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Tuesday, June 17, 2025

Micropollutants from Tire Waste: Similar to Microplastics, Prevalent Near Roadways, In Food: EV Tires Wear Faster


     When our tires wear out over time, that rubber is lost, particle by particle, on and near the roads they roll on. At least a couple of studies over the last few years have confirmed that micropollutants from tire waste have been contaminating vegetables in nearby farms. A 2024 study from Vienna, published in Frontiers of Environmental Science, confirmed that microparticles from car tires are getting into crops through a combination of atmospheric deposition, treated wastewater being used to irrigate, and sewage sludge being used as fertilizer. Fortunately, the concentration remains small, likely below the threshold to cause damage. Apparently, car tires contain hundreds of substances, some linked to nasty side effects at significant concentrations. For this reason, the use of rubber mulch, once considered a viable way to recycle tires, is being abandoned. Rubber mulch does not decompose like wood chip mulch. Thus, it also does not offer any nutrients to the soil like wood chip mulch does. In 2024, I was working for a local Health Department. One morning on the way to work, I got a call to go to the local recycling center, where trucks brought in tires that were dumped, and we loaded them into a semi. They were to be given or sold to a place that recycles them by shredding them into mulch. While we thought we were doing a public good deed, it now appears that is not the case.












     A May 2025 study from Switzerland, published in the Journal of Hazardous Materials, noted, according to Phys.org, that:

“…tires often "release additives such as antioxidants and vulcanizing agents" that can make their way to agriculture after dispersing through the air and being transported by runoff water. In addition to inhaling these chemicals, humans are exposed to them by ingesting contaminated food, researchers from the EPFL and the Swiss Federal Food Safety and Veterinary Office determined.”

They found that 31% of the samples contained traces of the compounds, including 6-PPD and 6-PPD-quinone, with no difference according to where the fruits and vegetables came from or whether they were organic.”





     The toxicity of the compounds to small mammals has been established. However, the effects on humans have not been established, and the dosages that would be dangerous have also not been established.  

When tires wear against road surfaces, they release additives such as antioxidants and vulcanizing agents (which give rubber more strength, elasticity, and durability). These particles, the toxicity of which is yet to be determined, disperse through the air, settle on the ground, and are transported in runoff water. Humans are exposed to them in two ways: by inhaling them and, as the EPFL-FSVO study shows, by ingesting them in contaminated food.”

     Highlights and the Abstract from the 2025 study are given below.






     One time when I was younger, I worked an 8-hour shift at a temporary job at a tire warehouse. The smell of the tires was strong, and after a while, I developed a headache. Although I’m not sure if I was exposed to anything dangerous, I was glad to get out of there.

     Phys.org cites a 2017 study that concluded that six million metric tons of these additives are released into the environment every year. These micropollutants have also been found in rural areas and in mountain lakes. Researchers say we don’t yet know whether we should seek to produce less-toxic alternatives or phase out the use of the materials. Road workers may be the most exposed to these toxins. Chinese researchers are currently studying the presence of these compounds in human blood and urine.

 

EVs are Heavy, Which Means They Produce Tire Waste Faster

     As we transition to more EVs, the problem of tire waste will intensify. This is because EVs are heavier due to battery weight, which makes tires wear faster due to more friction against the road, increasing the rate of localized contamination. The instant torque of EVs also contributes to faster tire wear. Driving habits can slightly reduce the rate of EV tire wear. According to an article in the Morning Review:

Manufacturers are actively working on developing new tire technologies that can withstand the unique demands of electric vehicles. Advances in materials and design aim to improve the durability of EV tires, ensuring they last longer despite the additional stresses imposed by the vehicle’s weight and torque.”


References:

 

New study makes concerning discovery about farms where food is grown: 'A critical step in understanding the potential risks'. Doric Sam. The Cool Down. May 19, 2025. New study makes concerning discovery about farms where food is grown: 'A critical step in understanding the potential risks'

Electric Cars Destroy Tires—Here’s Why It Happens So Fast. Alexander Clark. Morning Overview. June 8, 2025. Electric Cars Destroy Tires—Here’s Why It Happens So Fast

New study raises concerns after finding levels of car tire materials in vegetables: 'That's not where they belong'. Jenny Allison. The Cool Down. June 15, 2024. New study raises concerns after finding levels of car tire materials in vegetables: 'That's not where they belong'

Assessment of tire-derived additives and their metabolites into fruit, root and leafy vegetables and evaluation of dietary intake in Swiss adults. Florian Breider, Thibault Masset, Kelyan Prud’homme, and Beat J. Brüschweiler. Journal of Hazardous Materials. Volume 494, 15 August 2025. Assessment of tire-derived additives and their metabolites into fruit, root and leafy vegetables and evaluation of dietary intake in Swiss adults - ScienceDirect

Uptake of tire-derived compounds in leafy vegetables and implications for human dietary exposure. Anya Sherman, Luzian Elijah Hämmerle, Evyatar Ben Mordechay, Benny Chefetz, Thorsten Hüffer, and Thilo Hofmann. Front. Environ. Sci., 27 May 2024. Sec. Toxicology, Pollution and the Environment. Volume 12 - 2024 | https://doi.org/10.3389/fenvs.2024.1384506.

Gardener seeks advice with remediating landscaping mistake left by previous homeowner: 'It makes me cringe and want to cry'. Kelsey Kovner. The Cool Down. June 7, 2024. Gardener seeks advice with remediating landscaping mistake left by previous homeowner: 'It makes me cringe and want to cry'

Tire additives found deposited on fruits and vegetables. Sandrine Perroud, Ecole Polytechnique Federale de Lausanne. Phys.org. May 6, 2025. Tire additives found deposited on fruits and vegetables

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