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Road traffic is a major source of water pollution

Although heavy road traffic is most often associated with air pollution, a new study led by the University of Toronto Scarborough has found that it is also a major contributor to water pollution. Chemicals commonly used in vehicle fluids, tires, and paints were found to be much higher in rivers located nearby roads with heavy traffic.

“We found a strong relationship between traffic and the concentration of these chemicals,” said study lead author Tife Awonaike, a recent PhD graduate in Physical and Environmental Sciences. “These roads also appear to be a major source of a surprisingly wide array of contaminants.”

The researchers collected a series of samples from Mimico Creek and Little Rouge Creek and found 35 different contaminants from chemicals used in oils, lubricants, windshield de-icing fluids, tires, paints, coatings, and vehicle furniture. After being emitted onto road surfaces, they get washed into nearby streams when it rains, most often together with road dust.

Such contaminants are highly damaging for aquatic ecosystems. For instance, organophosphate esters (commonly added to materials as flame retardants) or triphenyl phosphate (a kind of organophosphate used in electronic equipment, vehicle interiors, and upholstery) have been linked to neurotoxicity in fish.

“Urban waters in general are not in good shape. They’re really a soup of a whole slew of contaminants,” said study co-author Frank Wania, an environmental chemist at the University of Toronto Scarborough. “Let’s put it this way — places like the Mimico Creek are not very healthy bodies of water, and it would be very difficult for a healthy aquatic ecosystem to exist there.”  

According to Professor Wania and his colleagues, in order to solve these problems, switching to electric vehicles will not be enough. Although some of the contaminants are related to burning fossil fuels, others found in paints, tire particles, coatings, or de-icing fluids are also used in electric vehicles.

These chemicals used to manufacture vehicles should be controlled by regulatory agencies and governments. Regular street sweeping could also help by collecting road dust before it gets flushed away in the nearby waters. Moreover, on an individual level, there are some activities that could help too.

“Regular maintenance of your vehicle is important. You can make sure to fix a leaky car or flaking paint chips,” said Dr. Awonaike. “You can also raise awareness about this issue. We don’t want these contaminants ending up in our water where they can do quite a bit of damage to aquatic ecosystems.”

The study is published in the journal Environmental Research Letters.

By Andrei Ionescu, Staff Writer

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