Bureau of Oceans and International Environmental and Scientific Affairs
July 10, 2007
The element Mercury (Hg) is the only metal that is liquid at room temperature and ambient pressure. Mercury is typically found in cinnabar ores, a granular reddish color deposit that is available around the globe; mercury in raw form is gained through mining. Its liquidity at room temperature and its silver color are the reasons it is popularly known as “quicksilver.” In fact, the chemical symbol for mercury, Hg, comes from the Greek "hydrargyrum" meaning liquid silver.
Mercury causes neurological damage in humans and contaminates ecosystems far from its original point of release. Mercury emissions via water, air, or soil cause health problems. When elemental mercury is deposited in water, it is changed into an organic form (methylmercury) by certain microscopic organisms. Eating fish and shellfish that contain methylmercury is the primary pathway for exposure to mercury. Concern about mercury exposure has led EPA and the Food and Drug Administration (FDA) to advise women who may become pregnant, pregnant women, nursing mothers, and young children to avoid some types of fish and to eat types of fish and shellfish that are lower in mercury. Young children and the unborn are particularly vulnerable to methylmercury which can harm the developing brain. Impacts on cognitive thinking, memory, attention, language, and fine motor and visual spatial skills have been seen in children exposed to methylmercury in the womb.
Inhalation of elemental mercury is also a human health concern. This kind of exposure can occur, for example, when products containing elemental mercury – like thermometers -- are broken in poorly ventilated indoor spaces. More information on diagnosing and treating mercury exposure is available from the Center for Disease Control.
Mercury was and is still used in many products and processes. In the mid 1800’s, mercury was used in the felting process to make hats. Exposure to mercury vapors led to widespread cases of mercury poisoning among hatters and gave rise to the expression “mad as a hatter” still in common vernacular today (also giving rise to Lewis Carroll’s famous character in Alice in Wonderland). As a good conductor of electricity, mercury is often used in many products such as switches and batteries. It is used to amalgamate gold and silver in small scale mining activities because it readily combines with other metals. Mercury is currently used in developing countries for certain growing industrial processes, such as vinyl chloride monomer production (VCM) (one source of PVC pipe); and by small scale artisanal gold miners. Use of mercury in artisanal gold mining is already a widely illegal practice but is still used by impoverished workers in many poor countries (especially in remote areas) to extract gold from alluvial deposits.
Active mercury mines are located in China and Kyrgyzstan. Significant deposits of cinnabar are located in the Algeria, Australia, China, Chile, Kyrgyzstan, Peru, Russia, Ukraine, and the United States among others. China, Kyrgyz Republic, Russia, Slovenia, Spain, and Ukraine have most of the world’s estimated 600,000 tons of mercury resources. Other sources of commodity mercury include mercury recovered through recycling programs.
The U.S. geological survey indicates that mercury has not been mined as a primary mineral commodity in the United States since 1992 but is still obtained as a by-product in other mining activities and in natural gas extraction. Current estimates are that more than half of all mercury deposition in the United States comes from sources outside of our boundaries. Coal combustion, significantly tied to economic growth and industrialization in Southeast Asia, is the fastest growing source of mercury emissions affecting air quality and the environment in the United States.
Likewise, the Environmental Protection Agency (EPA) estimates that about one quarter of mercury emissions from U.S. coal-burning power plants are deposited within the contiguous United States and the remainder enters the global atmosphere. Although air emissions are a significant source of global mercury contamination, mercury cycling in the environment also comes from natural sources as well as from releases of mercury used in products and other industrial processes. For more information on domestic and international mercury flows, see the U.S. Geological Survey (USGS) website.
Actions at Home and Abroad to Reduce Mercury Contamination
The United States has made significant progress in reducing mercury use and release:
The U.S. plays a leadership role in international fora addressing mercury risks:
Agenda Item 6: Implementation of the Programme of Work of the United Nations Environment Programme and the Relevant Decisions of the Governing Council; Daniel A. Reifsnyder, Deputy Assistant Secretary for Environment
Fish advisories: http://www.cfsan.fda.gov/seafood1.html
EPA mercury site: http://www.epa.gov/mercury/about.htm
CDC mercury treatment protocols: http://www.atsdr.cdc.gov/MHMI/mmg46.html
First USGS link: http://pubs.usgs.gov/circ/2000/c1197/c1197.pdf
Second USGS link: http://minerals.usgs.gov/minerals/pubs/commodity/mercury/mercumcs07.pdf
Artisanal gold mining: http://www.unido.org/en/doc/4571
EPA Mercury Roadmap: http://www.epa.gov/earlink1/mercury/international.htm
LRTAP Heavy Metals Protocol: http://www.unece.org/env/lrtap/hm_h1.htm
Great Lakes Binational Strategy: http://www.epa.gov/glnpo/bns/index.html
UNEP Mercury Program: http://www.chem.unep.ch/mercury/