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Mercury is one of the most prevalent toxic pollutants throughout our environment. It is both a natural toxin that comes from the Earth and a byproduct of industrial processes.

What is mercury, and why is it dangerous?

Mercury is a toxic metal that disrupts cell functioning and is therefore harmful to human health. It is a potent neurotoxin that is especially dangerous to the neurological development of infants and fetuses.

Sources of mercury exposure

Trace amounts of mercury are present in certain kinds of coal and can be released into the air by coal-fired power plants. According to the EPA, the largest sources of mercury emissions in the United States come from these sources:

  1. Coal-fired power plants: 51%
  2. Industrial/commercial/institutional boilers or process heaters: 15%
  3. Cement plants: 7% (Weise, 8-10-2010)


Mercury can also be found in fertilizer, and so runoff from farming operations is another source of mercury. It can also be released through mining operations and the runoff from abandoned mines. Yet according to the EPA, most mercury in water comes from particles in the atmosphere, created largely by coal-fired power plants, trash burning and concrete plants. (Weise, 8-20-2009) Airborne mercury can travel for thousands of miles before being sent back down to the earth via rain. It then mixes with bacteria in the environment to create methyl mercury (aka organic mercury), a more toxic form that is then bioaccumulated up the food chain. Hence it can be found in much of the food we eat, particularly fish and seafood. (See our sections mercury in fish and mercury in seafood.)

Safe levels of mercury exposure for kids

The U.S. Food and Drug Administration sets the ‘safe’ level of mercury exposure at 1 part per million. Anything beyond that and the agency has legal authority to remove a product from the market. Children absorb a higher dose of mercury for the same amount of exposure because of their smaller size. Yet “no amount of mercury is really safe,” says pediatrician and mercury expert Leo TraSande of the Mount Sinai School of Medicine in New York. He notes that children have suffered losses in IQ at 5.8 ug/l (Duncan, 2009), which can be achieved at levels below current safety standards.

People most vulnerable to mercury exposure

Children and pregnant or nursing women are especially vulnerable to mercury’s effects. Unfortunately, we’re all exposed to mercury through the air we breathe and the food we eat, and many women “have or average a body burden of methyl-mercury at or above the ‘acceptable’ standard.” (Shabecoff & Shabecoff, 2010, p. 43)

How long does it take to eliminate mercury from the body?

Most people will be able to expel mercury from their body within 30 to 40 days of exposure. However, individual mutations in certain genes can cause some people to eliminate it from their body more slowly than others. (Duncan, 2009)

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