What Do You Know About Mercury?
Mercury is a very dense, naturally-occurring element.
Mercury conducts electricity and expands and contracts uniformly with changing temperature.
Mercury easily amalgamates with other metals, such as gold, silver, zinc and cadmium. Dental amalgam is an alloy that is made of 43 to 54% mercury combined with a percentage of silver, tin, zinc and copper.
Mercury forms very useful compounds with other elements. Some of these mercury compounds are mercuric oxide, mercuric sulphide, mercuric chloride, and mercuric nitrate. Mercuric nitrate was used historically in the felt making process for hats. Mercury poisoning was so prevalent amongst hatters in the industry that it served as an inspiration for Lewis Carroll's character "The Mad Hatter" in his story, "Alice in Wonderland."
Mercury can be found in various types of mercury-containing equipment, such as thermometers, barometers, manometers and switches.
The Forms/Risks of Mercury
Mercury has three forms: elemental (liquid mercury), inorganic mercury and organic mercury (methylmercury).
Elemental mercury is the most common form. It is a metallic, silvery liquid ( also referred to as quicksilver) that is processed from an ore called cinnabar. It readily breaks into droplets and easily vaporizes at room temperature into an odorless, colorless vapor that can easily be inhaled.
RISK: It easily crosses blood/brain and placental barriers and can enter breast milk. It is a potent neurotoxin that impacts the central nervous system. Some of the neurological effects are: tremors, mood swings, irritability, excessive shyness, insomnia, loss of coordination, slurred speech, and "pins and needles sensation". Very high exposures can cause kidney effects, respiratory failure, and death.
Inorganic mercury is usually white, except for cinnabar, which is red. Inorganic mercury can enter the body through mouth and skin from products such a disinfectants and fungicides. Inorganic mercury compounds are frequently found in school science labs.
RISK: Inorganic mercury is the least toxic of the three forms of mercury. It can damage the GI tract, as well as the kidneys and nervous system. High exposures can lead to skin rashes, dermatitis, mood swings, memory loss, mental disturbance, and muscle weakness.
Organic mercury, methylmercury is most commonly found in the environment. It is converted from its inorganic form by a biological bacterial process. It bioaccumulates in the environment and is most commonly found in fish. Oral ingestion of fish is the most common route of exposure of mercury to humans.
RISK:Methylmercury crosses blood/brain and placental barriers, which can damage the central nervous system and causes birth defects, neurological problems and developmental delays. Fetuses are the most vulnerable to methylmercury's toxic effects because studies have shown that chord blood levels are twice as concentrated as maternal blood levels for mercury. Chronic exposure to methylmercury can cause an impairment in vision, speech, walking, hearing, lack of coordination and cause a "pins and needles" sensation. Extreme exposures can lead to death.
The Mercury Cycle in the Environment
A large proportion of the mercury that is released into the atmosphere comes from coal-fired electric power plants. A fair amount of mercury that is released into the atmosphere also comes from naturally-occurring sources, such as volcanoes. Mercury is also released into the atmosphere by municipal and medical waste incinerators.
Mercury in the atmosphere comes back down to the land and waterways in the form of dry deposition and wet deposition in rain and snow. Mercury also gets into waterways from industrial and sewerage discharges and from municipal landfill leachate. Through bacterial processes, inorganic mercury is converted into organic mercury, or methylmercury. Methylmercury bioaccumulates up the food chain, from small aquatic organisms, to small fish to larger fish, to wildlife and humans.
One hundred and forty-eight lakes, reservoirs and ponds have been tested by the New York State Department of Environmental Conservation (DEC) since 2001. Sixty-three of those lakes are now under the New York State's Department of Health fish consumption advisories, with a high concentration of these located in the Adirondack and Catskill Mountains regions of the state. The fish species with the highest mean mercury concentrations are, not surprisingly, the larger predatory fish, such as walleye, northern pike, chain pickerel and smallmouth and largemouth bass.
Mercury in the environment is also impacting our wildlife. Predominantly fish-eating birds (eagles and loons) and mammals (minks and otters) are showing effects, such as behavioral and reproductive changes, from mercury poisoning. Even insect-eating animals from forest ecosystems, such as song birds and bats, are accumulating high levels of mercury, which is an indication that deposition of mercury in terrestrial environments is also a problem.
DEC has passed many regulations recently to regulate mercury air emissions, mercury-containing products and dental amalgam. More information on mercury management in New York State can be found by visiting DEC's web site on Mercury Management.