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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ContiTech, a group sector of Continental, has officially launched production at its new USD 90-million hydraulic hose manufacturing facility in Aguascalientes, Mexico. This significant investment is a strategic move to reinforce local supply chains, boost regional production capacity and position innovative fluid power solutions closer to its customer base across North America.

The new 900,000-square-foot plant will produce high-performance hoses for numerous industrial and mobile applications, serving vital sectors such as construction, agriculture, mining and energy. It has been designed to operate in a tightly coordinated network with ContiTech’s existing facility in Norfolk, Nebraska. This dual-plant strategy enhances production flexibility, improves operational efficiency and allows the company to be more responsive to evolving customer demands by strategically balancing technology, volume and lead times.

This expansion underscores ContiTech's long-term commitment to growth in key markets through substantial investment in local infrastructure and talent. Production at the Aguascalientes site will be gradually increased, with the first customer deliveries anticipated to commence in the fourth quarter of 2025.

Philip Nelles, Member of the Continental Executive Board and CEO of the ContiTech group sector, said, “The start of production in Aguascalientes marks a key milestone in ContiTech’s journey towards being a more agile, regionalised partner to our customers. At ContiTech, we build on 150 years of materials expertise. While our portfolio is broad and diverse, all our solutions are grounded in the same strength: high-performance materials that are mission critical, innovative and engineered to perform. Whether they connect, convey or cover, our products play essential roles across industries and applications.”

Andreas Gerstenberger, CEO of ContiTech USA and Head of Business Area Industrial Solutions Americas, said, “We are ready to lead in this segment. This new plant reflects our commitment to both innovation and proximity. With our customers increasingly looking for responsive and innovative solutions, we are proud to deliver with local production, advanced technology and a skilled workforce. More than just expanding our footprint, this investment is about creating mutual value with our customers, partnering closely to help them succeed in their own markets. By placing customer needs at the centre of everything we do, we aim to be their first choice for material-driven solutions, now and in the future.”

Vipal Rubber, a leading global producer of retreading rubber, has reaffirmed its commitment to innovation with the launch of its new V SUPER HYBRID technology. Available from 1 March 2025, this new compound is designed to redefine performance standards for mixed-terrain applications, offering enhanced mileage, durability and resistance for retreaded tyres across various fleet sizes.

The V SUPER HYBRID achieves a superior balance between on-road and off-road performance. It has proven effective in demanding sectors such as logging, grain and livestock transport, demonstrating robust capabilities across diverse operating conditions. Key advantages of the innovation include improved resistance to chipping and punctures, enhanced casing protection that extends tyre service life, lower environmental impact through increased tread utilisation and significant operational cost savings for fleet operators.

Field tests substantiate these claims. In one trial involving a high-torque truck on steep, unpaved terrain, tyres with V SUPER HYBRID technology showed an 11.5 percent increase in mileage over a standard market compound while maintaining structural integrity with no signs of breakage. Furthermore, the same technology demonstrated the potential for up to a 140 percent mileage increase over conventional compounds in continued testing. The tread's regular wear pattern also allowed for better depth utilisation, enabling tyres to remain in operation down to 5-6 mm, compared to the previous limit of 12 mm. Another test with a grain and livestock truck confirmed these results, documenting a 12.5 percent performance gain across different tread designs.

Kuraray Asia Pacific Pte. Ltd., a subsidiary of Kuraray Co., Ltd., has inaugurated the Kuraray Asia Pacific Centre in Singapore's Science Park. This new facility will function as a dedicated technical support hub for the Asian market. Its primary focus will be on providing specialised expertise for growing regional demand in PVOH resin, EVAL EVOH resin and activated carbon products.

Equipped with advanced material evaluation and analysis laboratories, the centre is designed to deliver prompt and tailored solutions to meet specific local customer requirements. It will also act as a platform for open innovation, fostering collaborative development and product demonstrations to generate new value.

By establishing itself within the concentrated research environment of the Singapore Science Park, the centre aims to accelerate market development and attract global talent through strategic partnerships. This initiative is a key part of the Kuraray Group's strategy to address emerging customer needs, explore new applications and strengthen its overall business expansion throughout the region.

Lim Wey-Len, Executive Vice President, Singapore Economic Development Board, said during the opening ceremony on 1 September: “We welcome Kuraray and other like-minded companies to leverage Singapore’s innovation ecosystem, talent pool, and regional connectivity to scale impactful and sustainable solutions from here.”

Tomoyuki Watanabe, Director and Managing Executive Officer, and President of the Vinyl Acetate Resin Company at Kuraray, said, “By offering a place for co-creation with our customers, we hope to drive the rapid market growth in the region.”

The Association of Natural Rubber Producing Countries (ANRPC) has released its Monthly NR Statistical Report for July 2025, providing an overview of key developments in the global natural rubber sector.

According to the report, natural rubber prices exhibited significant volatility in July. This instability was driven by a combination of adverse weather conditions impacting production, ongoing geopolitical tensions and international trade tariffs. After an initial phase of ample supply and muted demand, market sentiment shifted as concerns over potential supply disruptions prompted a notable increase in purchasing activity.

The report further projects a modest global production increase of 0.5 percent for 2025, while demand is anticipated to grow by a slightly higher 1.3 percent. However, this growth is expected against a challenging backdrop of a potential global economic slowdown. Complex US tariff policies and their widespread ripple effects are primary factors contributing to what may become one of the most subdued years for economic expansion since the pandemic.