Mercury can escape into the environment when spilled mercury is poured down the drain or when items containing mercury are disposed in garbage cans or burned. If a mercury-containing device breaks and the spill is not cleaned up properly, the mercury will volatilize to form an odorless vapor, potentially reaching dangerous levels in indoor air. Mercury is also released from natural sources and through the combustion of fossil fuels and other industrial sources, such as steel-making furnaces and medical waste incinerators.
Once in the air, mercury can fall to the ground with rain and snow, landing on soils or water bodies. Methylmercury, an organic form of mercury, can accumulate up the food chain in lakes, streams and rivers, which results in high concentrations in the tissues of older and larger fish.
People are most frequently exposed to mercury through the consumption of contaminated fish. Human exposure can also occur by inhaling vapors from spilled mercury or leaking equipment. There have been cases of mercury exposures from accidental swallowing, but these cases are rare.
Mercury poses a health risk to everybody, but especially to young children and fetuses because they are still developing. Prolonged, low level exposure may cause learning disabilities by hurting the ability of children to think and read. Adults who have been exposed to high levels of mercury may experience trembling hands and numbness or tingling in their lips, tongues, fingers and toes. Acute mercury poisoning, especially through ingestion, can damage the brain, liver, kidneys and even cause death. Mercury can harm wildlife that eats contaminated fish, particularly bald eagles, loons and other fish-eating birds and mammals.
State officials have issued a statewide fish consumption advisory due to the concentration of mercury found in predator fish caught in Illinois waterways. The advisory cautions pregnant women, women of childbearing age, nursing mothers and young children to eat no more than one meal a week of predator fish. This includes all species of black bass (largemouth, smallmouth, and spotted), striped bass, white bass, hybrid striped bass, walleye, sauger, saugeye, flathead catfish, muskellunge and northern pike. More restrictive fish consumption advisories apply to some water bodies in Illinois.