Mercury is a naturally-occurring element that is liquid at room temperature. The liquid form of mercury is also referred to as metallic mercury, elemental mercury, and quicksilver. Mercury can be used to measure temperature and pressure, conduct electricity, and act as a biocide and a catalyst. Because of these useful properties, it is used in many household and industrial products.

In the wrong place, mercury is a pollutant. 2/3s of atmospheric mercury comes from coal-burning power plants, incinerators and other sources. About 1/3 of atmospheric mercury comes from natural sources, such as volcanoes and forest fires.

To learn more about pollution visit the Minnesota Pollution Control Agency website.

Why is it a problem?
Mercury is a neurotoxin and an airborne pollutant. Mercury exposure can occur from skin contact with spilled mercury, swallowing liquid mercury, inhaling airborne mercury, or eating fish that contain mercury. The toxicity of mercury has long been known. During the 1800s, the hat industry used mercury to give a metallic sheen to felt hats. Over time, the hat makers suffered neurological damage from inhaling mercury vapors, resulting in shaking and slurred speech. This gave rise to the term "mad as a hatter." The liquid (metallic) form is relatively harmless for short-term skin contact, more serious if ingested, and very serious if inhaled.

If mercury gets into the blood stream, it can cause neurological damage, affecting brain, spinal cord, kidneys and liver. This also pertains to fetuses.Mercury has many different forms, including liquid (metallic), airborne and organic (methylmercury). Mercury gets into the air when coal, oil, wood, or natural gas is burned or when garbage is incinerated. Rain or snow then washes this airborne mercury into bodies of water where the small concentrations are magnified by the aquatic food chain.

Devices found in the home contain liquid mercury. If humans or animals ingest liquid mercury, their bodies are not able to absorb or accumulate liquid mercury to any significant extent. However, spilled liquid mercury can become a problem when allowed to volatilize indoors into airborne mercury. An indoor spill of mercury can be serious. After a mercury spill, a significant amount of mercury vapor can build up in indoor air at room temperature. It can be dangerous to breathe these mercury vapors. Because of this, it's important to clean even a few drops of spilled mercury as soon as possible. It is also important never to heat up liquid mercury. When heated, mercury evaporates rapidly, causing large quantities of mercury to go into the air.

People are mainly exposed to mercury by eating fish that have accumulated the organic form of mercury, methylmercury. After rain and snow washes airborne mercury into lakes and streams, bacteria converts some of the mercury into methylmercury. Plankton, small animals and plants living in water, take up methylmercury from water and sediment. Fish, in turn, eat plankton, thereby accumulating methylmercury in their tissues. Fish absorb most of the methylmercury to which they are exposed. The older and larger the fish, the more methylmercury builds up in its tissues. The human body accumulates mercury in the same way.