TOXICOLOGY
 |
| AGENCY FOR TOXIC SUBSTANCES AND DISEASE REGISTRY
This fact sheet answers the most frequently asked health questions about mercury. For more information, you may call 404-639-6000. This fact sheet is one in a series of summaries about hazardous substances and their health effects. This information is important because this substance may harm you. The effects of exposure to any hazardous substance depend on the dose, the duration, how you are exposed, personal traits and habits, and whether other chemicals are present. SUMMARY Exposure to mercury occurs from breathing contaminated air, ingesting contaminated water and food, and having dental and medical treatments. Mercury, at high levels, may damage the brain, kidneys, and developing fetus. This chemical has been found in at least 667 of 1,416 National Priorities List sites identified by the Environmental Protection Agency.
WHAT IS MERCURY? Mercury is a naturally occurring metal which has several forms. The metallic mercury is a shiny, silver-white, odorless liquid. If heated, it is a colorless, odorless gas. Mercury combines with other elements, such as chlorine, sulfur, or oxygen, to form inorganic mercury compounds or "salts." Most inorganic mercury compounds are white powders or crystals. Mercury also combines with carbon to make organic mercury compounds. The most common organic mercury compound is methylmercury. Methylmercury is produced mainly by small organisms in the water and soil, but more mercury in the environment can increase the levels of methylmercury that these small organisms make. Metallic mercury is used to produce chlorine gas and caustic soda and also in thermometers, dental fillings, and batteries. Mercury salts are used in skin-lightening creams and as antiseptic creams and ointments. WHAT HAPPENS TO MERCURY WHEN IT ENTERS THE ENVIRONMENT? Inorganic mercury (metallic mercury and inorganic mercury compounds) 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 the use of mercury-containing fungicides. Methylmercury may be formed in water and soil by small organisms called bacteria. Methylmercury builds up in the tissues of fish and other organisms. Its levels in tissues increase as we go up the food chain. HOW MIGHT I BE 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 during dental 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) Exposure to above-background levels in air, soil, and water near hazardous waste sites. HOW CAN MERCURY AFFECT MY HEALTH? The nervous system is very sensitive to all forms of mercury, although some forms are more harmful than others because of how the body handles them. Breathing metal vapors, or breathing or ingesting methylmercury causes the most harm because more mercury in these forms reaches the brain. Exposure to high levels of metallic, inorganic, or organic mercury can permanently damage the brain, kidneys, and developing fetus. Effects on brain functioning may result in irritability, shyness, tremors, changes in vision or hearing, and memory problems. Short-term exposure to high levels of metallic mercury vapors may also cause other effects including lung damage, nausea, vomiting, diarrhea, increases in blood pressure or heart rate, skin rashes, and eye irritation. Exposure to high levels of inorganic mercury salts can cause kidney damage, nervous system effects, nausea, and diarrhea. In some repeated poisoning incidents, people who ate contaminated fish or seed grains with high levels of methyl-mercury developed permanent damage to the brain, kidneys, and growing fetuses. Exposure to methylmercury is more dangerous for young children than for adults, because more of it passes into children's brains where it interferes with normal development. HOW LIKELY IS MERCURY TO CAUSE CANCER? The Department of Health and Human Services, the International Agency for Research on Cancer, and the Environmental Protection Agency (EPA) have not classified mercury as to its human carcinogenicity because of a lack of data from studies on people and laboratory animals. IS THERE A MEDICAL TEST TO SHOW WHETHER I'VE BEEN EXPOSED TO MERCURY? Tests are available to measure mercury levels in the body. Blood or urine samples are used to test for exposure to metallic mercury and to inorganic forms of mercury. Measurement of mercury in whole blood or in scalp hair is used to measure exposure to methylmercury. Your doctor can take samples and send them to a testing laboratory. HAS THE FEDERAL GOVERNMENT MADE RECOMMENDATIONS TO PROTECT HUMAN HEALTH? The EPA has set a limit of 2 parts of mercury per billion parts of drinking water (2 ppb). The EPA requires that discharges or spills of 1 pound or more of mercury be reported. 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). The Occupational Safety and Health Administration (OSHA) has set a limit of 1 milligram of mercury per 10 cubic meters of workplace air (1 mg/10 m3) that should not be exceeded during any part of the workday. GLOSSARY Carcinogenicity: Ability to cause cancer. Ingesting: Taking food or drink into your body. Milligram (mg): One thousandth of a gram. PPB: Parts per billion. PPM: Parts per million. REFERENCES
Agency for Toxic Substances and Disease Registry (ATSDR).
Agency for Toxic Substances and Disease Registry (ATSDR).
WHERE CAN I GET MORE INFORMATION? ATSDR can tell you where to find occupational and environmental health clinics. Their specialists can recognize, evaluate, and treat illnesses resulting from exposure to hazardous substances. You can also contact your community or state health or environmental quality department if you have any more questions or concerns. For more information, contact:
Agency for Toxic Substances and Disease Registry
U.S. Department of Health and Human Services
|
|