palladium compounds
Several hundred palladium compounds in various oxidation states (Table 3) are known from the scientific literature, but only a few of them are of economic relevance (see also section 3.2.4). In its compounds, palladium most commonly exhibits an oxidation state of 2. Compounds of palladium(IV) are fewer and less stable. Like the other PGMs, palladium has a strong disposition to form coordination complexes. The complexes are predominantly square planar in form. In addition, palladium forms a series of organic complexes, reviewed in Kroschwitz (1996). The organometallic palladium(II) compounds include sigma-bound alkyls, aryls, acyls and acetylides as well as pi-bound (di)olefins, alkyls and cyclopentadienyls.
Table 3. Examples of important palladium compounds by oxidation statea
Oxidation state
Electronic configuration
Pd, Pd[(C6H5)3P]4, Pd(PF3)4
[Pd(OH2)4]2+(aq), [Pd(NH3)4]2+, [Pd(NH3)2Cl2], PdF2, PdCl2, etc., PdO, [PdCl4]2-, [PdSCN4]2-, [PdCN4]2-, [Pd2Cl6]2-, salts, complexes
PdO2, PdF4, [PdCl6]2-
a 	Compiled from Cotton & Wilkinson (1982).
Physical and chemical properties of selected palladium compounds are given in Table 4.
Table 4. Physical and chemical properties of selected palladium compounds
Chemical name
Appearance
Molecular mass (g)
Melting point (°C)a
Solubility in water
Solubility in other solvents
Relative density (g/cm3)
Bis(acetylacetonato) palladium(II)
yellow crystals
NAS (1977)
Bis(dibenzylidene-acetone) palladium(0)
purple powder
NAS (1977)
Diamminedinitropalladium(II)
slightly soluble
soluble in ammonium hydroxide
Degussa (1995)
Dichloro(1,5-cyclooctadiene) palladium(II)
yellow crystals
NAS (1977)
Palladium(II) chloride
rust colour powder
675 or 501b (dec.)
soluble in hydrochloric acid, alcohol, acetone
Sax & Lewis (1987); Budavari et al. (1996)
Palladium(II) acetate
reddish-brown crystals
soluble in hydrochloric acid or potassium iodide solution
Sax & Lewis (1987); Budavari et al. (1996)
Palladium(II) iodide
black powder
soluble in potassium iodide solution
Sax (1979); Sax & Lewis (1987)
Palladium(II) oxide
black-green or amber solid
soluble in dilute aqua regia, 48% hydrobromic acid
Sax (1979); Sax & Lewis (1987)
Palladium(II) acetate trimer
gold brown crystals
soluble in acetic acid
NAS (1977)
Palladium(II) nitrate
brown salt
229.94 (anhydrous)
soluble in dilute nitric acid
Sax & Lewis (1987); Budavari et al. (1996)
Potassium chloropalladate
cubic red crystals
Sax (1979)
Potassium tetrachloropalladate(II)
reddish-brown crystals
slightly soluble in hot alcohol
Sax & Lewis (1987)
Sodium tetrachloropalladate(II)
red brown powder
NAS (1977)
Tetraammine-palladium(II) chloride
Degussa (1995)
Tetraammine palladium hydrogen carbonate
soluble (56.2 g/litre at 20 °C)
Johnson Matthey (2000)
Tetrachloropalladic(II) acid
dark brown
only stable in solution of hydrochloric acid
Tetrakis(triphenyl-phosphine) palladium(0)
yellow crystals
soluble in acetone, chlorinated hydrocarbons, benzene
NAS (1977)
trans-Diamminedichloro-palladium(II)
orange crystals
(2.7 g/litre)
soluble in ammonium hydroxide
NAS (1977)
trans-Dichlorobis (triphenylphosphine) palladium(II)
yellow crystals
NAS (1977)
a	dec. = decomposes.
b	From Sax (1979).
2.3 Analytical methods
Palladium (as a solution of palladium(II) nitrate in the mg/litre concentration range) is frequently used as a chemical modifier to overcome interferences with the determination of various trace elements in biological materials by graphite furnace atomic absorption spectrometry (GF-AAS) (Schlemmer & Welz, 1986; Taylor et al., 1998). Care must be taken, therefore, in analytical laboratories using palladium chemical modifiers to avoid contamination when measuring palladium by the GF-AAS technique.
2.3.1 Sample collection and pretreatment
Palladium is rarely found in significant concentrations in any kind of environmental material. Environmental and biological materials being investigated for very low levels of palladium need to be sampled in large amounts, with possible difficulty in homogenization, digestion, storage and matrix effects. In order to obtain enough of the analyte for accurate determinations and to separate the palladium from the sample matrix and interfering elements, preconcentration is often necessary.
Several chemical methods for the separation and preconcentration of palladium have been developed - for example, extraction with various agents, separation with ion-exchange resins, co-precipitation with tellurium or mercury and fire assay (Eller et al., 1989; Tripkovic et al., 1994). For example, palladium(II) in aqueous solution can be extracted by diethyldithiocarbamate (Shah & Wai, 1985; Begerow et al., 1997a), N-p-methoxyphenyl-2-furylacrylohydroxamic acid (Abbasi, 1987) or 1-decyl-N, N'-diphenylisothiouronium bromide (Jones et al., 1977).
Cellulose ion exchangers (Kenawy et al., 1987), 2,2'-dipyridyl-3-(4-amino-5-mercapto)-1,2,4-triazolylhydrazone supported on silica gel (Samara & Kouimtzis, 1987) or automated on-line column separation systems (Schuster & Schwarzer, 1996), were used to preconcentrate traces of palladium(II) from water samples.
For laboratories engaged in analyses of geological samples, the fire assay fusion seems to be the preferred method of dissolving and concentrating palladium. Palladium metal can be preconcentrated using either a lead collection or a nickel sulfide collection. The sensitivity of the nickel sulfide fire assay is limited by background palladium introduced by the high amounts of chemicals (e.g., nickel) employed (McDonald et al., 1994).
With biological materials, homogeneous sampling is difficult and often requires destructive methods, resulting in the loss of all information about the palladium species. In many of the analytical procedures, samples have been ashed to destroy organic materials and then treated with strong acids to yield solutions for palladium determination. Only the total content of palladium and its isotopes can then be determined. For the analysis of palladium in urine, the untreated original sample is usually unsuitable. Freeze-drying or a wet ashing procedure with subsequent reduction of volume is necessary for most analytical methods. For complex matrices such as blood, removal of the organic sample matrix combined with dilution to reduce the content of total dissolved solids is recommended to avoid blockages of the sampling cone and signal instabilities when using inductively coupled plasma mass spectrometry (ICP-MS). Strong mineral acids are most frequently applied for matrix decomposition. For blood, serum and urine digestion, ultraviolet (UV) photolysis has also been found to be useful.
2.3.2 Reference materials
The availability of certified reference materials is of great value for laboratories engaged in analytical chemistry. For palladium analysis, there are only few international standard reference materials, which are directly traceable to the Standard Reference Material (SRM) of the US National Bureau of Standards (NBS). Single-element AAS standards are offered at 1 mg/ml - for example, by Aldrich (1996) - or can be prepared according to APHA et al. (1989). To our knowledge, interlaboratory comparison programmes for the determination of environmental palladium are not yet available.
2.3.3 Analysis
Analytical methods are summarized in Table 5. Current measurement techniques do not allow separate species of palladium (metal or palladium(II) compounds) to be differentiated when more than one form is present. Almost all measurements of palladium in environmental and other samples to date have been for total palladium.
Table 5. Analytical methods for palladium determination
Matrix/medium
Sample treatment (decomposition/separation)
Determination methoda
Limit of detectionb
References
Particulate matter
air filtration through Teflon membrane
0.001 ug/m3 d
Lu et al. (1994)
Particulate matter
air filtration through Teflon membrane
0.0005 ug/m3 d
Gertler (1994)
Car exhaust
Particulate matter from exhaust pipe of cars
bubbling through nitric acid absorbent solution and filtering through ce mineralization: acid-assisted microwave digestion
quadrupole ICP-MS
3.3 ng/litre
mathematical corrections for spectral interferences
Moldovan et al. (1999); Gomez et al. (2000)
Aqueous solution
extraction with 1-decyl-N, N'-diphenylisothiouronium bromide in variety of organic liquids
&0.1 mg/litre
co-extraction of noble metals
Jones et al. (1977)
Aqueous solution
extracted by bismuth diethyldithiocarbamate into chloroform at pH 3.5
0.4 ± 0.1 ng/litre
Pd(II); 5 litres of river water were extracted
Shah & Wai (1985)
Water samples
2,2'-dipyridyl-3-(4-amino-5-mercapto)-1,2,4-triazolylhydrazone, supported on silica gel column
4 ug/litre
Pd(II); samples were preconcentrated by a factor of 100
Samara & Kouimtzis (1987)
Spring water sample
adsorption on sulfonated dithizone- direct introduction into the furnace
22 ± 2 ng/litre
Chikuma et al. (1991)
Pure waters
acidification and adsorption ont palladium is redissolved with aqua regia following ashing of the charcoal
0.3-0.8 ng/litre
1- preconcentration factor of 200
Hall & Pelchat (1993)
Groundwater
only filtration and acidification with nitric acid
5 ng/litre
convenient for determin strontium interferes with 105Pd
Stetzenbach et al. (1994)
Aqueous solution
preconcentration in a microcolumn loaded with N, N-diethyl-N'-benzoylthiourea
13-51 ng/litre
analysis of ethanol eluate
Schuster & Schwarzer (1996)
Geological materials
Rock, water
extraction with selenium via a co-precipitation technique
Eller et al. (1989)
Various geological materials
extraction with aqua regia/hydrofluoric acid, co-precipitation with tellurium
0.031 ug/ml analyte solution
determination in solution using an argon-stabilized arc
Tripkovic et al. (1994)
Various geological materials
fire assay (nickel sulfide)
Zereini (1996)
Soil and dust
Roadside dust
disso isolation by anion exchange
Hodge & Stallard (1986)
Roadside dust, soil
fire assay (nickel sulfide); digestion with hydrochloric acid
flameless AAS
appropriate for geological materials
Zereini et al. (1993)
Human blood and urine
wet ashing with nitric acid/ extraction with tri-n-octylamine from hydrochloric acid solution
flameless AAS
0.4 ug/litre
determinatio quantity 15 ml
Tillery & Johnson (1975)
Blood, urine
urine: evaporation of urine samples
blood: wet ashing with nitric acid/ extraction with tri-n-octylamine fr aspiration into air-acetylene flame
Blood: 0.9&ug/100&
urine: 0.3 ug/litre
Johnson et al. (1975a,b)
Whole blood, urine
decomposition with nitric acid/perchloric acid
flameless AAS
0.01 ug/ 0.003 ug/g urine
rapid method
(5-g blood sample)
(50-g urine sample)
Jones (1976)
direct measurement
5-ul samples
Matusiewicz & Barnes (1988)
adjustment to pH 4, conversion to the pyrrolidinedithiocarbamate complex, extraction into 4-methyl-2-pentanone
0.02 ug/litre
Begerow et al. (1997a)
acidification with nitric acid
quadrupole ICP-MS
0.03 ug/litre
no further sample treatment other than calibration
Schramel et al. (1997)
Whole blood, urine
samples mixed with hydrogen peroxide/ digestion by UV photolysis
sector field ICP-MS
0.2 ng/litre
cleaning of all materials resulted in a drastic reduction of blanks
Begerow et al. (1997b,c)
Other biological materials
dry ashing of homogenized meats (11-12 kg); decomposition with aqua regia/hydrofluoric acid
0.5 ug/kg meat
radionuclide 103Pd
Koch & Roesmer (1962)
Human organ material, blood
wet mineralization with sulfuric acid/nitric acid/ extraction with diethylammonia-diethyldithiocarbamate in chloroform
1 g organ material
Geldmacher-von Mallinckrodt & Pooth (1969)
Human hair, faeces
digestion with nitric acid/ aspiration into air-acetylene flame
20 ng/g (hair),
1 ng/g (faeces)
Johnson et al. (1975a,b)
Rice, tea, human hair
digestion with perchloric acid/ cathodic stripping voltammetric determination by mixed binder carbon paste electrode containing dimethylglyoxime
samples spiked with Pd2+ simultaneous determination of Hg, Co, Ni, Pd
Zhang et al. (1996)
Biological materials, fresh waters
extracted with N-p-methoxyphenyl-2-furylacrylohydroxamic acid in isoamyl alcohol at pH 2.7-3.5
spectro-photometry
0.1 ug/litre
enrichment of Pd(II) 15 times
Abbasi (1987)
Marine macrophytes
dry ashi purification with an anion-exchange resin
0.11 ug/kgd
Yang (1989)
Ash of plant tissue
ashing at 870 °C and digestion in hydrofluoric acid/aqua regia
0.5-1 ug/kg
Rencz & Hall (1992)
Various foods
digest calibration with rhodium and rhenium as internal standards
0.9 ug/kg (peanut oil), 0.1 ug/kg (water)
0.5-g samples
Zhou & Liu (1997)
Release from dental alloys
Cell culture medium
centrifugation
35 ug/litre
the supernate of the cell culture medium was analysed
Wataha et al. (1992)
Cell culture medium
direct measurement of cell culture extracts
20 ug/litre
Wataha et al. (1995a)
Artificial saliva
direct measurement of the solution
30 ug/litre
Pfeiffer & Schwickerath (1995)
Miscellaneous material
Diverse samples
dig separation on anion-exchange and eluants: sodium perchlorate/hydrochloric acid
1 ug/litre
Rocklin (1984)
Catalytic converter block
catalytic converter sample leached in hydrochloric acid/sodium chloride for 12 separation of the chloride complexes by electrophoresis
simultaneous determination of Pd2+ and Pt4+
Baraj et al. (1996)
AAS = atomic abs CZE-UV = capillary zone electrophoresis, using direct UV
ESA = emission spec ETA-AAS = atomic absorption spectrometry with electr FAAS = flame atomic abs GF-AAS = graphite furnace atomic abs ICP-AES = inductively coupled plasma atomic e ICP-MS = inductively coupled plas NAA = neutron UV-D = u VD = voltam XRF = X-ray f ZAAS&= Zeeman graphite furnace atomic absorption spectrometry.
The limit of detection normally represents the concentration of analyte that will give a signal to noise ratio of 2.
No information about the oxidation state is given, except it is stated that palladium(II) was determined.
Lowest value indicated.
In analytical laboratories, physical methods have widely replaced wet chemical and colorimetric analytical methods for reasons of economy and speed. Methods such as neutron activation analysis, total reflection X-ray fluorescence analysis and, above all, ICP-MS and GF-AAS are used after appropriate enrichment procedures. If palladium is brought into solution by appropriate separation methods, all PGMs can be determined in the presence of each other by X-ray fluorescence or ICP analysis, for example.
Using ICP-MS, it is possible to detect palladium in urine or blood samples of persons without occupational exposure, whereas the detection limits of AAS methods are higher by a factor of about 3 or more (see Table 5).
3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE
3.1 Natural occurrence
PGMs occur naturally in very low concentrations ubiquitously in the environment (Table 6). The fraction of palladium within PGMs is approximately 20% (Renner & Schmuckler, 1991; Renner, 1992).
Table 6. Distribution of all platinum group metals in the environmenta
Estimated concentration of PGMs
Mantle (siliceous lithosphere)
~0.05 mg/kg
Earth’s crust (attainable by mining)
~0.01 mg/kg
Hydrosphere
&10-6 mg/litre
Biomass (dry matter)
&10-7 mg/kg
a 	Adapted from Renner & Schmuckler (1991).
A concentration of palladium below 1 ug/kg in the upper continental crust is estimated. This is in accordance with a mean value of 0.4 ug palladium/kg proposed by Wedepohl (1995). Together with the other PGMs, palladium occurs at a concentration below 1 ng/kg in seawater.
3.2 Anthropogenic "sources" of palladium
3.2.1 Production levels and processes for palladium metal
Nearly all of the world’s supply of PGMs is extracted from deposits in four countries: the Republic of South Africa, Russia, Canada, and the USA. The primary production of palladium for these and other producing countries is listed in Table 7.
Table 7. Palladium output, by countrya
Palladium output (tonnes)
Soviet Union/Ru