Yup, a lot of products use iron oxide(rust) and it's derivatives. To produce it in the U.S. you need do inside in a facility, contain the chemical run off, and can only produce a maximum amount per EPA regulations. In China, they just spray the metal outdoors and let the chemicals leech into the ground.

It's easy enough to bribe a local tribesman on a reservation to look the other way. And who investigates? Usually, tribes hate police on the reserve.