I was with the "understanding" that iron contaminants on vehicles came from two sources : rail dust when the vehicle is transported from the manufacturing facility to a dealer or distribution center OR from cast iron or steel alloy brake rotors as they are being used-and-abused (and the way people drive these days in any major metro area or even in rural mountainous areas, it is "used-and-abused"). Am I "wrong" about that? I cannot believe it is industrial fallout, UNLESS you live near a foundry or steel mill.