Researchers from the University of Plymouth are calling for better environmental regulations on tyre-related pollutants, following a study of the damage tyre wear particles cause to marine life.
As exhaust emissions from road traffic slowly fall, more attention is being paid to non exhaust emissions, that is from brake wear, tyre wear and road surface wear.
Not only are all three caused by traffic, subsequent traffic resuspends the particles, creating a vicious circle of poor air quality, until they are eventually washed away.
The team from Plymouth explored what happens to tyre-wear particles after this, when they are washed into rivers and oceans, introducing pollutants into aquatic environments.
Specifically, they looked at how certain chemicals affect a species of microscopic algae called Phaeodactylum tricornutum. These algae, known as diatoms, are essential to marine ecosystems because they help capture CO2 from the atmosphere and form the base of the ocean food web.
While these chemicals have already been shown to harm fish and other aquatic animals, scientists still don’t fully understand their effects on diatoms. This is concerning because if diatoms are harmed, it could disrupt the entire ocean food web and reduce the ocean’s ability to regulate climate through carbon storage.
The study focussed on three chemicals which are either added to tyres during manufacturing or are formed when tyre materials break down: 6PPD-quinone (6PPD-Q), diphenylguanidine (DPG), and mercaptobenzothiazole (MBT).
The researchers exposed the algae to different concentrations of the three chemicals in a controlled lab environment. They found that all three reduced the growth of these algae in a way that depended on how much of the chemical was present.
DPG and MBT were found to be the most harmful even at very low concentrations. Notably, the levels that caused harm in the lab are similar to or even lower than concentrations already found in polluted waters.
Higher concentrations of 6PPD-Q was required to damage the algae but, as the researchers point out, it is widespread and persistent and can accumulate in organisms over time, possibly leading to long-term genetic and cellular damage.
The researchers suggest that the rise of heavier electric vehicles may worsen the issue by increasing tyre wear. To address this, they call for stricter regulation of tyre ingredients, better monitoring of road runoff and the development of safer alternatives.
Dr Fran Cabada-Blanco from the University’s Institute of Marine Sciences said: ‘Diatoms play a disproportionately important role in coastal food webs and the global carbon cycle. Our findings highlight the urgent need to better understand how these widespread pollutants affect marine life. 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.’
Henry Obanya, also from the Institute of Marine Sciences and member of the Revolution Plastics Institute at the University of Portsmouth. said: ‘This is a real warning sign. 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.
‘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.’
The full research can be read here.
Photo: Nickolas Nikolic
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