The Environmental Quality Institute


Coal-fired power plantsMercury is a naturally occurring element that exists as elemental mercury, inorganic mercury compounds, and organic mercury compounds. It is found in air, water, soil, and rocks such as coal. When coal is burned, mercury can be released into the environment; in fact, coal-fired power plants are the largest anthropogenic source of mercury emissions to the air in the United States , accounting for 40% of all mercury emissions. The remaining mercury can be released through the burning of hazardous waste, production of chlorine, breaking of mercury products, and spilling of mercury. Mercury in the air eventually works its way into water where certain microorganisms change it into a highly toxic form called methylmercury. Methylmercury can build up over time in fish, shellfish, and animals that eat fish. The levels of methylmercury in fish and shellfish depend on several factors, including what they eat, how long they live, and their trophic status.

Mercury Exposure

The consumption of fish is the primary route of methylmercury exposure in humans. In 2004, the EPA and FDA released a joint advisory on the consumption of fish. Individuals can consult the EPA's fish advisories for further information on both state and federal advisories, and the FDA's food safety guide for specific information on different fish species. In addition to supplying consumption guidelines, the EPA has suggested a human health consumption limit of 0.3 mg/kg of methylmercury in fish tissue.

Mercury exposure in humans is a concern because it has many negative health effects. At high levels, mercury can damage the brain, heart, kidneys, lungs, and immune system of individuals at any age. Methylmercury poisoning can also cause impairment of peripheral vision; disturbances in sensations; lack of coordination; impairment of speech, hearing, and walking; and muscle weakness. Research has shown that the average person's fish consumptions does not cause a health concern, but it has also been shown that fetuses, infants, and young children are far more susceptible to methylmercury exposure. High levels of methylmercury in the bloodstream of this sensitive population may harm the developing nervous system and impair neurological development. Children who were exposed to methylmercury in the womb may have adverse effects on cognitive thinking, memory, attention, language, and fine motor and visual spatial skills.

Testing Mercury Levels

EQI formed a partnership with the national environmental organizations, Greenpeace and the Sierra Club, to give individuals an opportunity to test their mercury levels. The nationwide study examined human exposure to mercury as measured by hair mercury levels. Hair samples were analyzed in the laboratory using a Cold Vapor technique. EQI used the information from this project to perform statistical analyses to determine associations between mercury levels and variables such as age, gender, geographic location, fish consumption habits, and number of dental amalgams. The interim results for this project were released in October 2004.

Testing fish samples for mercury EQI also tested fish samples for mercury content in association with the Waterkeepers organization. That project tested different fish species from all over the nation in an attempt to find correlations between fish species, geographic location, and mercury content.

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