What is mercury?

Mercury is a naturally occurring element that does not break down. It is a metal that is liquid at room temperature. It is extremely volatile, meaning it can easily be converted into a gas by evaporation. It is very heavy, highly conductive, and easily bonds with other metals to form useful amalgams. Mercury in its metallic form is often called "Quicksilver."

Where is it found?

Because of its unique properties, mercury is used in many different products including thermometers, thermostats, tilt switches, button batteries, and fluorescent lights. It is also used in paints, preservatives, chemical reagents, and pesticides.

In the environment, mercury is found in a mercuric sulfide ore called cinnabar. Mercury is also a trace level contaminant in fossil fuels.

How does it enter the environment?

Although mercury enters the environment from natural sources such as volcanoes, forest fires, and the weathering of rocks, much of the mercury that makes its way into the environment comes from anthropogenic (human-caused) sources.  Mercury can be released from coal-burning power plants, during the manufacture of mercury-containing products, metal mining, and the use of chemicals.  And humans don’t just put mercury in the air.  Mercury can also make its way from wastewater into our lakes, rivers, and oceans.

What are its hazards?

Mercury vapor is extremely toxic to humans. It is hazardous to inhale the vapors. Mercury vapor travels in the air and is deposited in oceans, lakes and rivers. 
Elemental mercury can be converted by bacteria in the water into an organic form of mercury called methylmercury. This organic compound is extremely soluble in water and it gets into the food chain poisoning fish and other animals. Over time, methylmercury bioaccumulates in larger fish, making them unsafe to eat.

How might I be exposed to mercury?  Will my health be affected?

Mercury is toxic to the nervous system, the brain and spinal cord, especially in the developing nervous system of a fetus or young child.
Overexposure symptoms begin with trembling hands and numbness or tingling in lips, tongue, fingers or toes. These effects can begin long after the exposure occurred. At higher exposures, walking could be affected, as well as vision, speech and hearing. In sufficient quantities, methylmercury can be fatal.
The greatest risk, however, is for fetuses and young children because their nervous systems are still developing. They are many times more sensitive to mercury than adults. Overexposure may cause a child to be late in beginning to walk and talk and may cause lifelong learning problems. Unborn children can be seriously affected even though there are no symptoms in the mothers.

What are the environmental effects?

Once mercury has made its way into a water body either through atmospheric deposition or by discharge from wastewater treatment plants, it is deposited in the sediment where microbes convert it to methylmercury.  From there, mercury has the capacity to build up in the tissues of organisms (a process called bioaccumulation) and to concentrate up the food chain (a process called biomagnification).  When people and animals eat a lot of fish from mercury-polluted waters, high methylmercury exposure can have many adverse effects.  For animals like loons, eagles, otters, mink, kingfishers and ospreys, the methylmercury buildup can result in reduced reproductive success, impaired growth and development, behavior abnormalities, and even death.

Does this mean I can't eat fish?

The benefits of eating fish outweighs the health risks as long as you follow guidelines about the kinds of fish you eat and how often you eat fish. 

Fish consumption advisories are put out by Wisconsin, Minnesota, Michigan, and Canada. Be sure to check what's safe to eat!

How should I handle mercury?

You should remember two important things: don't touch mercury and don't throw mercury in the garbage.

To transport your thermometers or mercury-containing products for recycling, double bag them using Zip-lock bags or contain them in a sealed plastic container. As a reminder, try to cushion the items to reduce the risk of spills.  

If You Have a Mercury Spill

• Keep people and pets away from the area.
• Use gloves, preferably rubber, to protect yourself.
• Do NOT use a vacuum or broom!
• Ventilate the area if possible.
• Scoop up the liquid with index cards and seal in a plastic bag or container.
• Take the mercury to one of our collection sites. Contact your local Health Department or the Wastewater Treatment Plant for more information.