a tire

Tires: The plastic polluter you never thought about

Because tires are made of natural rubber and plastic, it’s easy to miss just how much they contribute to pollution in our oceans.

Small bits of degraded plastic from tire wear pervade the environment, including the oceans, researchers are discovering.

Photograph by Hannah Whitaker, National Geographic

In 2014 biologist John Weinstein and his graduate students went looking for microplastics—the small bits of degraded plastic that researchers have discovered are spread throughout the environment.

The team was based at The Citadel military college in Charleston, South Carolina, where Weinstein is a professor. Working in a coastal city, they expected to find at least some evidence of microplastics, which are swept into the ocean. And sure enough, samples kept turning up.

Much of what they collected came from anticipated, identifiable sources, such as broken-down plastic bags. But more than half of the pieces were black, tubular, and microscopic, with no obvious origins.

“They’re elongated, almost like cigars,” says Weinstein. “It was a mystery.”

Weinstein and his students looked around

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