Tracking Tire Plastics—and Chemicals—From Road to Plate

July 16, 2024 | Source: Civil Eats | by Virginia Gewin

In the last few years, vehicle tires have emerged as a shockingly prolific producer of microplastics. It probably shouldn’t come as a surprise. Each year, roughly 3 billion new tires are made, consisting of synthetic rubber, which is a plastic polymer, as well as natural rubber, metal, and other materials. And each year, about 800 million of them become waste. As tires wear down—from contact with the road or the friction of the brakes—they shed chemical-laden particles, and those chemicals, it turns out, can find their way into crops.

Tire-derived microplastics are a growing source of plastic pollution and a target of the United Nations International Plastic Treaty negotiations. Further, concern is growing about the hundreds of chemicals, up to 15 percent of the weight of the tire, that are shed into the environment via tire microplastics. “It is the additives that are the toxic compounds,” says Thilo Hofmann, an environmental scientist at the University of Vienna.

While scientists agree that tire particles contribute significantly to microplastic emissions in the environment, the numbers are difficult to quantify. Recent studies have found tire particles made up to 30 percent of microplastics in Germany, roughly 54 percent in China, 61 to 79 percent in Sweden, and a whopping 94 percent in Switzerland.