When the rains come, the water runs off the tailings into the rivers, making them turbid. Not surprising, says Mary Mueller, an environmental scientist in Colorado. Mueller points out that mining waste invariably contains heavy metals that are just as toxic as cyanide. Copper and sulfate concentrations exceeding one part per million can cause stomach and intestinal problems in humans and kill animals like horses. Lead and mercury can kill humans.
Local residents receive little in exchange for the toxic burden they are forced to bear.
Local mayors say that Newmont employs almost none of the local residents. Not one of the 1,800 people in Yanacancha Grande has been able to get a job with the company, according to local residents. And Francisco Llanos, the mayor of Combayo, says that a mere 10 people in his village of 4,936 people have jobs with Yanacocha. Those who are employed at Yanacocha toil under dangerous conditions. Yanacocha's Cotts says concerns about the mine's operational practices are unwarranted.