Mercury is a naturally occurring element that is found in air, water, and soil. It exists in several forms: elemental or metallic mercury, inorganic mercury compounds, and organic mercury compounds.
Human activities, such as burning coal and using mercury to manufacture certain products, have increased the amount of mercury in many parts of the environment including the atmosphere and in lakes and streams. People and animals are exposed to mercury by eating organisms that live in places where microbes have converted some of the natural and human mercury to a more toxic form, methylmercury.
For more information about mercury and its effects on human health and the environment, visit EPA’s Mercury Web site.