Mercury is a metal that is found naturally in several forms. It is a shiny, silvery-white liquid used in thermometers. Mercury can evaporate and become a colorless, odorless vapor. It can combine with other material to form compounds that are dangerous to human health. 

How Is a Person Exposed to Mercury?
People can be exposed to mercury by breathing in air, eating food or drinking water contaminated with mercury. Mercury can also enter the body through the skin.

• Burning of waste
• Burning of coal in power plants
• Certain industrial processes

Mercury in the air eventually falls back to earth and builds up in oceans, lakes, rivers and streams. The fish in these waters absorb the mercury. When people eat these fish, they are exposed to mercury.

• Dental fillings
• Broken thermometers
• Broken fluorescent and high-intensity light bulbs

The Health Risks of Mercury Exposure
Mercury can damage many parts of the body, including the nervous system, the lungs, the kidneys, vision, and hearing. The seriousness of the risk depends upon how much mercury a person is exposed to. The risk is greater for fetuses and children than for adults.

Babies who are exposed to mercury while in the womb can suffer severe damage to the nervous system and may die. They may have brain damage, learning disabilities and hearing loss.

Eating Fish During Pregnancy
Eating too much fish containing mercury can be a health risk. The risk is especially serious for a fetus. For specific information, read the article Food Safety.

Mercury on the Job
Pregnant women should avoid working in jobs where they might be exposed to mercury liquid or vapors. If you have questions about exposure on the job, talk to your health care provider, preferably before you are pregnant.

Mercury in Dental Fillings
Some dental fillings contain mercury. In 1997, the U.S. Food and Drug Administration reviewed nearly 60 studies about mercury exposure and dental fillings. The FDA concluded that the health risk was low and that there was no reason to change dental practice. The World Health Organization agrees with this assessment. Meanwhile, dentists have begun using materials that do not contain mercury. Research on dental fillings continues.

The governments of Canada, Germany and New Zealand recommend that pregnant women avoid dental fillings that contain mercury.

Unless mercury fillings are broken or damaged, they should not be removed since removal may release mercury.

If you have concerns about dental fillings, speak to your dentist.

Discarding Broken Thermometers, Fluorescent Light Bulbs, and High-Intensity Light Bulbs
If you are pregnant, ask an adult who isn't pregnant to dispose of broken thermometers, fluorescent light bulbs, and high-intensity light bulbs. Do not let children handle these items. A vacuum cleaner should not be used to clean mercury spills. 

To avoid mercury spills, store these items in a way that prevents them from breaking. 

For specific information, see the recommendations provided by the U.S. Environmental Protection Agency.

September 2006