Well "illegal gold mining" is banned kind of by definition. Admittedly it seems Peru and places aren't enforcing the laws as well as they could but it's kind of a different category of problem. And I'm not sure you can regard the US as responsible for making gold valuable as it was for thousands of years before the US existed.
I'm just comparing people who intentionally make a choice to poison themselves and so many animals around them for tiny shiny bits opposed to unintentional deaths during medical research. I don't blame US in any way.
