Human Health

Health problems caused by mercury depend on how much has entered your body, how it entered your body, how long you have been exposed to it, and how your body responds to the mercury. People are at risk when they consume mercury-contaminated fish and when they are exposed to spilled mercury.

Elemental (metallic) mercury and its compounds are toxic and exposure to excessive levels can permanently damage or fatally injure the brain and kidneys. Elemental mercury can also be absorbed through the skin and cause allergic reactions. Ingestion of inorganic mercury compounds can cause severe renal and gastrointestinal toxicity. Organic compounds of mercury such as methylmercury are considered the most toxic forms of the element. Exposures to very small amounts of these compounds can result in devastating neurological damage and death.

For fetuses, infants and children, the primary health effects of mercury are on neurological development. Even low levels of mercury exposure such as result from mother's consumption methylmercury in dietary sources can adversely affect the brain and nervous system. Impacts on memory, attention, language and other skills have been found in children exposed to moderate levels in the womb.

All mercury spills, regardless of quantity, should be treated seriously. Metallic mercury slowly evaporates when exposed to the air. The air in a room can reach contamination levels just from the mercury in a broken thermometer. Mercury in school labs should be handled with care and stored safely and securely.

Mercury pollution is released into the air from the burning of fossil fuels. It falls down directly onto waterways or is deposited on land where it can be washed into the water. Bacteria in the water cause chemical changes that transform mercury into a highly toxic form - methylmercury.

Methylmercury accumulates in fish, with larger fish generally accumulating higher levels of methylmercury. If you are pregnant or could become pregnant, are nursing a baby, or if you are feeding a young child, you should limit consumption of freshwater fish caught by family and friends to one meal per week. For adults one meal is six ounces of cooked fish or eight ounces uncooked fish; for a young child one meal is two ounces cooked fish or three ounces uncooked fish. Many states collect data on mercury levels in fish from local waters and issue fish consumption advisories.

For more information on freshwater fish consumption advisories across the country, go to http://map1.epa.gov/.

Additional Information

"Mercury Health Hazards" - The National Institutes of Health provides information on how mercury affects health including occupational exposure.

"Reducing Mercury Use In Health Care" - This EPA manual helps hospitals start or improve mercury pollution prevention programs.

MedlinePlus offers health information from the National Library of Medicine.

Advisory on Methylmercury in Fish, US Food and Drug Administration - The US FDA has issued guidelines on the consumption of certain commercial seafood that might be contaminated with mercury.

Mercury Research Strategy - EPA's plan for mercury research, covering the FY2001 – 2005 timeframe. It describes the human health and ecological risks posed by mercury and indicates that mercury should be considered on local, regional, and global scales. The Strategy identifies the most important scientific questions for EPA and then describes a research program to answer those questions.

Agency for Toxic Substances and Disease Registry Mercury Factsheet - ATSDR's toxicological factsheet which answers the frequently asked health questions about mercury.

Agency for Toxic Substances and Disease Registry Metallic Mercury Exposure Alert - ATSDR's National Alert about metallic mercury in school and ritual use.

IRIS Health Assessment for Mercury and Methylmercury - Human health effects that may result from exposure to mercury or methylmercury (select from drop-down box). Part of the Integrated Risk Information System (IRIS) database.

Tox Town - The world's largest medical library, the US National Library of Medicine, a part of the National Institutes of Health, has developed an introductory Web site about toxic chemicals and environmental health risks such as mercury, lead, and asbestos in the towns and cities where you live.

Health Care Without Harm is a nongovernment agency that provides information about reducing the use of mercury in health care.