Researchers discover disturbing evidence of ‘cocktail of chemicals’ lurking in our cars: ‘One of the most toxic substances known’

Cars are a major source of pollution — most notably, we hear a lot about tailpipe pollution from gas-powered vehicles. However, research indicates that a shocking amount of pollution comes from one surprising source found in gas-powered and electric vehicles alike: the tires.

What is happening?

Researchers looking into unusually high mortality rates in salmon were surprised to find that the cause of the salmon die-off was 6PPD, a chemical used in rubber tires. When that chemical meets the road and is exposed to ground-level ozone, it creates a slew of other toxic chemicals, including 6PPD-quinone, aka. 6PPD-q, which is then washed into waterways when it rains.

Why is it concerning?

“We have known that tires contribute significantly to environmental pollution, but only recently have we begun to uncover the extent of that,” said Cassandra Johannessen, a researcher at Montreal’s Concordia University. “[6PPD-q is] one of the most toxic substances known, and it seems to be everywhere in the world.”


6PPD-q is not the only toxic chemical found in tire dust (the microparticles released by the friction between the tires and roads), either. A recent report from researchers at Imperial College London found that “There is emerging evidence that [tire] wear particles and other particulate matter may contribute to a range of negative health impacts including heart, lung, developmental, reproductive, and cancer outcomes.”

“You’ve got a chemical cocktail in these tires that no one really understands and is kept highly confidential by the tire manufacturers,” said Nick Molden, the CEO of British firm Emissions Analytics to YaleEnvironment360. “We struggle to think of another consumer product that is so prevalent in the world, and used by virtually everyone, where there is so little known of what is in them.”

What is being done about it?

Fortunately, there is now some movement on this previously underrated health hazard. Legal nonprofit Earthjustice recently filed a notice to sue tire manufacturers for violating the Endangered Species Act by using 6PPD. A coalition of Native American tribes has also called on the EPA to ban the use of the chemical.

And movement is already being made on the regulatory front — the California Environmental Protection Agency passed a rule requiring tire makers to declare an alternative to 6PPD-q by 2024.

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