Mercury

For more information on Mercury, please contact:

Marti Otto
Technology Assessment Branch
(703) 603-8853
otto.martha@epa.gov

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Toxicology

Mercury (Hg) is a highly toxic element that is found both naturally and as an introduced contaminant in the environment. Although its potential for toxicity has been demonstrated dramatically in highly contaminated areas such as Minamata Bay, Japan, in the 1950s and 60s, research has shown that mercury can be a thgot reat to the health of people and wildlife in many environments that are not obviously polluted. The risk is determined by the route of exposure, the form (species) of mercury present (some forms are more toxic or bioavailable than others), and the geochemical and ecological factors that influence how mercury moves and changes form in the environment.

There are many similarities in the toxic effects of the various mercury species, but also significant differences. The organic mercury compounds include methylmercury, methylmercuric chloride, dimethylmercury, and phenylmercuric acetate. Microorganisms in the environment can alter inorganic mercury to an organic form, such as methylmercury (MeHg, or CH₃Hg), which is the most common organic form. It affects the immune system, alters genetic and enzyme systems, and damages the nervous system, including coordination and the senses of touch, taste, and sight. Exposure to methylmercury usually occurs through ingestion (i.e., eating contaminated fish and wildlife), and when ingested, it is absorbed more readily and excreted more slowly than other forms of mercury. Exposure to organic mercury from food results in an absorption six times greater than the same amount of inorganic mercury. Soluble organic mercury is absorbed readily from the gastrointestinal tract, while inorganic mercury is absorbed only very sparingly.

Metallic or elemental mercury and the inorganic salts, including mercurous chloride, mercuric chloride, mercuric acetate, and mercuric sulfide, are classified under the general heading of inorganic mercury. Elemental mercury (Hg⁰), the familiar silvery liquid form released from broken thermometers, and its accumulation in the body through inhalation of vapors can cause tremors, gingivitis, and excitability, and even death at high levels of accumulation or exposure. Elemental mercury can be found in higher concentrations in environments such as gold mine sites, where it is used to extract gold. If elemental mercury is ingested, it is absorbed relatively slowly (unlike inhaled elemental mercury) and may pass through the digestive system without causing damage.

Jump to a Subsection Human Health | Ecological Impacts

Human Health

List of References for Methylmercury Human Health Affects
U.S. EPA Website.

Mercury, elemental (CASRN 7439-97-6)
U.S. EPA. Integrated Risk Information System (IRIS).

Mercury Study Report to Congress Volume IV: An Assessment of Exposure to Mercury in the United States
U.S. EPA, Office of Air Quality Planning & Standards and Office of Research and Development.
EPA 452-R-97-006, 1997.
Contact: Kathryn R. Mahaffey, mahaffey.kate@epa.gov

Mercury Study Report to Congress Volume V: Health Effects of Mercury and Mercury Compounds
U.S. EPA, Office of Air Quality Planning & Standards and Office of Research and Development.
EPA 452-R-97-007, 349 pp., 1997.
Contact: Kathryn R. Mahaffey, mahaffey.kate@epa.gov

Mercury Study Report to Congress Volume VII: Characterization of Human Health and Wildlife Risks from Mercury Exposure in the United States
U.S. EPA, Office of Air Quality Planning & Standards and Office of Research and Development.
EPA 452-R-97-009, 152 pp., 1997.
Contact: Kathryn R. Mahaffey, mahaffey.kate@epa.gov

Methylmercury (MeHg) (CASRN 22967-92-6)
U.S. EPA. Integrated Risk Information System (IRIS).

New Jersey Mercury Task Force Report, Volume II: Exposure and Impacts
New Jersey Department of Environmental Protection, 2002.
Contact: Leslie McGeorge, 609-292-1623

Public Health Goal for Inorganic Mercury In Drinking Water
California Environmental Protection Agency, Office of Environmental Health Hazard Assessment, 1999.
Contact: Lubow Jowa, 916-327-7327

Task Force on Ritualistic Uses of Mercury Report
U.S. EPA.
EPA 540-R-01-005, OSWER 9285.4-07, 111 pp., 2002.

The task force undertook an examination of human exposure to mercury due to the use of elemental mercury as part of certain spiritual practices and folk traditions.

Third National Report on Human Exposure to Environmental Chemicals
Department of Health and Human Services, Center for Disease Control, Atlanta, GA. NCEH Publication 05-0570, 475 pp, 2005.

This report series provides an ongoing assessment of the U.S. population's exposure to environmental chemicals by measuring the chemicals or their metabolites in human specimens, such as blood or urine. The report coverage includes metals (e.g., mercury), PCBs, dioxins, polycyclic aromatic hydrocarbons, pthalates, and numerous pesticides. The report is designed to allow users to determine public health information in the following areas: (1) which chemicals get into Americans and at what concentrations, (2) prevalence of people with chemical levels above those of chemicals with a known toxicity level, (3) reference ranges that can be used by physicians and scientists to determine whether a person or group has an unusually high exposure, (4) effectiveness of public health efforts to reduce exposure of Americans to specific chemicals, (5) exposure levels among minorities, children, women of childbearing age, or other potentially vulnerable groups, (6) trends in levels of exposure of the population, and (7) priorities for research on human health effects.

Toxicological Effects of Methylmercury
National Research Council, Committee on the Toxicological Effects of Methylmercury.
National Academies Press, Washington, DC. ISBN: 0-309-07140-2, 368 pp., 2000.

Toxicological Profile for Mercury
Agency for Toxic Substances and Disease Registry, 1999.
Contact: ATSDR Information Center, ATSDRIC@cdc.gov, 1-888-422-8737

TOXNET
National Library of Medicine Specialized Information Services.

This site contains a cluster of databases on toxicology, hazardous chemicals, and related areas, including the Hazardous Substances Data Bank (HSDB), Integrated Risk Information System (IRIS), and Toxics Release Inventory (TRI). The site supports simultaneous searching in multiple databases.

Workshop on the Scientific Issues Relevant to Assessment of Health Effects from Exposure to Methylmercury, November 18-20, 1998

A U.S. interagency committee organized this workshop to discuss and evaluate the major epidemiological studies associating methylmercury exposure with an array of developmental measures in children.

Ecological Impacts

Development of an Ecological Risk Assessment Methodology for Assessing Wildlife Exposure Risk Associated with Mercury-Contaminated Sediments in Lake and River Systems
C.D. Knightes and R.B. Ambrose Jr.
EPA 600-R-06-073, 80 pp, 2006

ECOTOX Database
U.S. EPA Website.

The ECOTOX database provides single chemical toxicity information for aquatic and terrestrial life. Peer-reviewed literature is the primary information source, supplemented by data files provided by various government agencies.

Mercury Hazards to Fish, Wildlife, and Invertebrates: a Synoptic Review
Eisler, Ronald, U.S. Fish and Wildlife Service, Patuxent Wildlife Research Center, Laurel, MD.
U.S. Fish and Wildlife Service, Biological Report 85(1.10), Contaminant Hazard Reviews #10, April 1987
Contact: Ronald Eisler, Ronald_Eisler@usgs.gov

Mercury (Mercury in General, Hg, CAS number 7439-97-6)
Environmental Contaminants Encyclopedia, R.J. Irwin, M. VanMouwerik, L. Stevens, M.D. Seese, and W. Basham (compilers). National Park Service, Water Resources Division, Fort Collins, CO. 108 pp., 1997.
Contact: Roy Irwin, roy_irwin@nps.gov

Methods/Indicators for Determining When Metals Are the Cause of Biological Impairments of Rivers and Streams: Species Sensitivity Distributions and Chronic Exposure-Response Relationships from Laboratory Data
P. Shaw-Allen and G.W. Suter II, U.S. EPA, Cincinnati, OH.
Report No: EPA 600-X-05-027, pp, July 2005

Provides information on the effects of the common aquatic metal contaminants (cadmium, chromium, copper, lead, mercury, nickel, and zinc, plus arsenic and selenium) on laboratory animals for use in the strength-of-evidence step of the stressor identification process to help determine whether metals contribute to biological impairments.

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Last updated on Monday, April 7, 2008