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

1.        Thompson. Identification of vehicle tyre rubber in roadway dust. Am Ind Hyg Assoc 27, 488–495 (1966).

2.        Lassen, C., Hansen, S.F., Magnusson, K., Norén, F., Hartmann, N.I.B., Jensen, P.R., Nielsen, T.G., Brinch, A. Microplastics - Occurence, effects and sources of releases to the environment in Denmark. (Danish EPA, 2015).

3.        Boucher, J. & Friot, D. Primary microplastics in the oceans: A global evaluation of sources. (2017). doi:10.2305/IUCN.CH.2017.01.en

4.        Kole, P. J., Löhr, A. J., Belleghem, F. G. A. J. Van & Ragas, A. M. J. Wear and tear of tyres : A stealthy source of microplastics in the environment. Int. J. Environ. Res. Public Health 14, 1265 (2017).

5.        Kolomijeca, A., Parrot, J., Khan, H., Shires, K., Clarence, S, Sullivan, C., Chibwe, L., Sinton, D., Rochman, C. Increased Temperature and Turbulence Alter the Effects of Leachates from Tyre Particles on Fathead Minnow (Pimephales promelas). Environ. Sci. Technol. 54, 1750–1759 (2020).

6.        Unice, K. M., Panko, J.M.., Chu, J. & Kreider, M. L. Measurement of airborne concentrations of tyre and road wear particles in urban and rural areas of France, Japan, and the United States. Atmos. Environ. 72, 192–199 (2013).

7.        Kreider, M. L., Unice, K. M. & Panko, J. M. Human health risk assessment of Tyre and Road Wear Particles (TRWP) in air. Hum. Ecol. Risk Assess. 0, 1–19 (2019).

8.        Unice, K. M. et al. Characterizing export of land-based microplastics to the estuary - Part I: Application of integrated geospatial microplastic transport models to assess tyre and road wear particles in the Seine watershed. Sci. Total Environ. 646, 1639–1649 (2019).

9.        Unice, K. M. et al. Characterizing export of land-based microplastics to the estuary - Part II: Sensitivity analysis of an integrated geospatial microplastic transport modeling assessment of tyre and road wear particles. Sci. Total Environ. 646, 1650–1659 (2019).

10.      Wik, A. & Dave, G. Occurrence and effects of tyre wear particles in the environment - A critical review and an initial risk assessment. Environ. Pollut. 157, 1–11 (2009).

11.      Redondo-Hasselerharm, P. E., de Ruijter, V. N., Mintenig, S. M., Verschoor, A. & Koelmans, A. A. Ingestion and chronic effects of car tyre tread particles on freshwater benthic macroinvertebrates. Environ. Sci. Technol. acs.est.8b05035 (2018). doi:10.1021/acs.est.8b05035

12.      Khan, F. R., Halle, L. L. & Palmqvist, A. Acute and long-term toxicity of micronized car tyre wear particles to Hyalella azteca. Aquat. Toxicol. 213, 105216 (2019).

13.      Halle, L. L., Palmqvist, A., Kampmann, K. & Khan, F. R. Ecotoxicology of micronized tyre rubber : Past , present and future considerations. Sci. Total Environ. 135694 (2019). doi:10.1016/j.scitotenv.2019.135694

14.      LaPlaca, S. B. & van den Hurk, P. Toxicological effects of micronized tyre crumb rubber on mummichog (Fundulus heteroclitus) and fathead minnow (Pimephales promelas). Ecotoxicology (2020). doi:10.1007/s10646-020-02210-7

15.      Kellough, R. M. The effects of scrap automobile tyres in water. (1991).

16.      Day, K. E., Holtze, K. E., Metcalfe-Smith, J. L., Bishop, C. T. & Dutka, B. J. Toxicity of leachate from automobile tyres to aquatic biota. Chemosphere 27, 665–675 (1993).

17.      Abernethy, S. The acute lethality to rainbow trout of water contaminated by an automobile tyre. (1994).

18.      Hartwell, S. I., Jordahl, D. M., Dawson, C. E. O. & Ives, A. S. Toxicity of scrap tyre leachates in estuarine salinities: Are tyres acceptable for artificial reefs? Trans. Am. Fish. Soc. 127, 796–806 (1998).

19.      Hartwell, S. I., Jordahl, D. M. & Dawson, C. E. O. The effect of salinity on tyre leachate toxicity. Water. Air. Soil Pollut. 121, 119–131 (2000).

20.      Gunasekara, A. S., Donovan, J. A. & Xing, B. Ground discarded tyres remove naphthalene, toluene, and mercury from water. Chemosphere 41, 1155–1160 (2000).

21.      Edil, T. B., Park, J. K. & Kim, J. Y. Effectiveness of scrap tyre chips as sorptive drainage material. J. Environ. Eng. 130, 824–831 (2004).

22.      Lisi, R. D., Park, J. K. & Stier, J. C. Mitigating nutrient leaching with a sub-surface drainage layer of granulated tyres. Waste Manag. 24, 831–839 (2004).

23.      Aydilek, A. H., Madden, E. T. & Demirkan, M. M. Field evaluation of a leachate collection system constructed with scrap tyres. J. Geotech. Geoenvironmental Eng. 132, 990–1000 (2006).

24.      Alamo-Nole, L. A., Perales-Perez, O. & Roman, F. R. Use of recycled tyres crumb rubber to remove organic contaminants from aqueous and gaseous phases. Desalin. Water Treat. 49, 296–306 (2012).

25.      Alamo-Nole, L. A., Perales-Perez, O. & Roman-Velazquez, F. R. Sorption study of toluene and xylene in aqueous solutions by recycled tyres crumb rubber. J. Hazard. Mater. 185, 107–111 (2011).

26.      Parker-Jurd, F. N. F. Napper, I. E. Abbott, G. D. Hann, S. Wright, S. L. Thompson, R. C. Investigating the sources and pathways of synthetic fibre and vehicle tyre wear contamination into the marine environment (project code ME5435). (2019).

27.      Kumata, H., Yamada, J., Masuda, K., Takada, H., Sato, Y., Sakurai, T., Fujiwara, K. Benzothiazolamines as tyre-derived molecular markers: Sorptive behavior in street runoff and application to source apportioning. Environ. Sci. Technol. 36, 702–708 (2002).

28.      Klöckner, P., Reemtsmp, T., Eisentraut, P., Braun, U., Ruhl, A.S., Wagner, S. Tyre and road wear particles in road environment – Quantification and assessment of particle dynamics by Zn determination after density separation. Chemosphere 222, 714–721 (2019).

In pursuit of its strategic vision, ‘Michelin in Motion 2030’, Michelin is expanding into high-value adjacent markets, including the development of its Polymer Composite Solutions. A key step in this growth is the acquisition of Flexitallic, a global leader in sealing solutions based in Houston, Texas. This move is set to substantially enhance Michelin’s sealing portfolio and extend its market access, particularly within the aftermarket sector.

Flexitallic serves critical industries such as energy and chemicals, providing high-performance gaskets, sheet products and specialty filler materials known for exceptional reliability and resistance in extreme, safety-critical environments. The company, which operates 17 facilities worldwide and employs about 1,200 people, reported sales of approximately USD 220 million in 2025.

The acquisition is a strong strategic fit, uniting two global organisations with a shared commitment to innovation and quality, thereby creating significant synergies for future growth. The transaction, for an undisclosed amount, will be fully financed from Michelin’s available cash. Subject to standard regulatory approvals and closing adjustments, it is anticipated to be finalised in the first half of 2026.

Birla Carbon has inaugurated a dedicated production line at its Trecate, Italy facility, specifically engineered for the finishing and packaging of its Continua Sustainable Carbonaceous Material (SCM). This industry-leading circular material is produced from end-of-life tyres, and the new line enables its manufacture in large, consistent volumes. This expansion directly strengthens long-term supply security for the company’s worldwide customer base.

The Continua SCM range, including the 8000 series for tyres, rubber goods and plastics, provides a scalable sustainable solution. It allows customers to increase recycled content while gaining functional benefits such as blending flexibility and lower homologation costs. Importantly, it delivers assured regulatory compliance and consistent quality, supporting industries in their transition toward enhanced product circularity and reduced environmental impact.

John Loudermilk, President and CEO, Birla Carbon, said, “This is a pivotal moment for Birla Carbon. Continua SCM represents the most consistent, high-quality, circular material in the carbon black industry today and replaces a portion of carbon black in most rubber and non-rubber applications. It also reflects cross-industry collaboration for sustainability, with raw material sourced from our partner Circtec’s newly launched tire pyrolysis facility in the Netherlands and finished and packed at our state of-the-art processing line in Trecate. The launch of this line is a key milestone in our ambition to put back into industry 300,000 tonnes of end-of-life tyres annually by 2030, contributing to our aspiration to achieve net zero carbon emissions by 2050.”

John Davidson, Chief Sales, Marketing and Sustainability Officer, Birla Carbon, said, “The launch of the Continua SCM processing line in Trecate ramps up the availability of our circular product portfolio for customers globally. Continua SCM enables our customers to increase the use of sustainable materials in their products while maintaining the performance standards they expect. This expansion reinforces our commitment to supporting customer sustainability goals at scale.”

German chemical group WACKER has announced significant price increases for a wide range of silicone products, effective from 1 February 2026. These adjustments, which will see prices rise by up to 25 percent or even higher in specific instances, will be applied across existing customer contracts as necessary. The decision is a direct response to unprecedented surges in raw material costs, most notably for the precious metal platinum, a critical catalyst used in the production of addition-curing silicone products and crosslinking silicone release agents.

According to Tom Koini, Head of Silicones, the extreme market dynamics have made this step unavoidable, as internal efficiency measures can no longer absorb the cost pressure. Platinum prices on international commodity exchanges have more than doubled since the beginning of the previous year. WACKER states that the price adjustments are essential to maintain its high standards of product quality, customer service and technical support moving forward. The increases will specifically affect addition-curing silicone rubber grades, silicone resins, silanes and silicone-based release coatings.

The company’s Silicones division, a global leader with a portfolio of over 2,800 specialised products, serves key industries including automotive, pharmaceuticals, medical technology, electrical engineering and energy transmission. The portfolio encompasses silicone fluids, elastomers, resins, sealants, silanes and release coatings, all designed to enhance the performance and value of end products. In 2024, this division accounted for approximately 49 percent of the Group’s total sales.

ARLANXEO, a leading performance elastomers company, has officially opened its new Therban hydrogenated nitrile butadiene rubber (HNBR) production facility in Changzhou, China. This advanced plant, dedicated to producing the Therban brand, is designed to meet rising demand across vital industries including new energy, automotive, aerospace and next-generation battery technologies, where materials must endure extreme operational conditions.

Strategically positioned within ARLANXEO’s existing Changzhou complex, which also houses an EPDM plant and a Regional Technology Centre, the new installation strengthens the company’s integrated approach from innovation to manufacturing. It forms a crucial part of a global production network that includes sites in United States and Germany, establishing Changzhou as a central hub for the Asia-Pacific region.

The facility boasts an annual design capacity of 5,000 tonnes, with the first phase of 2,500 tonnes having successfully commenced operations in October 2025. It was completed with an exemplary safety record, achieving over 1.1 million incident-free work hours throughout its construction and commissioning, which was concluded within 13 months.

Engineered for high efficiency and environmental responsibility, the plant incorporates state-of-the-art finishing technology for consistent product quality. A key feature is an advanced thermal oxidation system that recovers energy and cuts carbon emissions in core processes by approximately 80 percent compared to traditional methods. Furthermore, the facility employs a closed-loop design that eliminates routine process wastewater discharge, supporting ARLANXEO’s commitment to reducing greenhouse gas emissions.

The inauguration was marked by a ceremony attended by senior leadership from ARLANXEO and its shareholder committee, alongside representatives from key customers, local authorities and community partners. This expansion significantly enhances ARLANXEO’s ability to supply reliable, high-performance elastomer solutions to its regional customer base.

Dr Faisal Al Faqeer, ARLANXEO Shareholders’ Committee Chairman and Aramco Senior Vice President of In-Kingdom Liquids to Chemicals Development, said, “China is important in supporting Aramco’s downstream growth. ARLANXEO’s new Therban® HNBR plant is the most recent demonstration of Aramco’s downstream expansion strategy of portfolio diversification and integration, underscoring our confidence in China’s innovation and manufacturing strength. We look forward to deepening our cooperation and further contributing to China’s high-quality and sustainable growth.”

Stephan van Santbrink, CEO, ARLANXEO, said, “Today’s inauguration marks an important milestone for ARLANXEO and a strong demonstration of our long-term commitment to China. We sincerely thank the Changzhou government, Aramco and all stakeholders for their trust and continued support. With the new HNBR plant now fully operational, we are further integrating our local production and R&D capabilities to strengthen the resilience of our global supply network. By delivering locally produced, high-quality rubber products, we will continue to collaborate with our customers and accelerate application innovation, creating greater economic and social value across our value chain.”