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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The Association of Natural Rubber Producing Countries (ANRPC) hosted a high-level delegation from PEFC International at its headquarters on 9 July 2026. The visiting team, led by Remco van Merm, engaged in strategic talks with ANRPC Secretary-General Dr Suttipong Angthong and his senior staff, marking a significant moment for inter-organisational collaboration.

The discussions provided a critical forum for exchanging perspectives on ongoing global initiatives and the shifting sustainability dynamics affecting the natural rubber sector. With mounting market pressures regarding environmental stewardship and social accountability, the conversation centred on harnessing joint efforts to fast-track the implementation of responsible practices throughout the entire production and distribution network.

Both organisations underscored the necessity of strengthened coordination among all industry participants to secure a robust and enduring future for natural rubber. The dialogue culminated in a shared pledge to deepen cooperation, with the goal of cultivating a more transparent and ecologically sound value chain. This mutual commitment is expected to deliver tangible benefits across the board, reinforcing the industry's capacity to meet emerging global standards.

Natural Rubber (NR) plantations developed under Project INROAD (Indian Natural Rubber Operations for Assisted Development) have reached 179,376 hectares across north-east India after the completion of planting for the 2025-26 financial year, bringing the initiative close to its original target of 200,000 hectares.

Launched in the 2021-22 financial year, the project has established new NR plantations across 113 districts in the region over the past five years. According to the project partners, this represents the country's largest expansion of natural rubber plantations achieved within such a period.

Project INROAD is funded by tyre manufacturers Apollo Tyres, CEAT, JK Tyre and MRF, and is implemented by the Rubber Board of India. It is described as the first initiative of its kind in which the Indian tyre industry directly supports the development of rubber plantations.

"Despite several operational challenges including Covid-induced disruptions in the beginning, nearly 90% of the ambitious target of 2 lakh hectares of new plantation has been achieved under Project INROAD during the last five years. Beyond plantation expansion, the project has also made significant progress in strengthening local nurseries and building grower capacities — a testament to the collaborative efforts of the tyre industry and the Rubber Board," said Mohan Kurian, chairman of Project INROAD.

The project has distributed a record 83m quality planting materials during the five-year period. It has focused on supporting resource-constrained communities in the designated states, particularly small and marginal farmers, most of whom own less than one hectare of land. More than 200,000 beneficiaries have been supported through the initiative, with the project aiming to improve livelihoods and promote socio-economic development.

Project INROAD has also expanded nursery infrastructure across the region. More than 200 nurseries are supplying high-yielding planting materials to growers, while new and improved rubber clones suited to the north-east's agro-climatic conditions are being distributed through the programme.

"With plantations reaching a critical stage, the next component of the project — development of supporting infrastructure such as model smokehouses and dissemination of improved practices among rubber growers — is progressing well under the INROAD Skilling and Production Efficiency Enhancement Drive (iSPEED) initiative," Kurian added.

Under the iSPEED initiative, infrastructure development is intended to improve the quality of rubber produced by farmers through value addition at source. The programme also plans to roll out large-scale digital and in-person training for growers, supported by newly developed training materials that are ready for release.

Epsilon Carbon, a leading global manufacturer of carbon black, speciality carbon and coal tar downstream products, has achieved a significant industry milestone by becoming the first carbon black manufacturer in India to secure certification from the Bureau of Indian Standards (BIS). This recognition, granted under the applicable Indian Standards, establishes a new benchmark for quality compliance within the domestic carbon black sector. The achievement distinguishes Epsilon Carbon as a pioneer in adhering to the nation's stringent regulatory framework for industrial materials.

The certification was awarded after an exhaustive evaluation of the company’s operational protocols, including its manufacturing workflows, quality management frameworks and product testing laboratories. This accomplishment is the culmination of prolonged and strategic investments aimed at refining process consistency, upgrading workforce expertise and standardising production methodologies. Consequently, the company is now exceptionally equipped to address the escalating requirements of tyre manufacturers, rubber product fabricators and various ancillary industries that demand rigorously vetted raw materials.

For Epsilon Carbon’s clientele, this official endorsement provides heightened confidence regarding product uniformity and regulatory adherence, a crucial factor as supply chains become increasingly scrutinised in both domestic and international markets. This development not only reinforces the company’s stature amid India’s transition towards a quality-centric industrial landscape but also advances its long-term vision of securing a global reputation as a premier supplier of high-performance carbon-based materials.

Gaurav Mathur, Chief Executive Officer, Epsilon Carbon, said, "This certification is an important milestone in our manufacturing journey. I congratulate our teams for the dedication that made this possible. It gives our customers greater confidence in our products, and it pushes us to keep raising the bar for what Indian manufacturing can deliver."