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

References

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Birla Carbon has confirmed a price increase of up to 15 percent for its Speciality Materials products across Asia, scheduled to take effect on 1 October 2026. The company pointed to significant and sustained rises in feedstock costs, driven partly by ongoing geopolitical instability and disruptions in global feedstock markets, as the reason behind the adjustment.

Although Birla Carbon pursued operational efficiencies, supply chain optimisation and disciplined cost management to soften the impact, the scale and persistence of the cost escalation left a price adjustment unavoidable. The company's sales teams will engage customers directly to explain the details and help them navigate the transition.

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ACE Laboratories, an independent ISO/IEC 17025-accredited polymer testing laboratory, has partnered with Abdallah Consulting, LLC, a prominent tyre pyrolysis advisory firm, to introduce VericarbSM. This independent certification programme verifies that materials marketed as recovered carbon black (rCB) meet established criteria for rCB.

Recovered carbon black, derived from end-of-life tyres via pyrolysis, serves as a sustainable substitute for virgin carbon black in rubber and polymer applications. However, the emerging market has lacked the standardisation and independent verification that established supply chains provide. VericarbSM addresses this gap through independent material characterisation and rubber performance data, offering stakeholders a consistent basis for evaluating rCB products.

For producers, certification accelerates market entry and improves buyer approval rates. Consumers gain more capable suppliers and reduced evaluation time, while investors benefit from clearer volume sizing and fewer costly test failures. The programme is jointly administered by both organisations.

Erick Sharp, CEO, ACE Laboratories, said, “The rCB market has enormous potential, but growth has been held back by uncertainty about material quality and consistency. VericarbSM gives producers a way to prove their product and gives buyers the independent data they need to say yes.”

Dave Abdallah, Founder, Abdallah Consulting, said, “One key reason for the delayed growth of recovered carbon black is lack of product performance information in the customer’s language. ASTM standards are critical; in fact, most testing done in the process follows ASTM methods. But customers relate to a product better when its performance is shown in applications relevant to them. VericarbSM solves the language issue by showing verified rCB in terms of rubber performance while simultaneously adding credibility via third-party analysis and reporting.”

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Zeon Corporation established Zeon Chemicals Kurashiki Co., Ltd. on 23 July 2026 to take over the acrylic rubber operations of fellow group firm Tohpe Corporation. The new entity, headquartered in Kurashiki City, Okayama Prefecture, is wholly owned by Zeon with paid-in capital of JPY 10 million and is led by representative Koji Minami.

On 21 August, Tohpe and the new subsidiary signed an absorption-type company split agreement, prompting Zeon to begin the procedures required under the Companies Act. Operations at the new company, focused on manufacturing and selling acrylic rubber and related activities, are scheduled to commence on 30 October 2026.

Acrylic rubber, known for its heat resistance, is used in automotive components including oil seals and hoses. The Zeon Group already maintains four production sites across Japan, United States and Thailand, forming a global supply network for the material.

The restructuring follows Zeon’s 11 May 2026 announcement that it would transfer Tohpe shares to NATOCO Co., Ltd. of Miyoshi City, Aichi Prefecture, as part of Tohpe’s paints business divestiture. Tohpe’s acrylic rubber operations, which complement Zeon’s Elastomers Business, will now be positioned as a key specialty rubber manufacturing site, with closer operational coordination intended to strengthen Group competitiveness and corporate value.

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The company is betting that a polymer manufactured from end-of-life truck tyres can disrupt the market for petroleum-based styrene-butadiene-styrene (SBS), a widely used road-binding additive whose pricing and availability are tied to global oil markets. After completing a live road trial with Road Science and Auckland Transport in New Zealand, the company is preparing to use the results as a springboard for expansion into Australia and Sub-Saharan Africa, positioning the recycled material as a lower-cost, lower-carbon alternative to virgin polymers.

New Zealand-based Revyre Global Limited is positioning a polymer manufactured from end-of-life truck tyres as a lower-cost alternative to petroleum-based styrene-butadiene-styrene (SBS) after completing a live road trial with Road Science and Auckland Transport in New Zealand.

The company has spent several years developing the product as a direct replacement for SBS. Unlike conventional tyre-derived asphalt, which relies on crumb rubber, the company’s Chief Executive Officer Shaun Zukor told Tyre Trends that its proprietary thermomechanical process produces a remanufactured polymer with blending characteristics similar to SBS, allowing it to be used in existing asphalt infrastructure.

“Our primary objective was to develop a drop-in replacement for SBS, which is a petroleum-derived synthetic polymer,” Zukor said. “SBS is expensive, made from virgin materials and is widely used to improve road durability, fatigue resistance and overall pavement performance.”

The company began engaging Road Science, a division of Downer, and Auckland Transport after completing laboratory validation with engineering consultancy WSP in New Zealand.

Before approaching customers, it invested around 18 months in laboratory testing to validate the material’s performance.

Following successful laboratory trials, Road Science carried out its own evaluations before, together with Auckland Transport, deciding to trial the material on Blockhouse Bay Road, one of Auckland’s busiest roads.

The project then underwent another lengthy approval process involving Auckland Council and scientific advisers.

“It took another year to a year and a half to obtain all the necessary approvals from the council and its scientific advisors,” Zukor said. “They wanted to verify that all the claims in our technical literature were accurate.”

Construction of the trial road took place over three days in March and the company expects to receive the first performance data around September. Those results are expected to support commercialisation in overseas markets.

“Our business is focused only on New Zealand at the moment because we’re using it as a proof of concept,” Zukor said. “Once those results are available, we’ll publish them. That will place us in a much stronger position to take the product into Australia and Sub-Saharan Africa.”

The company estimates that entering Australia would take another 12 to 18 months after trial results are available and a planned New Zealand manufacturing facility becomes operational.

Although the current road project used only a small quantity of material because it is a demonstration, Zukor said the commercial opportunity could expand significantly.

“We used a relatively small amount of material for this particular project, but if the opportunity grows as expected, supplying the Auckland Transport network alone could eventually consume between 40–50 percent of our production capacity,” he noted.

MATERIAL ECONOMICS

The company currently manufactures the material primarily from truck and bus radial (TBR) tyres and earthmover tyres because of the higher natural rubber content.

While the SBS substitute represents the company’s immediate focus, it has divided its broader product portfolio into three categories. Revpol A, manufactured mainly from passenger and light truck tyres is intended for lower-performance rubber products such as rubber tiles, shoe soles and conveyor belts.

Revpol B targets asphalt applications and new tyre manufacturing, while Revpol C, produced largely from earthmover tyres, is designed for higher-performance applications.

The company is not currently manufacturing at its own facility but plans a new production unit in New Zealand. Until that facility is operational, product for trials is being supplied by its Canadian partner.

The technology relies primarily on a thermomechanical recycling process rather than chemical recycling. Whole tyres are broken down with steel separated from the rubber before the rubber is processed to a 30-mesh particle size and passed through Revyre’s proprietary thermomechanical process.

Zukor said only a very small amount of non-toxic, FDA-approved chemicals are used and that the process is driven primarily by operating parameters rather than chemical reactions.

He added that one of the key advantages of the technology is that it can be incorporated into existing SBS blending infrastructure with minimal changes as most development work focused on determining the optimum blending ratio rather than overcoming technical limitations.

“The primary technical challenges relate to the blending ratio,” he said, adding, “The higher the percentage of Revpol you add, the higher the temperatures and shear forces required in the bitumen blending terminals.”

Although the company has successfully blended as much as 20 percent Revpol into bitumen during development, Zukor said performance gains diminish beyond a certain point.

It has identified an optimum blend of between 5 percent and 10 percent depending on the application, ranging from conventional roads to heavy-duty pavements and airport runways.

“Any facility that currently blends SBS using its existing infrastructure can also blend our product using that same infrastructure,” he said.

CATALYST FOR SAVINGS

Zukor believes the material can reduce both costs and environmental impacts while improving pavement performance.

“We want to create a product that is environmentally sustainable, has an abundant raw material supply and is 20–40 percent cheaper than virgin materials while also having a significantly lower carbon footprint,” he stated.

Laboratory testing has produced encouraging results. According to Zukor, New Zealand’s wheel-tracking standard requires materials to withstand 800,000 load cycles, while Revyre’s product continued to perform until testing was halted at two million cycles.

“Our product achieved nearly two to three times the required wheel-tracking performance compared with standard bitumen,” he noted.

He also added that the objective is to produce road surfaces that are less expensive, more durable and environmentally sustainable while simultaneously addressing the challenge of managing end-of-life tyres.

“We believe this product ticks all of those boxes and have obtained a patent for it,” he said.

MANUFACTURING SCALABILITY

Although the company is currently relying on manufacturing capacity in Canada, Zukor said its modular production model could support significant expansion once commercial demand develops.

“We can currently produce up to 10,000 tonnes of this product, but because our production facilities are modular, capacity can easily be scaled anywhere from 1,000 tonnes to 50,000 tonnes, depending on market demand and the requirements of a particular region,” said Zukor.

Once the planned New Zealand facility becomes operational, Zukor expects its tyre feedstock to be supplied through Tirewise, the country’s extended producer responsibility (EPR) scheme for end-of-life tyres.

Under the programme, every imported tyre attracts a levy that funds incentives for registered collectors, processors and end users to move tyres through the approved recycling chain. Zukor said Revyre intends to register again as a processor after commissioning its new plant.

GOING PAST HURDLES

Zukor acknowledged that customer adoption remains the biggest hurdle. Road contractors also need to validate new formulations through laboratory testing before incorporating them into their pavement designs. Hence, Revyre is focusing on multinational contractors already operating in New Zealand to accelerate adoption, believing successful validation locally could support deployment elsewhere within those organisations.

He also believes global dependence on petroleum-derived SBS strengthens the case for tyre-derived alternatives.

“If you look at SBS, it’s already a product that’s in very high demand globally. Because it’s petroleum-based, its availability and pricing are heavily influenced by global macro-economic and geopolitical events,” Zukor said.

He said the company’s commercial proposition rests on three principles viz-a-viz consistent quality, supply and pricing.

According to Zukor, replacing virgin SBS with tyre-derived polymers could help localise supply chains, reduce exposure to petroleum price volatility and improve environmental outcomes while lowering costs for road owners.

Beyond New Zealand, Revyre is also evaluating opportunities in North America through its Canadian partner and is exploring future markets for tyre-derived materials.

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