Every year, billions of vehicles worldwide shed an estimated 6 million tons of tire fragments. These tiny flakes of plastic, generated by the wear and tear of normal driving, eventually accumulate in the soil, in rivers and lakes, and even in our food. Researchers in South China recently found tire-derived chemicals in most human urine samples.
Rubber is quite literally the sap of a rubber tree. Latex. They mix other materials in with it, but this is one instance where I don’t think the rubber is the issue.
It’s the fillers they put in the rubber; Nylon, Rayon, Polyester, etc.
Tires are about 25% steel fibers, another 30%ish filler materials, and Rubber (either synthetic or natural)