Recently, models on the fate of tyre wear particles (TWPs) have estimated that 18% of TWP emissions are transported from roads to freshwater bodies and approximately 2% are led out to estuaries and then marine habitats. What then happens to the remaining 16% of TWP emissions left in the freshwater compartment is not yet clear

 

The presence of tyre wear particles (TWP) in the aquatic environment is considered an emerging contaminant, and one that has gained increasing interest during the past few years. Although the presence of TWPs in the environment is given greater attention these days, TWPs have probably been present since the dawn of the pneumatic car tyre production in the late 19th century. The first scientific report of tyre dust identification along a roadside was published in 1961. Different perspectives have since been applied to this field of research and almost decade by decade shifted foci from degradation patterns to heavy metal release, to impacts of scrap tyres on the aquatic environment and leaching of chemicals from tyres. More recently, research within this field has been directed towards repurposing scenarios using crumb rubber in turf fields and playground material. Finally, in the 2010s, micronised tyre rubber has become grouped with other polymer debris and hence become part of the polymer landscape usually referred to as ‘microplastics.’ TWPs are considered to represent the majority of microplastics (or polymer debris) in the environment, and the newest calculation on the wear of tyres is estimated at 0.81 kg per person per year.

Now, looking at TWPs through the lens of microplastic pollution, research and information from the microplastics field are very well applicable to TWPs in many instances. With this new perspective of TWPs, increasing awareness of possible adverse effects in the environment follows - how do TWPs distribute in the different environmental compartments (soil, air, sediment, water and biota (living organisms)) and how do TWPs behave when exposed to different abiotic factors in these environmental compartments. For example, UV-radiation or pH, temperature and salinity differences could affect TWPs, but to what degree? A recent paper on this very subject concluded that particularly temperature and mechanical stress could influence the toxicity of TWPs. The focus of tyre production and function have seemingly always been directed towards maximising the three hallmarks: grip, wear and rolling resistance, and rightfully so, but somewhere along the road we forgot to consider where tyre abrasion actually disappears to. Luckily, some scientists already thought of this and today we can begin to lay the foundation to our collected TWP knowledge, based on the available scientific literature.

 

From roads to water

Research shows that the minority of TWPs end up in the airborne fraction (0.1-10%) and recently TRWPs have been assessed to contribute a low risk to human health in the particulate matter (PM) PM2.5 and PM10 range. So, where to find the remaining 90.0-99.9% of tyre debris emissions? Early research on particulate distribution showed a decreasing concentration of TWPs with increasing distance from the road. From there, TWPs are expected to wash off during rainfalls, transporting them to different environmental compartments. Recently, models on the fate of TWPs have estimated that 18% of TWP emissions are transported from roads to freshwater bodies and approximately 2% are led out to estuaries and then marine habitats. What then happens to the remaining 16% of TWP emissions left in the freshwater compartment is not yet clear and more research is needed to answer this question.

Aquatic organisms living in the water column or the sediment can interact with TWPs in their natural habitats during this particle transportation through freshwater to the marine environment. Although there are no scientific references on field observations of TWP ingestion by aquatic biota yet, few recent observations of this behaviour under controlled laboratory settings have been reported. In 2009 the first observation of the water flea, Daphnia magna, ingesting TWPs was described in the scientific literature and only two years ago the first photos were published showing ingestion of TWPs in the benthic amphipod Gammarus pulex following sediment exposure. Shortly thereafter photos of TWP ingestion in the amphipod Hyalella azteca and opossum shrimps from the mysidae family followed after water-only exposures, and most recently freshwater and marine fish species have been documented ingesting TWPs under laboratory conditions.

The recent focus on particulate effects of TWPs on biota is still in its infancy and the latest development in this field investigates the possible effects of both the particulate fraction and the leachate fraction. The leachate fraction is the suite of chemicals that leach out from TWPs to the surrounding water. Previously, tyre toxicity investigations in the aquatic environment revolved solely around the leachate fraction, which has been the primary focus over the last 30 years. Among the first papers the effect of whole tyre leachate was investigated showing worn tyre leachate to exhibit greater toxicity than leachate from a pristine tyre to rainbow trout. Furthermore, decreasing toxicity was observed with increasing salinity indicating that salinity either influences the leachability of toxic constituents or that an interaction of salts and toxic chemicals is present. Exposure of shredded tyre chips to different bacteria likewise showed a correlation between decreasing toxicity and increasing salinity, concluding that tyre leachate is likely to be a greater threat to freshwater habitats than to estuarine or marine habitats.

Toxicity pattern

Further testing of TWPs and leachate on a freshwater species recently showed a dissimilar toxicity pattern when comparing acute toxicity responses of TWPs or leachate. Here, the amphipod H. azteca was exposed to either TWPs in freshwater or the leachate fraction alone, i.e. with no particulates present. This showed that leachate was more toxic in lower concentrations, presumably because dissolved chemicals are more bioavailable. Although, at higher concentrations, the particle fraction of TWPs became more toxic. This phenomenon very well describes the complexity and discrepancies when working with TWPs in the aquatic environment. It is not just a question of determining toxicity of a single chemical under controlled settings, but rather investigating a mixture of many chemicals in changing ambient environments. This complex matrix of polymer and chemicals can be more or less bound to the particle, which in itself might have adverse effects. However, the particle could also function as a vessel, containing chemicals and making them more or less bioavailable depending on the surrounding environment. Discovering exactly which chemicals leach out under different exposure scenarios, and most importantly, what of that is actually bioavailable to aquatic living species is the more interesting question to answer.

Due to the amorphous nature of rubber, end-of-life tyres (ELTs) have been used as leachate collection material and been used to collect polycyclic aromatic hydrocarbons (PAHs) and metals from contaminated waters. This discrepancy between the different TWP uses that in some cases could deem toxic and have adverse effects but at the same time might serve to mitigate other environmental issues is a great conflict of contradictory traits. Now, we need to unravel exactly when these contradictory traits are possibly affecting aquatic environments negatively and when these traits might be used for our advantage.

 

So how do scientists quantify TWPs and chemical constituents or ‘biomarkers’ from TWP leachate in water? The quick answer is that no tried and tested procedure is more right than any other now, we simply do not have conformity or guidelines on how to do this. Especially when looking to find particulates from tyre debris, as this is not usually detected when investigating for other polymer debris e.g. microplastics. Therefore, it is expected that the total amount of microplastics has been underestimated due to the lack of data from TWPs, which make up a large part of the estimated microplastic load worldwide and have not been reported on a regular basis. A multitude of methods have been used to estimate TWP emissions by measuring the concentration of chemicals in samples, with more or less success over the years. The biomarkers that have been used to determine TWP concentration most successfully include quantification of benzothiazoles and zinc. Both chemicals are used as part of the vulcanisation process and are also ubiquitous in nature. They are used for manufacturing of other materials, but specific versions can be attributed mainly to tyre manufacturing and are thus the most reliable compounds to measure.

How this emerging field of tyre ecotoxicology will progress ultimately depends on cooperation between different stakeholders having a common goal to pursue. The one thing that we can probably all agree on, is the need for tyres and other rubber products in our society. How we then fill that need, and what future decisions we make to maximise our understanding of the possible negative implications of TWPs in the aquatic environment is of paramount importance. Our job now is to continue our research within this field and ultimately prevent excess and unnecessary pollution of the water bodies that we all depend on, in a manner that stays true to both the environment and our need for safe and reliable tyres. 

*The author is a PhD student in Environmental Biology at Roskilde University, Department of Natural Science and Environment, Denmark, with funds from Danish Environmental Analysis

 

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Yokohama Rubber completed enforcement action to halt the production and distribution of counterfeit versions of its “ADVAN Racing” aluminium wheels in China following a coordinated investigation with local authorities.

The Japanese tyre and wheel manufacturer filed an administrative complaint with the Municipal Administration for Market Regulation in Anlu City, Hubei Province, after uncovering a local manufacturer producing unauthorised copies of its high-performance wheels for sports cars.

Authorities in Anlu conducted a raid at the site in November 2024, seizing all counterfeit wheels. A subsequent investigation led to the identification of another company that had commissioned the counterfeit production. Administrative penalties were imposed on the ordering party, including a fine and an order to cease all illegal activity and surrender any remaining fake products.

This marks Yokohama Rubber’s latest successful enforcement action in China. The company had previously filed complaints targeting distributors of counterfeit wheels, resulting in the removal of fake products from the market.

“Yokohama Rubber remains resolute in its stance against the infringement of intellectual property rights, including the production and sale of counterfeit goods, and will strengthen its efforts against such illegal activities in Japan and overseas to ensure that its customers around the world are confident and secure in the knowledge that they are using genuine YOKOHAMA products,” the company said in a statement.

Japanese chemical manufacturer Tosoh Corporation announced plans on Wednesday to construct a second chloroprene rubber production facility at its Nanyo Complex, representing an investment of approximately ¥75 billion (£460 million) to meet rising global demand for the speciality polymer.

The new facility, scheduled to begin construction in spring 2027, will add 22,000 metric tonnes of annual production capacity for Tosoh’s SKYPRENE chloroprene rubber brand. Commercial operations are expected to commence in spring 2030 at the Shunan City site in Yamaguchi Prefecture.

Chloroprene rubber serves as a critical component across multiple industries, from automotive manufacturing to medical applications. The synthetic rubber’s popularity stems from its exceptional resistance to oil, weather conditions, and flame exposure, making it suitable for demanding applications, including automotive hoses, industrial belts, adhesives, and medical gloves.

The expansion comes as global demand for high-performance polymers continues to grow, driven by increasing automotive production and stricter safety requirements across industrial sectors. Medical applications have also seen increased demand following heightened awareness of the requirements for protective equipment.

Tosoh’s decision to double down on chloroprene rubber production reflects the material’s position within what the company terms its “Chemical Chain Business” - a strategy focused on value-added speciality chemicals rather than commodity products.

The investment represents one of the larger capacity expansion projects announced by Japanese chemical companies this year, signalling confidence in long-term demand fundamentals despite current global economic uncertainties.

The Nanyo Complex already houses Tosoh’s existing chloroprene rubber operations alongside other chemical production facilities. The site’s established infrastructure and logistics capabilities influenced the decision to expand at the existing location rather than develop a greenfield facility.

Industry analysts note that the three-year construction timeline reflects the technical complexity of chloroprene rubber production, which requires specialised equipment and stringent safety protocols due to the chemical processes involved.

The expansion aligns with broader trends in the Japanese chemical industry, where companies are increasingly focusing on high-margin speciality products to offset competitive pressures in traditional commodity chemicals from lower-cost Asian producers.

Epsilon Carbon, a leading global manufacturer of carbon black, has launched N134, which it claims is a specialised ‘Hard Grade’ carbon black known for its superior abrasion resistance and durability.

At present, the high-quality N134 grade is being imported due to the lack of consistent quality and supply chain issues in the Indian market. As a result, the tyre makers have to modify their formulations using other grades of carbon black, which it shared often leads to reduced performance.

But now, Epsilon Carbon has become the first company in India to install a dedicated manufacturing unit designed for N134 grade hard carbon. The company is expanding its existing Vijayanagar Carbon complex facility to produce 215,000 tonnes of carbon black.

This will not only ensure consistent supply of N134 carbon black for tyre makers in the country, reduce import dependency, but also open up export potential to markets such as Europe and USA. Epsilon Carbon will also focus on integrate advanced processing techniques to ensure batch consistency for durability and performance.

Vikram Handa, Managing Director, Epsilon Carbon, said, “This is a proud moment for us and for India’s carbon black manufacturing sector as the high quality N134 black will significantly reduce import dependency and provide tire manufacturers in India and abroad with a reliable, high-quality product. Our goal is to match global standards while building India’s capability to serve premium markets.”

Lummus Technology, a leading provider of process technologies and energy solutions, has signed a memorandum of understanding (MoU) with InnoVent Renewables to collaborate on the global licensing and deployment of InnoVent’s continuous tyre pyrolysis technology.

Under the proposed agreement, Lummus will become the exclusive licensor for InnoVent’s proprietary pyrolysis process, which transforms end-of-life tyres into valuable outputs, including pyrolysis oil, gas, recycled carbon black and steel. Additionally, Lummus will offer integrated technology packages that combine InnoVent’s pyrolysis system with its own downstream processing solutions, enhancing the value of fuel and chemical products derived from waste tyres.

InnoVent’s technology provides a fully scalable, end-to-end solution for converting discarded tyres into renewable fuels and high-value petrochemicals, covering everything from pre-processing to purification. The company currently operates a commercial-scale facility in Monterrey, Mexico, with an annual processing capacity of up to one million passenger tyres, and has the capability to expand further.

Leon de Bruyn, President and Chief Executive Officer, Lummus Technology, said, “This is another significant step in expanding and strengthening our portfolio for the circular economy. By combining InnoVent’s tyre recycling technology with Lummus’ global licensing and engineering expertise, we will be addressing the global challenge of waste tyres and creating new pathways for sustainable product development.”

Vibhu Sharma, Chief Executive Officer, InnoVent Renewables, said, “Partnering with Lummus has the potential to accelerate the global deployment of our technology and help us address the environmental and public health challenges of one billion end-of-life tyres that are disposed of annually. Together, we can transform waste into valuable resources, reduce carbon emissions and support the transition to a more sustainable future.”