Soil contamination or
soil pollution is caused by the presence of
xenobiotic (human-made) chemicals or other alteration in the natural soil environment. It is typically caused by industrial activity, agricultural chemicals, or improper disposal of
waste. The most common chemicals involved are petroleum
hydrocarbons, polynuclear aromatic hydrocarbons (such as naphthalene and
benzo(a)pyrene),
solvents, pesticides,
lead, and other
heavy metals. Contamination is correlated with the degree of
industrialization and intensity of chemical usage.