Makarand writes "We all recognize vehicle tailpipe emissions to be a source of pollution. But what happens to the castoff rubber from your tires that have lost tread? No one knew where this rubbber was going until recently. Allison Draper, a professor of environmental chemistry at Bucknell University, is conducting research to end all guess work on this topic and with the hope of finding ways to make tires less polluting. She found for every kilometer a car travels, about 90 milligrams of tread wears off in particles ranging in size 10-75 microns.Toxins in the larger suspended particles leach out when exposed to water and the run off harms plant and animal life. These toxins are still being identified."