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CAS Number: 7439-97-6
Synonyms: Hg(0), Hg(2), hydrargyrum, quicksilver
Contaminant Type: Chemical

Mercury is a naturally occurring element found in air, water, and soil.  Mercury can exist in elemental, inorganic, or organic forms. The most common forms of mercury existing in the environment are metallic mercury, mercuric sulfide, mercuric chloride, and methylmercury.  Microorganisms (bacteria and fungi) and other natural processes can change mercury from one form to another [648].

In the past, mercury was used primarily as a fungicide, antibacterial agent, paint dye, and preservative.  It has since been replaced by safer and more effective agents.  Today, one-third to two-thirds of the mercury released is the result of human related activity.  Approximately 80 percent of mercury released by humans is from fossil fuel combustion, mining, and smelting. Released as elemental mercury, the compound combines with other inorganic compounds and settles on lands and in streams. Fifteen percent of human released mercury is released to the soil from fertilizers, fungicides, and municipal solids wastes, and the remaining 5 percent is released from industrial wastewater [648].

The consumption of contaminated fish is one of the bigger causes of mercury poisoning in addition to exposure in the workplace.  Permanent damage to the brain, kidneys, and nervous system often result from the ingestion of high mercury doses.  Organic mercury compounds are especially dangerous because they adsorb into the body much more readily than elemental or inorganic mercury.  Mercury poisoning in children or a developing fetus are more extreme; often affecting brain and nervous system development [648].

Inorganic mercury is regulated in drinking water in the US with a MCL of 0.002 mg/L. The United State Environmental Protection Agency has identified several treatment processes as Best Available Technologies (BATs) for control of mercury in drinking water. They are: conventional treatment, granular activated carbon, lime softening, and reverse osmosis [1267].

Because of human related activities, mercury can be detected in both groundwater and surface water supplies.  Treatment of mercury is often the result of human related releases (to air or soil) and not to naturally occurring mercury in the groundwater.

Date of Literature Search: June 2009

648 U.S. Department of Health and Human Services; 1999; Toxicological Profile for Mercury; Toxicological Profile for Mercury; 363-370: Agency for Toxic Substances and Disease Registry
1267 US Government; 2009; Electronic Code of Federal Regulations; Title 40, Part 141.62 Maximum contaminant levels for inorganic contaminants; http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=a05e26cfb3d8ea7be7ac637c411c4c39&rgn=div8&view=text&node=40:; As posted on August 27, 2009. United States Government.