The dangers of end-of-life tyres to people and the environment

Garden decor, fences, and flower beds made from worn car tires have long become a common sight. Many perceive this as an affordable design option, without even suspecting that end-of-life tires are harmful to the environment and human health. 

A logical conclusion suggests itself – if they are dangerous and this kind of decor must be abandoned, then after use, they should simply be thrown into a landfill with the rest of the garbage. In reality, this is also prohibited. Tires are not biodegradable waste, meaning they cannot be buried in the soil. As a result, not only do landfill volumes increase, but a threat to human health also arises. Scientists at the Institute for Freshwater Ecology in Germany identified 2,456 chemical substances in tire rubber, 144 of which leach into the environment. In Europe, the disposal of old tires is handled responsibly, and the recycling rate exceeds 90%. Meanwhile, in Ukraine, only 15% of end-of-life tires are recycled, despite 250,000 tons of tires being discarded annually.

To understand the scale of this problem, it is worth starting with the composition of the tire itself. 

Why tires cannot be thrown in a landfill

Car tires are a high-tech product. Formulas are constantly being improved, with new components and synthetic compounds added. The mixture used to make tires contains over 120 different chemical substances and components. Among them, the following pose a threat:

• Carbon black (or soot). The International Agency for Research on Cancer (IARC) classifies carbon black as "possibly carcinogenic to humans" (Group 2B). Soot particles generate reactive oxygen species — unstable molecules that damage DNA and cell membranes. This oxidative stress can lead to mutations over time.
• Synthetic rubber. Its main components in tires are styrene and butadiene. Styrene has neurotoxic properties, while butadiene is recognized as a proven human carcinogen linked to the development of leukemia and lymphoma. Aromatic oils in the rubber may contain polycyclic aromatic hydrocarbons (PAHs) in concentrations up to 700 mg/kg.
• Oils and plasticizers with high toxicity. Highly aromatic oils, widely used in the tire industry, contain high concentrations of PAHs, which have proven carcinogenicity. Since 2010, their use has been banned in the EU under the REACH regulation (1907/2007).
• Silicic acid (silicon dioxide). A single tire contains about 9.65% silicon dioxide by mass, which is gradually released, causing air pollution.
• Sulfur. Makes up about 1.28% of the tire's mass and is used in the vulcanization process. When the tire decomposes, sulfur reacts with moisture and metal components, contributing to soil acidification and the formation of soluble sulfates.
• Textile and steel cord. When the tire degrades and the steel cord is exposed, levels of manganese and iron in groundwater increase noticeably, and the concentration of aluminum and zinc in the soil rises. 

For decades, manufacturers have been striving to create a material that is cheaper to produce, more durable, and more wear-resistant. However, even such a material gradually degrades under the influence of natural factors, breaking down into the various substances and chemical compounds from which it is made. 

Similarly, end-of-life car tires discarded in landfills or used for amateur landscaping are exposed to environmental factors – sunlight, temperature fluctuations, and rain. Under their influence, the components in the tires begin to gradually break down, polluting the environment. The study "Pollution Effect of Painted End-of-Life Tires on Water Resources" (IJPSAT journal, Vol. 39, No. 2, July 2023) detects toluene, aromatic compounds, carboxylic acids, aniline, benzene, phenolic compounds, hydrocarbons, copper, nickel, and zinc in tire leachate. Moreover, the longer the tires are left outdoors, the greater the damage to nature and humans. 

Burning them is also not advisable. When burned, in addition to soot, toxic substances are released that pollute the air and settle on plants, soil, and water bodies. The tire dump fire in Winchester in 1983 lasted for 9 months and contaminated 2,800 m² of soil with pyrolysis oil. Groundwater pollution from such events persists for years and requires active remediation. 

Harm of used tires to human health

Worn tires represent a long-term source of environmental and sanitary risks. The thing is, the harm from old car tires manifests gradually. Under the influence of high summer temperatures and UV rays, volatile compounds dangerous to human health are released from the rubber:

• allergens;
• carcinogens – nitrosamines and benzo[a]pyrene provoke oncological diseases;
• dioxins and furans – highly toxic substances that affect the liver and immune system;
• formaldehydes and phenols – they are part of the resin and glue formulas used in tire manufacturing.

As they break down, all components are released into the environment, and if people live nearby or children play there, they inhale these substances, which poison the body and can cause serious diseases – from asthma to oncology. In IARC scientific publications, the standardized mortality ratio (SMR) or relative risk (RR) of cardiovascular or respiratory pathologies among tire manufacturing workers is 20-150% higher than the average population rates. In production, this is due to systematic contact with high concentrations of substances in enclosed spaces — hence the statistics. In open landfills, concentrations are lower, but the impact on health and the environment does not stop. 

From this, it can be concluded that end-of-life car tires are indeed dangerous to humans. But perhaps they can be stored where there are no large crowds of people? Tires are also harmful to the environment, being one of the most serious sources of natural pollution.

What harm do old car tires cause to the environment?

To fully answer this question, let's answer a second one: are tires toxic? In fact – yes. Car tires are classified as Class IV hazardous waste. In the international waste catalog, they are assigned the code 16 01 03. They are classified as "low-hazard waste".

Despite having a Class IV hazard rating ("low hazard"), end-of-life tires cause harm to both the environment and humans. The mass accumulation of worn rubber and non-compliance with storage conditions turn them into a source of toxins and harmful substances.

Among the main problems, it is also worth noting the fact that worn tires take a very long time to decompose in the natural environment. This process takes over 100 years, and throughout this period, the tires remain a source of pollution. Therefore, rubber waste disposal requires a technological approach and must be carried out in compliance with environmental safety rules. If this is not done, the harm caused by worn car tires to nature will be very significant.

In the process of degradation under the influence of natural factors, tires pollute the soil and increase its acidity. During decomposition, they release heavy metals (cadmium, lead, zinc), which seep into groundwater and spread to water bodies and wells, poisoning the water. The soil becomes unsuitable for the growth of healthy plants and the life of beneficial organisms. As a result, large areas turn into contaminated zones that will take hundreds of years to clean up. The risks and consequences for nature are serious and will affect more than one generation of people.

What to do when you need to get rid of old tires without creating a danger to the environment? The solution to this problem is the responsible transfer of tires for recycling.

Greenwin will help with proper tire disposal

Car tire recycling is one of the most practical and safe ways to solve the disposal issue. Rubber crumb for stadium surfaces, fuel, or new parts can be made from tires. At the same time, it is important to use technologies that make the recycling process safe for the environment.

Greenwin is engaged in the disposal of end-of-life car tires in compliance with environmental standards. Our recycling center uses modern technologies and methods that reduce the negative impact on the environment. In our work, we adhere to the principle – "waste should bring benefits." The company uses end-of-life car tires to create new resources that can be used for the benefit of society without risks to the environment.