Tire microplastics
Firstly, what is microplastics? Simply put, microplastics refer to plastic particles with a diameter of less than 5 millimeters, which typically come from the degradation of plastic products, industrial production, and other activities. When we drive a car, the wear material generated by the friction between the tires and the ground contains a large amount of microplastics. These tiny particles will eventually flow into soil and water bodies, causing an impact on the environment.
Firstly, let’s take a look at biobased materials. Traditional tire manufacturing mainly relies on petroleum based materials such as synthetic rubber. And bio based materials are extracted from plants, such as natural rubber, bio polyester, etc. These materials not only have good performance, but also reduce dependence on oil to a certain extent.
More importantly, bio based materials have relatively good degradability and can decompose faster in natural environments, reducing the formation of microplastics.
In addition to bio based materials, tire manufacturers are also developing new composite materials aimed at improving tire wear resistance and reducing microplastic emissions caused by wear. For example, some manufacturers are experimenting with combining high-strength fibers with rubber to make tires more durable during use. This innovation not only helps to extend the service life of tires, but also serves as an effective means to reduce microplastic pollution.
Environmentally friendly tires involve not only material innovation, but also improvements in production processes. Many companies are shifting towards more environmentally friendly production processes, such as using solvent-free coatings and adhesives, to reduce environmental pollution during the production process. Although these measures may seem small, their impact when implemented in large-scale production cannot be underestimated.
1/4 of microplastic pollution comes from car tires
Billions of cars travel globally every year, releasing approximately 6 million tons of tire debris due to normal wear and tear. These tiny plastic particles eventually settle in soil, rivers, lakes, and even enter our food chain. Recently, researchers in southern China have found chemicals from tires in most human urine samples.
Tire particles are an important source of microplastic pollution, but they are often overlooked. They account for 28% of the total amount of microplastics entering the environment worldwide. Despite the severity of the problem, tire particles are rarely regarded as an independent source of pollution and are often confused with other microplastics. In fact, the specificity of these particles requires different processing methods.
We must treat tire particles as an independent category of pollution. In our recent international study, the team found that this classification helps to drive more focused research and provide guidance for policies to reduce tire pollution. At the same time, it can also help the public understand the scale of the problem and take action.
The hidden dangers of hundreds of chemical additives
Tire particles are made by mixing synthetic rubber and natural rubber, and contain hundreds of chemical additives. These additives lead to unexpected and far-reaching pollution consequences. For example, zinc oxide accounts for about 0.7% of tire weight. This ingredient can enhance tire durability, but it is highly toxic to fish and other aquatic organisms, and even trace amounts can damage ecosystems.
Another harmful additive is a chemical called 6PPD, which can prevent tire cracking. But after exposure to air and water, 6PPD is converted to 6PPD quinone, a compound that has been shown to be associated with large-scale fish mortality events in the United States.
Heavy vehicles bring more pollution
Research has shown that heavier vehicles, including electric vehicles equipped with heavy batteries, accelerate tire wear and produce more microplastic particles. Automotive industry experts Nick Molden and Felix Leach suggest implementing a tax policy based on vehicle weight for manufacturers, with the principle of ‘polluter pays’. This not only promotes the design of lightweight vehicles, but also encourages consumers to choose more environmentally friendly modes of transportation.
We still have many questions that urgently need to be answered. For example, how far can these tire particles spread? Where do they accumulate? To comprehensively assess its ecological impact, we need more detailed information, such as which tire additives are most toxic, their behavior patterns in the environment, and which species are most affected (such as certain salmon being more sensitive to 6PPD quinone).
In the long run, developing standardized methods for measuring tire particles is the key to effective regulation.
Global action is imperative
The existing regulatory framework, such as the upcoming implementation of the EU’s Euro 7 emission standard, while providing a starting point for controlling tire emissions, is still far from sufficient.
Innovations in tire design, such as replacing zinc oxide and 6PPD with environmentally friendly materials, can significantly reduce environmental hazards. In addition, establishing global scientific and policy expert groups similar to the Climate Science IPCC or Biodiversity IPBES can further coordinate research and regulatory work.
It is crucial that we classify tire particles as independent sources of pollution. Compared to traditional microplastics, the behavior, decomposition process, and toxicity characteristics of tire particles in the environment are different.
More than 2 billion tires are produced globally each year to meet the increasing and heavier demand for vehicles. If this problem is not addressed and resolved, the environmental burden will continue to increase.
