The Yanacocha Gold Mine began operations in the department of Cajamarca in 1993. Yanacocha, the largest gold mine in South America, comprised of six open pit mines, four leach pads and three processing facilities. In June 2000, a contractor to Minera Yanacocha spilled 151 kg of elemental mercury along a 41 km stretch of road between the mine site and the town of Choropampa. A number of local people, unaware of the nature of the chemical, were exposed and subsequently experienced adverse health effects. In July 2000, CAO oversaw an independent investigation into the spill, which found there were significant discrepancies in the company’s waste management and emergency procedures. In December 2000, the Frente de Defensa de Choropampa lodged a complaint with CAO on behalf of citizens affected by the mercury spill. The complaint alleged that the adverse impacts being experienced by those exposed to the mercury had worsened and that Yanacocha failed to honor its commitments to affected individuals.