Contaminants from mining processes in the Mantaro River Basin of Peru, including the lead smelter in La Oroya, have an impact on health and environmental quality. Results from exposure studies in La Oroya and a river basin monitoring program include lead, arsenic, cadmium and other metals in air, water and soil; SO2, NOx and O3 in air; biological contaminants in agricultural and drinking water; and biological measures of residents. The speakers will present results and discuss implications and policy impact.