Mercury Awareness
What is mercury?
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Mercury is a naturally occurring
metal. The metallic mercury is a shiny, silver-white, odorless liquid.
Metallic mercury is used to produce chlorine gas and caustic soda, and is
also used in thermometers, dental fillings, and batteries.
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Mercury combines with other
elements, such as chlorine, sulfur, or oxygen, to form inorganic mercury
compounds. Mercury salts are sometimes used in skin lightening creams and as
antiseptic creams and ointments.
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Mercury also combines with carbon
to make organic mercury compounds. The most common and most toxic one is
methylmercury, produced mainly by microscopic organisms in the water and
soil.
Why are we concerned about
mercury?
Mercury is a toxic persistent,
bioaccumulative pollutant that affects the nervous system. Methylmercury is a
chemical species that bioaccumulates in fish. Fish consumption advisories are in
effect for mercury in thousands of lakes and rivers,
including much of the Great Lakes ecosystem.
How does mercury enter the
environment?
Inorganic mercury enters the air from
mining ore deposits, burning coal and waste, and from manufacturing plants. It
enters the water or soil from natural deposits, disposal of wastes, and volcanic
activity.
Methylmercury may be formed in water
and soil by small organisms called bacteria. Methylmercury builds up in the
tissues of fish. Larger and older
fish tend to have the highest levels of mercury.
How do people get exposed to
mercury?
Eating fish or shellfish contaminated
with methylmercury. Breathing vapors in air from spills, incinerators, and
industries that burn mercury-containing fuels. Release of mercury from dental
work and medical treatments. Breathing contaminated workplace air or skin
contact during use in the workplace (dental, health services, chemical, and
other industries that use mercury). Practicing rituals that include mercury.
How does mercury affect children?
Brain damage, mental retardation,
incoordination, blindness, seizures, and inability to speak. Children poisoned
by mercury may develop problems of their nervous and digestive systems, and
kidney damage.
Sources of mercury in Wisconsin:
Wisconsin
DNR has estimated that 50% of the deposition in the state is from
in-state sources.
Source:
Wisconsin DNR, Decision on the Need for An Environmental Impact Assessment,
Draft, 2001
According to a report from National Wildlife Federation
the mercury content in the rain along the Illinois/Wisconsin border is as high as 56 times safe levels.
What are the current mercury
regulations?
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The EPA has set a limit of 2
parts of mercury per billion parts of drinking water (2 ppb).
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The Food and Drug Administration
(FDA) has set a maximum permissible level of 1 part of methylmercury in a
million parts of seafood (1 ppm).
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The Occupational Safety and
Health Administration (OSHA) has set limits of 0.1 milligram of organic
mercury per cubic meter of workplace air (0.1 mg/m3) and 0.05 mg/m3 of
metallic mercury vapor for 8-hour shifts and 40-hour work weeks.
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The EPA has set standards for mercury
in the Great Lakes and all the waters in the Great Lakes
basin, including Lake Michigan. These standards were developed during the
Great Lakes
Water Quality Initiative ("GLI") process and promulgated in
regulations. Each Great
Lakes state now is required to implement those regulations. The
GLI establishes two standards for mercury: one to protect people, and one to
protect wildlife.
The wildlife standard requires that lakes and streams contain no more than
1.3 parts
per trillion (ppt or ng/L) mercury in their water. The human health standard
sets a limit
of 1.8 ppt mercury in water.
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Wisconsin has adopted the GLI wildlife
standard for mercury, and has promulgated an even
lower standard for human health: 1.5 ppt. The Wisconsin standards apply to
every lake
and stream in the state and to Lakes Michigan and Superior.
Relevant website:
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