Lead is an environmental pollutant highly toxic to human health. This chapter deals with the hazard index and environmental risk of lead accumulation in soil and agricultural products irrigated with water from the Mantaro River on the left bank of the Mantaro Valley in Jauja, the Junín region, Peru. The methodology applied was that recommended by the Environmental Protection Agency (EPA) and the Environmental Ministry of Peru (MINAM). Soil, water, corn and potato samples were analyzed and 35 people who are frequently exposed to lead contamination were interviewed including males and females from 4 to 83 years old. The results indicate that lead concentrations in corn and potato exceeded the maximum allowed levels by between 5 and 30 times. The hazard index between 0.1163 and 0.1186 corresponds to a low risk to the health of the population exposed. The environmental risk level for agricultural areas irrigated by the Mantaro River was high (0.67). Overall, the probability of damage to humans and the environment and at a socio-economic level due to contaminated food intake and lead accumulation in agricultural soils and groundwater was very high.