Soil is a complex mixture of minerals, organic material, water, and various life forms. In its original state, soil was an uncontaminated substance covering the earth. But humans have intentionally and accidentally poured harmful products onto it in some areas. The waste can hurt the soil and possibly human, plant, and animal health.

Soil pollution is defined as the presence of toxic chemicals (pollutants or contaminants) in soil, in high enough concentrations to pose a risk to human health and/or the ecosystem. In the case of contaminants which occur naturally in soil, even when their levels are not high enough to pose a risk, soil pollution is still said to occur if the levels of the contaminants in soil exceed the levels that should naturally be present.