TOXIC chemicals released from car tyres as they wear down are threatening ocean life after washing into rivers and the sea, a new study has found.
The research has raised concerns about the impact of urban road runoff, especially in densely populated areas where concentrations of tyre chemicals are already high.
“This is a real warning sign,” said Henry Obanya, from the Institute of Marine Sciences at the University of Portsmouth.
“We need to start treating tyre pollution with the same urgency we apply to other plastic or oil pollution. These substances don’t just vanish – they travel through drainage systems and end up in habitats that are already under pressure.”
There are also concerns that the problem could grow with the global shift to electric vehicles. While these vehicles cut tailpipe emissions, they tend to be heavier, potentially accelerating tyre wear and increasing the release of these compounds unless tyre formulations change.
Significant air pollution also occurs from both tyre and brake wear. An estimated 1800-2700 premature deaths are attributed to air pollution in Scotland each year but the number of vehicles in the country is continuing to grow.
The total number of vehicles licensed in Scotland was 3.13 million in 2023, slightly higher than 2022, and 14% higher than in 2013. The number of private and light goods vehicles in 2023 was 2.7 million, slightly more than 2022, and 12% higher than 2013.
The scientists are now calling for tighter regulation of tyre ingredients, improved monitoring of road runoff and investment in the development of safer, less harmful alternatives.
They are also urging further research into the long-term and combined effects of tyre-related chemicals on marine life.
“Something as ordinary as driving a car can contribute to pollution that reaches far beyond the road, all the way to the sea floor and to the microscopic organisms that help keep our planet breathing,” said Obanya.
The study found that exposure to chemicals from tyres affects the growth of tiny marine algae called diatoms which, although tiny, support entire ocean ecosystems.
“This almost omnipresent and long-overlooked form of pollution impacts not only coastal ecosystems but aquatic environments more broadly and must be brought to the forefront of environmental regulation,” said Dr Fran Cabada-Blanco from Portsmouth’s Institute of Marine Sciences.
The research team examined three chemicals that are widely used in tyre manufacturing or formed as byproducts as tyres degrade: mercaptobenzothiazole (MBT), diphenylguanidine (DPG), and 6PPD-quinone.
All three are known to enter the environment via stormwater and urban runoff but their specific effects on marine plant life have been poorly understood until now.
The results showed all three chemicals suppressed diatom growth, with DPG and MBT proving especially harmful even at very low concentrations.
