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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The Association of Natural Rubber Producing Countries (ANRPC) released its April 2026 report, highlighting rising prices despite lower production. Output fell 2.59 percent year-on-year due to the seasonal wintering period, dry weather across South and Southeast Asia and El Niño concerns. Brent crude surged to USD 117.29 per barrel, up 13.72 percent from March, driven by Middle East disruptions, which boosted centrifuged latex valuations.

Physical prices rose across all major grades. SMR-20 in Kuala Lumpur increased 4.61 percent to USD 2.13 per kilogramme, while STR-20 in Bangkok climbed 3.53 percent to USD 2.27. RSS-3 in Bangkok jumped 8.10 percent to USD 2.77, and RSS-4 in Kottayam rose 6.53 percent to USD 2.50. Centrifuged latex in Kuala Lumpur gained 12.47 percent to USD 1.93 per kilogramme. Futures markets remained firm, with the Shanghai Futures Exchange September 2026 contract averaging CNY 17,009 per tonne.

For 2026, global production is projected at 15.322 million tonnes, up 2.2 percent, with upward revisions for China and Malaysia. Consumption is forecast to grow 1.3 percent to 15.550 million tonnes, driven by electric vehicle production and recovery in rubber goods. In April alone, estimated output was 772,000 tonnes, while consumption reached 1,235,000 tonnes, a 2.3 percent annual rise.

Trade patterns diverged sharply. China’s imports fell 13.35 percent to 538,200 tonnes due to high inventories, while India’s imports surged 38.79 percent on strong manufacturing demand. Thailand’s exports contracted 4.28 percent to 378,000 tonnes, but Cambodia’s exports soared 106.49 percent. The Malaysian ringgit strengthened to near 3.96 against the US dollar, while the Thai baht stabilised around 3.07 after volatile trading.

The macroeconomic environment remained tense, with US-China trade friction, the Middle East conflict and the US Federal Reserve holding interest rates at 3.50 to 3.75 percent. The near-term outlook for natural rubber is cautiously positive but subject to heightened volatility.

The ANRPC reaffirmed its commitment to objective analysis for the sustainable development of the natural rubber sector. Member governments and stakeholders were encouraged to use the report’s findings for evidence-based policies.

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Indorama Advanced Oxides, a subsidiary of Indorama Corporation, has successfully restarted production at Huelva facility in Spain, achieving its first tonne of Titanium Dioxide (TiO₂) output. The plant, which has an annual capacity of 80,000 tonnes, represents the company’s strategic entry into the global titanium dioxide market. This milestone follows Indorama’s recent completion of the site acquisition from Venator P&A Spain.

The restart marks a crucial step in returning the facility to full operation after the acquisition, ensuring continued supply of the essential white pigment to customers across Europe and global markets. The Huelva team demonstrated strong collaboration and safe execution in resuming activities. This white pigment remains critical for the European paints, coatings and plastics industries.

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Synthos, recognised as Europe’s foremost synthetic rubber producer and a global leader in solution styrene butadiene rubber, has secured the EcoVadis Gold Medal once again. The company, also a top European manufacturer of expanded polystyrene, continues to rank among the world’s most sustainable businesses.

The 2026 assessment placed Synthos in the 97th percentile, with its highest marks received in labour rights, human rights, ethics and environmental stewardship. This achievement underscores steady advancement across multiple sustainability fronts and highlights a sustained dedication to responsible expansion and continuous innovation.

EcoVadis operates as a premier global evaluator of corporate sustainability, judging firms on environmental impact, social responsibility, ethical conduct and supply chain management using international standards. The Gold Medal’s annual renewal demands that Synthos consistently remain within the top three percent of all rated companies worldwide.

This recognition affirms that Synthos’ sustainability measures are both persistent and methodical. The company supports its long-range climate and circular economy goals through participation in the UN Global Compact and reporting aligned with ESRS and GRI standards. Synthos will keep leveraging EcoVadis feedback to refine future priorities and advance its ongoing sustainability journey.

Agata Gładysz-Stańczyk, CEO, Synthos, said, “Receiving the EcoVadis Gold Medal again confirms the importance of sustainability within our strategy and the commitment of Synthos teams across all locations. While we are proud of this achievement, we also see sustainability as a continuous journey. It is embedded in how we innovate, how we operate, and how we create value for our customers, employees, partners and communities. This recognition encourages us to continue strengthening our ambitions and driving further progress.”

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The Rubber Board Statistics Consultative Panel reviewed the performance of India’s natural rubber sector during its 29th meeting at the Rubber Board Headquarters in Kottayam. The panel, which includes representatives from small and large growers, producers’ societies, dealers, processors and tyre manufacturers, examined key indicators such as production, consumption, imports and exports. India remains the sixth-largest natural rubber producer globally.

Indian natural rubber production grew by 3.4 percent in the 2025-26 period, rising to 905,000 tonnes from 875,000 tonnes the previous year. Favourable weather across major rubber-growing regions increased tapping days and productivity. Board initiatives like rain guarding, self-tapping, scientific practices, skill programmes and disease control supported output, while Kerala’s Rubber Production Incentive Scheme also encouraged continued tapping.

Domestic natural rubber prices strengthened, renewing grower interest in tapping. Prices that rose sharply in 2024–25 showed relative stability in 2025–26, narrowing the gap with international rates. The trend continued into early 2026, with RSS-4 peaking at INR 262 per kg on 14 May. Meanwhile, total natural rubber demand rose 1.2 percent, though the auto tyre sector, accounting for nearly 64 percent of consumption, declined by 4.0 percent. The general rubber goods sector posted robust growth instead.

The panel noted a 16.7 percent decline in natural rubber imports, falling to 459,000 tonnes from 551,000 tonnes. However, imports of compounded rubber under HS Code 4005 increased significantly, reaching 349,000 tonnes from 245,000 tonnes in the previous year. Consumption of natural rubber rose 1.2 percent to 1,427,000 tonnes from 1,410,000 tonnes in 2024-25.

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