Mercury Exposure

Effects on Health


Limiting Mercury Exposure

Exposure in Minnesota

Political Campaign


Environmental mercury contamination in Minnesota originates from the burning of fossil fuels and household/industrial sources. Through these sources, mercury enters the air, the land, the lakes and rivers, and even unexpected places-like schools. For this North Star state, reducing mercury exposure has become a priority in three areas: fish consumption, school exposures, and occupational/environmental exposures. This section will look at these three areas of concern in Minnesota and report on what the state is doing to address the problems.

Mercury Exposure through Recreation and Consumption

“All fish tested in Minnesota have mercury…The amount [of mercury] depends on what the fish feed on, how old the fish are and to some degree the water they live” Patricia McCann, Environmental Scientist, Minnesota Department of Health

Minnesota is not only the land of 10,000 lakes, but also of over one million anglers.

Fishing is a popular recreational sport for many residents. According to the State’s Department of Natural Resources:

Minnesota has 2.3 million anglers (1.6 million licensed)

  • 3,800,000acres of fishing waters
  • 5, 493 fishable lakes
  • 15,000 miles of fishable streams
  • State Anglers generate 1.87 billion dollars in sports fish revenue
  • Most harvested fish are panfish, Walleye and Northern Pike

Although Minnesota fish and rivers are among the “cleanest” in the nation, they do contain a level of mercury that is of concern. For that reason Minnesota Department of Natural Resources (DNR), Minnesota Pollution Control Agency, and the Minnesota Department of Health issue advisories in order to limit exposure to mercury through fish consumption (especially fish caught as sport). Below is an example of the types of fish that are found in Minnesota lakes and rivers, and a general guideline from the DNR about which types of fish are safest to eat.

Minnesota Fish (from DNR website)


Northern Pike



Largemouth Bass

Smallmouth Bass



Bluegill (Sunfish)


Safe Fish Eating Guidelines

  • Eat smaller fish.
  • Eat more panfish (sunfish, crappies).
  • Eat fewer predator fish (walleyes, northern pike, lake trout).
  • Trim skin and fat, especially belly fat—PCBs build up in fish fat
  • Eat fewer fatty fish such as carp, catfish, and lake trout.

Mercury Exposure in Schools:

“The Minnesota Pollution Control Agency (MPCA) estimated that in 2001, Minnesota schools contained 4.7 pounds of mercury per school”

According to the Minnesota State Department of Health (MDH), mercury in schools can be found in chemistry and other science classrooms, school nurse offices, and in the school building itself through thermostats, electrical switches and florescent light bulbs. Even some gym floors made of polyurethane contain mercury. In order to help reduce the level of mercury exposure in schools, MDH established the Mercury Free Zone Program to:

  • Remove mercury from schools
  • Identify and encourage the use of mercury –free products
  • Educate students, teachers about dangers mercury.

As of May 2003, the program reports that 75 schools were assessed and over 500 pounds of mercury removed from Minnesota schools.

Minnesota Mercury Exposures FYI:

  • The Minnesota Medical Association, professional group for physicians, has supported legislation to ban the use of mercury filled thermometers. The group further passed a resolution within their own ranks to recommend “environmentally proper disposal of mercury-containing equipment.”

  • Mercury releases in Minnesota have dropped 68 percent in the past ten years, but 43 percent of Minnesota’s mercury emissions still come from coal-burning power.

  • In effort to find out the original sources of mercury contamination in fish and the state’s lakes and rivers, the Minnesota Department of Health is pushing for more mercury testing on the 640-acre U.S. Steel Duluth Workers Site. The site was the location of an operational steel mill from 1915-1979. Mercury was one of many of the contaminants found at the site, but the whole site was not tested for mercury. This site is of concern because it is located near water sources and mercury can travel long distances into the environment.

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