Platinum

Platinum is a rare precious metal. It is used in the manufacture of jewellery, in vehicle catalytic converters, as a chemical catalyst, in laboratory equipment, dental implants, materials for electrical contacts and also in medicine.

How can I come into contact with this material?

Wearing of platinum jewellery is unproblematic. Platinum particles are used in many technical applications e.g. for the manufacturing of electrical switch contacts, heat conductors or thermocouples. Due to its high melting temperature and corrosion resistance it is also applied in the construction of medical and technical devices. But for all these cases there is a limited chance for direct contact with free platinum particles. 60% of the global demand for platinum is used for automotive catalysts. Since small amounts of the catalyst are being released into the exhaust stream, there is the possibility for inadvertent respiratory contact with platinum nanoparticles by inhalation of car exhaust fumes.
Cancer treatment (Chemotherapy) makes use of a specific platinum complex called Cisplatin or cis-platinum that acts toxic for both normal and cancerous cells.

Is there any risk from this material to humans and the environment?

It is possible that very small platinum particles (originating e.g. from car exhaust fumes) can be taken into the body during breathing in. These particles could then – to a certain extend – migrate from the lungs via the bloodstream to the liver where they do not cause any significant damage. In general platinum nanoparticles are considered to be non-toxic. The platinum-containing anti-cancer drug Cisplatin however offers desired toxic properties by disturbing the growth of fast growing cancer cells but affecting healthy cells as well.

Conclusion

In everyday life, there is little chance of humans or the environment to be exposed to platinum nanoparticles.

By the way…

The threshold limit value (TLV) for platinum and platinum combinations at the workplace is 2 µg/m³ per day.

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Material Information

Properties and Applications

Platinum (chemical symbol Pt) is a highly corrosion-resistant precious metal that remains very stable at high temperatures.

However, platinum also exhibits contradictory chemical behaviour. While it resists most chemicals like other precious metals, it becomes highly reactive in catalytic reactions, especially as fine particles. Platinum in the form of nanometre-sized powder is not self-igniting. Even as a finely dispersed mixture with air (dust) in the presence of an ignition source, platinum is not flammable. As a result, there is no risk of a dust explosion.

Platinum has a wide range of applications. It is used in the manufacture of jewellery, vehicle catalytic converters, laboratory equipment, dental implants and materials for electrical contacts. Industry processes platinum in the form of wires, sheets or tubes for use in electrical switch contacts, heating elements or thermocouples. Due to its high melting point and corrosion resistance, it is used in medical and technical equipment, such as trays or crucibles.

The second most important market for platinum is jewellery. This involves alloys consisting of 96 percent platinum and 4 percent copper, or 90 percent platinum and 10 percent palladium. It is used in particular for watch movements and jewellery settings. In medicine, it is used in cancer therapy, primarily as Cis-Platin (diamine dichloroplatinum; DDP, a complex-bound platinum atom).

Among the industrial applications of platinum, the use of the metal in the form of nanoparticles in automotive catalytic converters is particularly noteworthy. Numerous other chemical processes, such as the production of nitric acid, also make use of the catalytic properties of platinum nanoparticles. In fuel cells, platinum serves as an electrode material.

Platinum is a versatile catalyst. In addition to the applications mentioned above, it is also used in the production of silicones (hydrosilylation), and refineries use it to purify fuels. Platinum catalyses the selective hydrogenation of organic compounds as well as the electrochemical conversion of ammonia. In all these processes, platinum accelerates chemical reactions without being consumed in the process.

Membrane technology also makes use of platinum, particularly in the form of catalyst-coated membranes (CCMs). These are used in proton exchange membrane fuel cells (PEMFCs) and PEM electrolysers, where platinum is applied as a thin catalytic layer onto a polymer membrane. This enables efficient electrochemical reactions such as the conversion of hydrogen and oxygen into water or the electrolysis of water.

However, recent developments focus on further reducing platinum consumption by using ultra-thin coatings.

Occurrence and Production

Pure metallic platinum is now rarely mined. There are mines in South Africa, Russia, and Canada. Another source of platinum is the production of non-ferrous metals such as copper and nickel, in which the platinum group elements (palladium, rhodium, iridium, osmium, and ruthenium) are produced as by-products. After extraction, platinum is further purified using various chemical processes. In most cases, the differing solubility of platinum salts in various solvents is utilised (solvent extraction). Simply heating this product yields near-pure platinum, which is produced in the form of a nanoscale powder or platinum sponge.

Further Information

Becker, Ramona; Hartwig, Helga; Köppe, Herbert; Vanecek, Hans; Velić, Paul; Warncke, Rudolf; Zelle, Anna (1987). Gmelins Handbuch der anorganischen Chemie, 8. Auflage, Springer Berlin Heidelberg, ISBN 9783662062241.

Chen A, Holt-Hindle P. (2019). Platinum-based nanostructured materials: synthesis, properties, and applications. Chem Rev. 2010 Jun 9;110(6):3767-804. doi: 10.1021/cr9003902.

Daunderer, M (2007). Handbuch der Umweltgifte : klinische Umwelttoxikologie für die Praxis. ecomed, Landsberg/Lech, ISBN 3-609-71120-5.

Sures, B & Zimmemann, S (2005). Untersuchungen zur Toxizität der Platingruppenelemente Pt, Pd und Rh – Abschlussbericht (BWR22012) Nov 2005, Universität Karlsruhe. Programm Lebensgrundlage Umwelt und ihre Sicherung (BWPLUS), pp.37.

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Sustainability

Birds eye of turquoise and maroon water lake in nickel mine. Mindanao, Philippines. @MARYGRACE-stock.adobe.com

Production

Platinum is a rare precious metal and is primarily obtained as a by-product of nickel and copper mining. As a result, many sustainability indicators for platinum are difficult or even impossible to determine. The Republic of South Africa, the Russian Federation, and Zimbabwe are the world’s most important platinum-producing countries. Mining is carried out predominantly underground, although some operations also use open-pit methods.

Resource consumption during processing

Land use for platinum extraction is comparable to that of copper mining. Underground mining requires less surface area, as less waste rock needs to be stored. Water consumption per ton of ore extracted is high during mining operations. In addition, energy and water consumption for further processing of the ores are substantial.

Safety

Workplace safety in South African mines has steadily improved in recent years. The number of fatalities has declined. Health risks caused by dust exposure have also been reduced, resulting in fewer cases of lung disease.

Emissions

Deposits in Russia and Canada contain very high sulfide levels. During smelting, harmful sulfur dioxide is produced. For this reason, special gas-cleaning systems are used to treat the emissions. In tailings ponds, large amounts of sulfur can acidify soil and water. Therefore, measures have been established to reduce sulfur content in the waste material.

Indirect emissions generated during further ore processing must also be considered critical — primarily carbon dioxide, but also nitrogen oxides.

In South Africa and Zimbabwe, the electrical energy used for smelting platinum-bearing ores is largely generated from coal-fired power plants and is therefore associated with high CO₂ emissions.

In contrast, in vehicle exhaust catalysts, platinum helps prevent the formation of nitrogen oxides and carbon monoxide.

Social Aspects

Platinum production is controlled by a small number of large companies. As a result, only a limited number of stakeholders benefit from the profits.

According to the weighted country risk for platinum-producing countries — which incorporates the World Bank’s Worldwide Governance Indicators — approximately 80% of platinum originates from countries where government effectiveness is considered weak. These countries often face challenges related to political stability, security, voice and accountability, and corruption.

In order to ensure environmentally responsible metal production, it is becoming increasingly important within the EU to closely monitor the origin and transportation throughout the supply chain.

The German Supply Chain Due Diligence Act (Lieferkettensorgfaltspflichtengesetz) requires companies with more than 1,000 employees to document or certify compliance with social standards and occupational health and safety requirements.

Various international organizations are working on traceability systems and certification schemes for platinum, some of which are already being implemented. These aim to ensure that specific social and safety standards are upheld in mining operations.

Waste and recycling

Overall, approximately 23–27% of platinum is recycled. However, the recycling rate depends strongly on the product category.

In the jewelry sector, for example, the recycling rate is very high because pure platinum is used in jewelry. The material can be easily melted down and reprocessed.

For automotive catalysts, the recycling rate in Germany is around 50–60%. The platinum contained in them is readily accessible and, due to its relatively high concentration, can be efficiently recovered.

In certain electronic components, however, recycling is problematic. Platinum is often used in small quantities and located in hard-to-access areas, making disassembly very labor-intensive. As a result, electronic components typically achieve only a low double-digit recycling rate.

How can the material be made more sustainable?

The use of renewable energy in extraction and smelting processes could significantly reduce greenhouse gas emissions. A higher recycling rate is also achievable: recycling saves around 66% of the energy and a large share of the water consumption that would otherwise be required for mining and processing.

In addition, sustainability can be improved through compliance with social and environmental standards along supply chains. Certification schemes and legal frameworks such as the German Supply Chain Due Diligence Act play an important role in this regard.

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Human Exposure

Platinum is the element that gives its name to the so-called platinum group elements (or platinum-group metals), which also include palladium, ruthenium, and rhodium. The most common sources of exposure to platinum are industrial workplaces, automobile exhaust, medical applications, and, to a lesser extent, food or skin contact through jewelry.

Everyday contact

Platinum is found in many applications, ranging from automotive catalytic converters and jewelry to medical uses in dental alloys, implants, and cancer drugs. However, the primary source of human exposure in everyday life is particulate matter in the air. In addition to platinum, this particulate matter also contains palladium and rhodium. These materials are released in very small quantities with exhaust emissions. A 2022 study examined the concentrations of platinum and palladium in urban dust fractions in Moscow. The global concentrations of platinum cited in this study range from 0.15 ng/g to 764 ng/g. The largest amount of both platinum and palladium is bound to microparticles ..

In addition to this primary application, direct skin contact with platinum-containing jewelry is possible. Skin reactions upon contact with platinum-containing jewelry are generally rare, as platinum is considered to be very well tolerated. Nevertheless, depending on individual sensitivity and the alloy, reactions such as itching and redness may occur. Platinum alloys used in dental restorations or implants are also well tolerated.

The situation is different with drugs used to treat cancer cells. In this context, platinum (e.g., as cisplatin) is biologically very active and has a wide range of side effects.

Situation at the Workplace

In the workplace, platinum—like the other PGE—plays a role in ore extraction, dental practices, and the chemical industry. A distinction must be made between metallic platinum and platinum salts or compounds. Metallic platinum is inert and is considered to pose little risk. However, platinum salts can trigger occupational asthma (platinum asthma), which occurs primarily in the catalyst and chemical industries. A large-scale study demonstrated a quantitative correlation between the level of occupational exposure to chloroplatinate salts and sensitization. This association had already been observed in a similar manner in an earlier German study .

Consequently, different exposure limits apply in the EU—as well as in Germany and the U.S.—for metallic platinum and platinum salts, respectively. The limit value for metallic platinum dust is significantly higher at 1 mg/m³ as a time-weighted average for 8-hour shifts, 5 days a week. For platinum compounds, such as chloroplatinates, a recommended value of 2 µg/m³ applies for peak concentrations (List of MAK and BAT Values 2025; US OSHA).

Products and Customer

Platinum as a metal poses virtually no risk to consumers. The amounts found in three-way catalytic converters in automobiles are very small, and other sources of exposure are negligible. And yet, exposure through exhaust emissions from internal combustion engine vehicles does play a role in platinum exposure. A study involving three groups with different exposure patterns showed that residents of city centers had significantly higher platinum levels than the comparison groups—“rural residents” or the group exposed occupationally but not living in the city. To date, no release of platinum from dental implants or jewelry has been detected. A measurably higher excretion of platinum in urine was observed primarily in individuals with gold-platinum alloy dental fillings. The difference with platinum is similar to that with other PGE: the element’s compounds tend to have a greater effect than the metal itself, and organic complexes can be highly toxic, which is why they are also used as antitumor agents .

Platinum is generally safe. However, in certain forms—such as salts—it can trigger a type of asthma, especially in people who are frequently exposed to it, such as those working in the chemical industry.

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Environmental Release

Platinum and platinum compounds enter the environment primarily through traffic, industrial activities, and medical applications. Vehicle catalytic converters, hospital wastewater, wastewater treatment plants, and contaminated sediments are particularly relevant.

Release

Platinum enters the environment primarily through vehicle catalytic converters. It is released through abrasion and transported with exhaust emissions into road dust, and subsequently into roadside soils, sediments, surface waters, and coastal areas. Particularly high inputs have been reported in urban areas, as traffic volume and driving behaviour influence the amount released .

In addition to traffic emissions, industrial sources are considered relevant pathways of platinum release. These include mining, metal processing, electroplating, the electronics industry, vehicle component manufacturing, smelting, coal combustion, and waste from technical applications. Such sources can lead to substantial local platinum accumulation. The particles are dispersed through air, wastewater, soils, and sediments .

Platinum can be detected throughout aquatic systems, including rivers, marine environments, and aquatic organisms. In aquatic environments, platinum is found primarily in rivers, estuarine transition zones, coastal areas, sediments, and biota. Studies indicate that urban wastewater, traffic, industrial activities, and wastewater treatment plants all contribute to platinum contamination, although the relative importance of these sources may vary between regions .

Some studies do not describe specific real-world release pathways but nevertheless consider the respective substance a potential form of contamination in aquatic test systems .

Another important pathway is the use of platinum-based drugs, particularly cisplatin, carboplatin, and oxaliplatin. Following treatment, these substances or their transformation products are excreted in urine and faeces and enter rivers, coastal waters, and sediments via hospital effluents, domestic wastewater, and wastewater treatment plants. Because wastewater treatment plants do not completely remove these compounds, they may be continuously released into aquatic systems .

Released amounts

Measured platinum concentrations in surface waters are generally in the very low ng/L range. Wastewater streams can contain substantially higher platinum concentrations than natural waters. Concentrations of up to 92 ng/L have been reported in wastewater treatment plant effluents and up to 605 µg/kg in sewage treatment plant sediments .

Road dust and roadside sediments often contain higher platinum concentrations than water samples .

Solid residues such as sediments may also contain relevant platinum concentrations of up to 91 ng/g dry weight. Platinum concentrations of up to 192 mg/kg have been detected in sewage sludge and up to 602 mg/kg in waste-incineration ash .

Modern three-way catalytic converters typically contain 1.5–2.5 g of platinum. Scientists estimate the global release of platinum from vehicle catalytic converters at 14.5 tonnes per year .

For platinum-based drugs, the amounts released depend strongly on their use, dosage, and excretion. For anticancer drugs as a whole, concentrations ranging from <2 ng/L to 762 µg/L have been reported in receiving waters, while concentrations of 0.25–42.5 µg/kg have been found in sediments and sewage sludge. These values refer to the broader group of anticancer drugs and not exclusively to platinum compounds .

Results from the laboratory on release

Laboratory studies show that, under certain experimental conditions, platinum nanoparticles release only small amounts of dissolved platinum. In plant experiments with Pt nanoparticles, hardly any platinum could be detected .

Laboratory and leaching studies show that platinum from vehicle catalytic converters is released predominantly in particulate or nanoparticulate form. The soluble fraction is often below 10% and, in some cases, even below 1%. In one study, more than 99% of the platinum was described as nanoparticles. Nevertheless, a soluble fraction may form, depending on factors such as pH, catalyst age, and the presence of substances including chloride, sulfur compounds, organic matter, fulvic and humic acids, amino acids, or citrate .

Wastewater treatment plants can retain platinum-based cytostatic drugs only partially, meaning that substantial amounts may still be present in the effluent .

The most important source of platinum release is road traffic. Residues from platinum-based drugs enter the environment primarily via wastewater. Natural waters generally contain only very low concentrations of platinum.

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Uptake in Humans

Platinum nanoparticles or platinum bound to dust particles can be absorbed into the body when inhaled. They behave like particles of the same size made of other materials or like ultrafine dust. However, unlike platinum salts, the amounts of metallic platinum absorbed do not pose a risk to humans.

Uptake via the Lung

Automotive catalytic converters are the primary source of platinum exposure via the lungs. This also applies to other PGE such as rhodium and palladium. Studies show that no detectable toxic effects occur under normal environmental exposure.

A comprehensive inhalation study conducted in 2000 using various materials found no toxicological effects in rats exposed to platinum nanoparticles (18 nm). Furthermore, only a very small amount of the administered platinum was transported from the exposed lungs to the liver .

Uptake via the skin

Human skin can come into contact with platinum both in the workplace—for example, in precious metal refineries or in catalyst production—and in everyday use.

This includes direct contact with platinum salt solutions in the workplace, wearing jewelry, or having dental implants and other medical applications. However, the absorption of platinum salts through the skin (penetration) is very low and undetectable for metallic nanoparticles. Permeation of platinum nanoparticles through the skin has been observed only in damaged skin. An interesting observation regarding absorption through the skin was made in a study that compared skin samples from European women with those from dark-skinned African women. A significant difference was observed here: only a very small amount of platinum salts was transported through the skin of European women, whereas after 24 hours, nearly 10 times as much was transported through the skin of African women. Nevertheless, the amounts of platinum and its salts that can be absorbed through the skin are very low. The observed difference does not automatically imply a higher health risk ..

Uptake via the gastrointestinal Tract

Platinum and its compounds can be ingested through food and drinking water, as they occur as trace elements in the environment, particularly through emissions from automotive catalytic converters. Studies show, however, that the concentrations in food (usually < 1 µg/kg) and in drinking water (in the ng/L range) are very low. The oral bioavailability of metallic platinum is low, while soluble platinum salts are absorbed more readily but occur only in trace amounts in food. Overall, daily intake in the nanogram range is of negligible toxicological relevance. International assessments, such as those by the European “Scientific Committee on Consumer Safety (SCCS),” do not identify any significant health risk to the general population via the exposure pathways mentioned above.

The intake of platinum through food and water is of negligible health relevance due to the very small amounts involved.

Uptake via medical applications

Organic platinum compounds, particularly cisplatin and carboplatin, are used as anticancer drugs (cytostatics). The complexed platinum binds to DNA, thereby damaging rapidly growing cancer cells. These cells then die. Side effects from these drugs are significant, as the substances also damage healthy cells, particularly in rapidly growing areas such as the skin, kidneys, or hair.

In this context, however, special attention is paid to wastewater from hospitals, as the platinum compounds are excreted by patients in their urine over several weeks in virtually unchanged form. It has been demonstrated that untreated wastewater from hospitals can contain very high levels of cisplatin, and that the water only became more environmentally safe after the cytostatic drugs had been eliminated .

Although a measurable amount of platinum is released into the environment via car exhaust catalytic converters, the amount absorbed by the body is very low or virtually undetectable. However, platinum salts – in particular compounds such as cisplatin – can contaminate hospital wastewater, for example, and must therefore be treated using specialised methods.

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Uptake and Effect on Environmental Organisms

Platinum can be taken up by various aquatic organisms or adsorbed onto other surfaces. Plant roots, algae, sediment-dwelling organisms, and mussels are particularly important sites of accumulation.

Uptake

Platinum has been detected in various aquatic organisms, particularly algae, mussels, small crustaceans, worms, and fish. Platinum concentrations of up to 0.57 ng/g have been reported in macroalgae, while mussels contained more than 1.0 ng/g .

Plants take up platinum primarily through their roots, where it is also stored .

Animals living in or on sediments, such as amphipods and mosquito larvae, also take up platinum .

Residues of platinum-based drugs, such as cisplatin, have been detected in algae and aquatic plants .

Toxicity

Platinum and its compounds can be harmful to aquatic organisms. Small crustaceans such as water fleas (Daphnia magna) appear to be particularly sensitive, with studies reporting both impaired movement and reduced reproduction. Effects on survival, growth, or reproduction have also been observed in amphipods, chironomid larvae, worms, and ostracods .

Platinum-based anticancer drugs, particularly cisplatin and oxaliplatin, caused pronounced adverse effects in various aquatic organisms in several studies .

In plants and algae, the effects depend strongly on the organism, the form of platinum, and the concentration. For example, high doses of platinum nanoparticles caused no visible phytotoxic effects in garden cress and white mustard. In green algae, however, platinum nanoparticles inhibited growth and induced pronounced cellular stress. In Arabidopsis thaliana, a low concentration of Pt(II) ions even promoted growth. Higher concentrations caused leaf discoloration, tissue damage, reduced growth, impaired photosynthesis, and membrane damage .

Platinum-based anticancer drugs affect aquatic organisms by damaging DNA, inhibiting cell growth, and impairing reproduction. As a result, they may have lasting effects on entire ecosystems .

Overall, the studies show that higher concentrations cause adverse effects. However, chronic exposure may also result in significant effects at lower concentrations, including impaired reproduction, growth, behaviour, and development, as well as cellular stress.

Assessment of the effects

Most platinum concentrations measured in the environment are in the low ng/L range and are therefore well below many of the concentrations at which acute adverse effects on environmental organisms have been observed in laboratory studies. A direct acute risk can therefore generally not be inferred. However, because platinum can be taken up by algae, mussels, plants, and sediment-dwelling organisms, continued monitoring remains advisable .

Measured environmental concentrations in sediments are also generally well below the levels associated with adverse effects in laboratory studies. Nevertheless, platinum is considered relevant for sediment-dwelling organisms, as higher concentrations can impair growth and survival .

Platinum nanoparticles appear to be less bioavailable to plants than dissolved forms of platinum. Most of the platinum remains in the roots, whereas dissolved platinum salts are translocated more readily to above-ground plant tissues. Consequently, platinum nanoparticles are assumed to have a lower potential to enter the food chain .

In plants, low concentrations of Pt(II) ions may even promote growth, whereas higher concentrations are harmful .

Platinum residues from anticancer drugs are particularly relevant for risk assessment because of their persistence. Under chronic exposure, cisplatin caused effects on behaviour, reproduction, cellular stress, and development, whereas acute effects generally occurred only at higher concentrations. Because carboplatin is stable and is used in larger quantities, it is considered a substance that requires targeted removal from wastewater .

Long-term studies are important for risk assessment because effects on reproduction, development, and behaviour may only become apparent after prolonged exposure. Assessments based solely on acute effects may therefore underestimate the risk .

At typical environmental concentrations, the immediate risk generally appears to be low. However, locally elevated concentrations, long-term exposure, and platinum-based anticancer drugs are of greater concern because they can affect development, reproduction, behaviour, and cellular stress.

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Effects on Humans

Metallic platinum nanoparticles in various forms do not cause any noticeable effects and are low in toxicity. Platinum salts, on the other hand, are of concern, whilst organic platinum compounds are used as anti-tumor drugs.

Distribution and Effects in the Body

Metallic platinum is not chemically or biologically active in any form, not even as nanoparticles. High doses of platinum nanoparticles — for example, when injected into the bloodstream or administered through a tube into the stomach — can also cause complications in the body. Treatment of rats with high doses (100 mg/kg) over 30 days led to kidney and liver damage. Extrapolated to a 70 kg human, this would amount to up to 210 grams of pure platinum in the form of nanoparticles administered directly into the stomach over 30 days. As a scientific study, this provides insight into the potential effects of high concentrations. However, this is not relevant for humans in everyday life, since daily exposure in this context amounts to 10–100 ng per day — many orders of magnitude below the toxic dose.

Platinum salts, on the other hand, can trigger asthma when inhaled, a condition that persists even after exposure has ceased. A skin prick test specific to platinum salts can detect very early on whether workers are sensitive to platinum salts, allowing them to change jobs before asthma develops ..

Uptake and Effects in Cells

Laboratory studies of platinum nanoparticles and platinum salts using cell cultures have generally confirmed the results of animal studies and are consistent with observations in exposed humans.

Experiments with metallic platinum nanoparticles in cell cultures showed no acute toxicity even at ultra-high concentrations. Inflammatory reactions in the cells were only mild. It has been speculated that platinum particles could dissolve in aqueous suspensions (albeit very slowly); therefore, the effects of dissolved ions are also of interest.

Numerous studies show that dissolved platinum group elements can indeed be toxic, as they can interact with cellular DNA and thereby cause cellular damage. Even as little as 10 µmol/L of dissolved platinum can be critical for lung cells.

Although platinum nanoparticles are taken up by cells, they generally do not have a direct toxic effect there and do not enter the cell nucleus. At high concentrations, however, they can still cause DNA damage — but only because platinum ions are released from the particles. This makes it clear that it is not the particles themselves that are decisive, but rather the ions released from them, and effects occur primarily at very high concentrations .

Metallic platinum (including in the form of nanoparticles) has virtually no effect — neither in humans, nor in animal studies, nor in cell cultures. Dissolved platinum salts, on the other hand, can trigger allergic reactions such as asthma in humans.

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Environmental Distribution

Depending on its form, platinum is transported in dissolved, particulate, or nanoparticulate form. It can be dispersed through the atmosphere, stormwater runoff, rivers, wastewater, and sediments. Its mobility is influenced by water chemistry, salinity, pH, and organic matter.

Transport

Platinum from vehicle catalytic converters is released primarily through exhaust emissions and road dust. From there, it can enter soils, rivers, and coastal waters via atmospheric transport, rainfall, surface runoff, and sediments. Elevated platinum concentrations have been detected in road dust, roadside soils, and tree bark, particularly near heavily trafficked roads and in areas with frequent stop-and-go traffic .

In aquatic environments, platinum is transported both in dissolved form and bound to particles. Some of it can bind to organic matter and subsequently settle into sediments, allowing contaminated sediments to act as long-term reservoirs. In the estuaries studied, tides, wind, river discharge, and salinity influenced its distribution. Both systems were identified as potential sources for the further transport of dissolved platinum into coastal waters .

Platinum residues from anticancer drugs enter hospital and municipal wastewater through urine and faeces. There, they are diluted and transported further .

In soils, platinum mobility depends strongly on its chemical form and soil properties. Dissolved Pt(II) ions are more mobile than platinum nanoparticles. Organic layers and mineral surfaces can bind the nanoparticles and therefore retain them more effectively. Platinum mobility is influenced by porosity, pH, particle size, and soil type .

In water and other liquids, platinum nanoparticles remain largely stable or form aggregates .

Transformation

Platinum can occur in the environment in different forms. Metallic platinum and platinum nanoparticles are generally poorly soluble. Under certain conditions, they can slowly transform into dissolved forms. This transformation depends on factors such as pH, salinity, chloride, sulfur compounds, and natural organic matter. Depending on the environmental conditions, platinum ions can bind to various other substances .

Residues of platinum-based anticancer drugs differ markedly in their stability. Cisplatin transforms relatively rapidly in water, urine, and test media through ligand-exchange reactions, forming reactive transformation products. Carboplatin, in contrast, remains unchanged for considerably longer and has often been detected as the intact compound in urine and wastewater-like samples. Oxaliplatin can form various degradation products and undergoes more extensive transformation at higher chloride concentrations .

In organisms, platinum compounds can react with sulfur-containing biomolecules, such as glutathione or metal-binding proteins. This binding may partially detoxify platinum and reduce its availability for reactions with DNA. At the same time, reactive cisplatin transformation products can bind to DNA and thereby induce biological effects .

Platinum can accumulate locally in soils and sediments or spread in dissolved form through aquatic systems. Risk assessment must also consider the persistence of carboplatin and the transformation products of cisplatin and oxaliplatin.

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Literature