Mercury is an element naturally occurring the earth's crust, including in deposits of coal. It can exist as an organic compound such as methylmercury, an inorganic compound, or in its elemental or metallic form. Methylmercury is the most common form of organic mercury and it is made when mercury combines with carbon and microscopic organisms convert it into methylmercury.

The most common way people in the U.S. are exposed to mercury is by eating fish containing methylmercury. Mercury gets into the air from a number of sources such as burning coal and oil as fuel. In the U.S., coal-burning power plants account for about half of manmade mercury emissions. Once in the air, mercury eventually settles into lakes and streams. Microorganisms in those water bodies can change the mercury into methylmercury, where it builds up in fish and shellfish.

Mercury is a neurotoxin and people exposed to high levels may experience health effects such as loss of peripheral vision; "pins and needles" feelings in the hands, feet, and around the mouth; loss of coordination; impairment of speech, hearing, or walking; or muscle weakness. Infants in the womb can be exposed to mercury when their mothers eat fish and shellfish containing methylmercury. This exposure can affect the unborn infants' growing brains and nervous systems. Children exposed to methylmercury in the womb can have impacts to their cognitive thinking, memory, attention, language, fine motor skills, and visual spatial skills.

To reduce mercury pollution and exposure to mercury, EPA regulates the amount of mercury released into the air and drinking water; discharged to wastewater; and disposed of in landfills. EPA is also working to:

• understand what levels of mercury pollution impact human health;
• measure and monitor mercury in the environment;
• clean up sites contaminated with mercury;
• provide guidance to reduce mercury exposures;
• develop and demonstrate technologies to prevent mercury air emissions;
• engage consumers to promote voluntary reductions in mercury use and release

To learn more about the health risks of mercury exposure and how to reduce those risks, click on the links below.