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."

 Watch a mercury webinar

Where is it found?

Mercury has unique properties that is useful in a variety of different products.
Common household items that contain mercury include:
  • Fluorescent bulbs
  • Button batteries
  • Thermometers
  • Thermostats
  • Dental amalgam
It is also used in paints, preservatives, chemical reagents, and pesticides (typically in older products).

mercury products

The Superior Wastewater Treatment Plant is a drop-off site for mercury-containing items, such as fluorescent bulbs, button cell batteries, old thermostats, and thermometers. This service is FREE for Douglas county residents. Do not dispose of items containing mercury into the trash. To view more drop-off bulb locations in Superior go


How does it enter the environment?

Mercury enters the environment from 3 natural sources (volcanoes, forest fires, and the weathering of rocks).
However, much of the mercury that makes its way into the environment comes from anthropogenic (human-caused) sources. Mercury is released from these sources:
  • Coal-burning power plants
  • Garbage or medical incinerators
  • Metal mining
  • Manufacture of mercury-containing products
  • Wastewater treatment plants (if mercury products are dumped in sewers)


Industrial Mercury Emissions in Wisconsin

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?

mad hatter
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!
fishing graphic

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.