Tires have long had a negative impact on the environment. However, it’s worse than expected, a new study claims.

Ever since the automotive age began, tires have been a major source of pollution. There are hundreds of millions of them lying in dumps and landfills, often serving as breeding grounds for mosquitoes and other pests. And, when they catch fire – which is not uncommon – old tires can create taxes plumes of smoke.

Now, a new study warns that tires may pose a serious problem even while still in use. Researchers working with the San Francisco Estuary Institute and the 5 Gyres Institute believe that microscopic-size particles of plastic found in the compounds used in today’s tires, are being sloughed off during normal wear-and-tire and then washed off roads and into streams and rivers where they can flow into lakes, estuaries, bays and oceans.

Of the estimated 7 trillion pieces of microplastics that wash into San Francisco Bay – the focus of the new study – tire-generated particles appear to be 300 times greater than what comes from other sources, including fibers from clothing going through the wash, the microbeads in beauty products and other waste.

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“I’m so used to thinking of the toxics that come from urban runoff and not the actual physical particles from something like tire dust,” said Mark Gold, who heads the California Ocean Protection Council, told the Los Angeles Times in an extensive story examining the problem. “But the sheer number of particles … the scope and scale of this problem makes you realize that this is something that’s definitely worth looking at a great deal more seriously.”

An estimated 8 million tons of plastic waste flow into the oceans each year, much of that winding up in garbage patches like this one in the Pacific.

Plastic ocean waste has become a major concern. A Texas-sized patch floats around the Pacific Ocean, and it is just one of many in global oceans. But microplastics are raising increasing concerns for marine biologists and other scientists – including those who focus on the health of our food supply.

Most plastics can survive the elements almost indefinitely but, as they enter waterways, they can be torn and eroded into ever smaller pieces. Scientists have found beaches where this waste is being transformed into new types of minerals, in some cases coating rocks and jetties. Studies are underway to see if marine life, notably mussels and other mollusks, might wind up consuming some of the plastic-based materials.

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It’s already known that microplastics are winding up in clams, shrimp, fish, even some of the sea’s largest life forms, such as sharks and whales. Where such animals are consumed by humans, we wind up ingesting those particles.

“A recent UC Davis study sampled seafood sold at local markets in Half Moon Bay, California, and found that one-quarter of the fish and one-third of the shellfish contained plastic debris,” the LA Times said in its report. “A survey comparing 150 tap-water samples from five continents found synthetic microfibers in almost every sample — 94% in the United States.”

Studies have yet to determine what the long-term impact will be. Part of the concern is the variety of microplastics winding up in our waterways. In the case of tires, that can a complex mix of vulcanized rubber as well as the many petrochemical substances manufacturers mix in to help add strength and traction and to improve a vehicle’s fuel economy.

Researchers estimated there are 414 million pieces of plastic waste washed up on the remote Keeling Islands. Photo courtest: Silke Stuckenbrock

Dealing with plastic pollution, large and small, has become a major issue. Solutions range from the often mocked move by California and some other jurisdictions to ban plastic straws to finding new materials and compounds that naturally degrade.

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But researchers face a serious challenger when it comes to tires. The new study, and others, could be seen to encourage more use of public transportation, but it’s unlikely that can address but a minute fraction of the tire problem. The question is whether tire manufacturers can come up with a way to either reduce waste or, at least, use materials that can completely degrade over time, not just break down into ever-smaller particles that may never go away.