What is Mercury?
Mercury (chemical symbol Hg) is the only common metal that is liquid at ordinary room temperatures. It is also a good electrical conductor, so it is used in many electrical switches and devices.
There are three forms of mercury: elemental mercury, inorganic mercury, and methyl mercury. Normally, mercury is released to the environment in elemental or inorganic forms. Methyl mercury is often found in fish; it bio-accumulates through the food chain.
Methyl mercury is an organic compound, which results from biological processes. This form of mercury can affect the nervous system in people of all ages. Also, methyl mercury can have a variety of adverse effects on developing fetuses.
What Health Effects are Associated with Ingesting Mercury?
Higher exposures to mercury can cause health effects such as tremors, inability to walk, convulsions, and even death. Lower exposures to mercury can cause more subtle - yet still serious - damage to the senses and the brain.
Mercury exposure has also been linked to a variety of abnormalities in developing fetuses, such as delayed onset of walking and talking, delays and deficits in learning abilities, and reduced neurological tests scores.
How can I tell if I am affected by mercury?
Symptoms of mercury poisoning usually begin with numbness and tingling in the fingers and toes, irritability, tremors. High-level, long-term exposure can lead to memory loss, vision loss, hearing loss, psychosis, birth defects, and death. All forms of mercury affect the central nervous system. High levels of elemental, inorganic, or organic mercury can permanently damage the brain, kidneys, and developing fetuses. Organic forms of mercury, which are found in the edible parts of fish, are the most toxic.
Can Mercury be Removed from Fish?
Generally no; mercury is found throughout the fish tissue. So, normally responsible cleaning and cooking techniques, while effective in reducing other contaminants, will not reduce the amount of mercury in a meal of fish.
How does Mercury get into the Food Chain?
Mercury, a naturally occurring element, is mined by humans and used in numerous household products, dental fillings, and industrial processes. It is also a trace element in fossil fuels (primarily coal). Although there are many potential sources, the greatest anthropogenic source of mercury in water appears to be emissions from coal fired electric plants. Natural sources of mercury contamination include volcanic activity.
Mercury released into the air can travel long distances and then be deposited into streams and lakes through atmospheric deposition (fall-out), making it nearly impossible to pinpoint sources of contamination. Mercury is also released into water and air by some industrial processes, waste incineration, and improper disposal of mercury-containing products.
Can we get rid of it?
Unfortunately, you can't "get rid of" mercury - it does not degrade. Soil, sludge, and other solid waste contaminated with mercury can be removed and disposed of elsewhere, such as in an approved hazardous waste landfill, but it will never be gone.
In order to reduce the risk of further mercury contamination, mercury use is being phased out of certain products, like batteries and children's light-up shoes. Industrial permit limits are becoming more stringent, and better control technology is being developed. As a result, mercury discharges into streams and lakes have been greatly reduced in the past few decades.
What Can I (We) Do?
You can do a "mercury survey" of your home or workplace and look for sources of mercury. You can make certain that those sources are properly managed so that mercury does not reach the environment or affect people in your home or workplace.
More information on mercury:
U.S. EPA - Mercury Information
U.S. FDA - Mercury Levels in Commercial Fish and Shellfish
U.S. FDA - Consumer Advisory
NCDENR - Mercury Sources in North Carolina |
