Car tires produce a quarter of all microplastics in the environment.

Billions of vehicles around the world throw away approximately 6 million tons of tire debris every year. These tiny flakes of plastic, created by the wear and tear of normal driving, eventually end up in the soil, in rivers and lakes, and even in our food. Scientists in South China recently found tire-derived chemicals in most human urine samples. (by Henry Obanya, The Conversation, more at phys.org)