AN OVERLOOKED POLLUTION PROBLEM!

 

Tire Particles: The Overlooked Culprit of Microplastic Pollution

Every year, billions of vehicles around the globe shed an estimated 6 million tonnes of tire debris. These tiny particles, generated by the normal wear and tear of driving, gradually accumulate in our soils, rivers, lakes, and even in the food we consume. In a recent study from South China, tire-derived chemicals were detected in most human urine samples—a stark reminder of just how pervasive this pollution has become.

Tire particles are a major, yet often overlooked, contributor to the growing crisis of microplastic pollution. Globally, they account for 28 percent of the microplastics that enter the environment. Despite their scale, tire particles have largely evaded focused attention, often lumped together with other forms of microplastics. However, their unique characteristics make it essential to treat them as a distinct category of pollution, one that requires a specialized response.

Why We Need to Reclassify Tire Pollution

This recognition is urgently needed. In a recent international study, my colleagues and I concluded that categorizing tire particles as a separate pollution category would drive more focused research and inform targeted policies to reduce tire-related pollution. It would also raise awareness among the public, helping people better understand the scope of the problem and what they can do to help mitigate it.

At this very moment, delegates are meeting in South Korea to negotiate the first-ever global plastics pollution treaty. While this agreement promises to address many aspects of plastic pollution, tire particles have barely been mentioned. Given their significant contribution to global microplastic contamination, recognizing tire pollution as a distinct issue could lead to more effective solutions and greater public awareness.

The Complex Chemistry of Tire Particles

Tire particles are made from a complex mix of synthetic and natural rubbers, along with hundreds of chemical additives. This means the environmental impact of tire pollution can be far-reaching and sometimes unpredictable. For example, zinc oxide makes up about 0.7 percent of a tire's weight. While it's crucial for enhancing tire durability, zinc oxide is highly toxic to aquatic life, even in small quantities.

Another harmful chemical found in tires is 6PPD, which protects tires from cracking. When exposed to air and water, it transforms into 6PPD-quinone, a compound linked to massive fish die-offs in the U.S. Coho salmon, in particular, have been found to be especially vulnerable to the toxic effects of this chemical.

The Role of Vehicle Weight in Tire Pollution

Heavier vehicles—especially electric cars, which feature large, heavy batteries—tend to wear down tires faster, generating more microplastic pollution. Experts Nick Molden and Felix Leach have argued that vehicle weight is a critical factor in assessing a vehicle's environmental impact. They suggest implementing weight-based taxes on vehicles under a "polluter pays" principle, which would encourage automakers to design lighter vehicles and incentivize consumers to make more sustainable choices.

However, there is much more to understand. For instance, we still don’t know how far these tire particles spread or exactly where they accumulate in the environment. To fully assess their ecological impact, we need more detailed research into the behavior of tire additives, which species are most at risk, and how tire particles interact with the environment. Certain fish species, such as salmon, seem more sensitive to 6PPD-quinone than others, but more studies are needed to fully understand these effects.

The Need for Global Action and Regulation

While regulatory frameworks like the EU's upcoming Euro 7 emissions standard—which addresses vehicle emissions—offer a starting point for controlling tire pollution, further measures are necessary. Innovations in tire design, such as developing eco-friendly alternatives to zinc oxide and 6PPD, could significantly reduce environmental damage.

In addition, establishing a global panel of scientific and policy experts, similar to the IPCC (Intergovernmental Panel on Climate Change) or IPBES (Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services), could help coordinate research and regulatory efforts.

The most crucial step, however, is to formally classify tire particles as a distinct pollution category. Unlike conventional microplastics, tire particles break down into unique chemical compounds and present specific toxicological challenges that must be addressed.

With over 2 billion tires produced each year to support an ever-growing number of vehicles—many of which are getting heavier—the scale of the problem will only grow. If we fail to tackle tire pollution as its own distinct issue, the environmental consequences will continue to mount.

A Call for Change

Addressing tire pollution is not only about reducing environmental harm but also about paving the way for more sustainable transportation systems. Measures such as weight-based taxation for vehicles and innovations in tire materials could significantly reduce tire pollution and help build a greener future. The question isn't whether we can afford to act—it's whether we can afford not to.