Mercury is a naturally occurring metallic element that is found in trace amounts in air, water, and soil. It comes in three forms—elemental, inorganic, and organic. Mercury is familiar to most of us in its elemental form as the heavy, silvery liquid metal used in thermometers, fluorescent light bulbs, and some switches. Inorganic mercury compounds are created when mercury is combined with other elements, such as chlorine, sulfur, or oxygen. It is used in some medications and industrial compounds. Organic mercury compounds are formed when mercury combines with carbon. The most common organic mercury compound, methylmercury, is produced mainly by bacteria in water and soil.

> Link to more information about forms of mercury on the U.S. Environmental Protection Agency Web site.

In nature, mercury tends to be bound up in rocks and soil and is widely dispersed. Much of it is locked away in coal and other geological deposits, where it does not pose a danger to living organisms. However, human activities can release mercury from these natural sources. When humans extract mercury from rocks or burn fossil fuels, it is released into the atmosphere. Airborne mercury can eventually settle into soil and rivers, lakes, and oceans, where aquatic microbes convert it to methylmercury through a biochemical reaction. Fish then absorb methylmercury from the water as it passes over their gills and as they feed on other aquatic organisms. As larger fish eat smaller ones, concentrations of the pollutant increase in the bigger fish, a process known as bioaccumulation. Thus, mercury enters the food chain and becomes concentrated.

People can be exposed to mercury in a number of ways. They may come in contact with mercury from broken thermometers or other spills in the home or workplace. They may breathe in airborne mercury produced by coal-fired power plants, mining operations, or other industrial sources. But by far the most common route of mercury exposure in humans is eating fish contaminated by methylmercury, according to the federal Centers for Disease Control.

> Link to more information about sources of mercury on the U.S. Environmental Protection Agency Web site.

All forms of mercury are poisonous to humans. The severity of effects depends largely on the amount and timing of exposure. Short-term exposure to high concentrations of mercury vapor can cause harmful effects on the nervous, digestive, and respiratory systems, and the kidneys. Chronic exposure can permanently damage the brain and kidneys. Because fetuses, infants, and children are still developing, they are particularly sensitive to the effects of methylmercury on the nervous system, even at low levels of exposure, and data are evolving in support of a link between methylmercury exposure and increased risk of high blood pressure and heart disease at any age.

> Link to more information about health effects of mercury on the U.S. Environmental Protection Agency Web site.

To help protect public health, the Idaho Division of Health through the Idaho Fish Consumption Advisory Program issues fish consumption advisories when fish in water bodies in Idaho are found to have methylmercury levels above what is considered safe. Fish consumption advisories don't mean you should stop eating fish from affected water bodies, but you should be aware of the risks.  Fish are a good source of protein and low in saturated fat. Simply limit fish consumption to amounts specified in the advisory.

> Link to fish advisories currently impacting water bodies in Idaho on the Idaho Department of Health and Welfare Web site.

The need for fish consumption advisories for some Idaho water bodies indicates that mercury pollution is a factor in Idaho , as do the results of water quality studies that show some water bodies in Idaho are impaired and fail to meet water quality standards for mercury.

Sources of mercury pollution in Idaho include a mixture of in-state and out-of-state human-caused and natural processes such as mining operations, petroleum combustion, coal-powered plants, various manufacturing sources, sewage treatment plants, landfills, and other sources.

DEQ has been involved in a number of mercury studies since 2005 aimed at answering, to the extent possible, three critical questions:

• How widespread is mercury in streams, rivers, and lakes in Idaho?
• What concentrations of mercury do we see in water, fish, and soil in Idaho?
• What are the predominant sources of mercury?

> Link to completed mercury studies that will aid in answering one or more of the above questions.

DEQ is working collaboratively with the U.S. Environmental Protection Agency, surrounding state environmental protection agencies, public drinking water systems, the medical community, schools, and others to reduce mercury sources in Idaho. Specific activities include:

• Mercury Deposition Network: DEQ currently has three wet deposition monitors located in Idaho.  These sites are part of the Mercury Deposition Network (MDN). The MDN is a monitoring network currently comprised of more than 85 sites in North America. Its purpose is to develop information on spatial and seasonal trends in mercury deposited via precipitation to surface waters, forested watersheds, and other sensitive areas. The information will be used to help determine how mercury emissions impact human health. Link to more information on the Mercury Deposition Network.

The first MDN site in Idaho was at Craters of the Moon.  It has been in operation since late 2006.  Link to information concerning the Craters of the Moon site.  DEQ is operating two additional wet deposition monitors, one at Lake Lowell in Nampa and the second in McCall.  Data collection in McCall began in late 2007 and data collection began in Nampa in early 2008.  The purpose of these two monitors is to gauge mercury inputs to Brownlee Reservoir and to compare inputs obtained in a dry climate (Nampa) versus an area with more precipitation (McCall). Recent funding for these monitors has come from the Idaho legislature. 

The National Atmospheric Deposition Program (which oversees the MDN) and EPA are currently developing a "dry deposition" network to accompany the wet deposition samplers.  The number of sites will be limited at first due to the high cost of sampling equipment.

• Total Maximum Daily Load Development and Idaho's Mercury Fish Criterion: In April 2005, a new fish tissue criterion for methylmercury was developed as part of DEQ's Water Quality Standards.   The mercury fish tissue criterion will help evaluate whether water quality is impaired by mercury. This, in turn, will enable DEQ to develop and implement water quality improvement plans known as total maximum daily loads (TMDLs) for mercury in water bodies with fish tissue that tests above levels established in the rule. (See Salmon Falls Creek TMDL.)

• Air Quality Permitting: DEQ is the state agency delegated responsibility for administering the federal Clean Air Act in Idaho . This responsibility includes issuing permits that limit the volume of hazardous air pollutants, including mercury, that facilities may emit and conducting inspections of these facilities to assure compliance with federal and state air quality standards. Link to more information on hazardous air pollutants and air quality permitting.

• Practice Greenhealth - Mercury in Healthcare Facilities: Healthcare facilities are under increasing pressure to eliminate mercury.  Good alternatives exist for virtually every mercury containing medical product.  To find information that will help you understand why hospitals have acquired so much mercury, why this has become a problem, what your options are, and a "Ten Step Mercury Guide" to learn how to get mercury out of your facility link to the Practice Greenhealth Web site. Also see DEQ's Greenhealth Web page.

• BMPs for Mercury-Containing Equipment at Public Drinking Water Systems: As the state agency delegated responsibility for administering the federal Safe Drinking Water Act in Idaho, DEQ works closely with local public health districts and public drinking water systems to assure that the water we drink is free of contaminants including mercury. In 2003-04, DEQ conducted an evaluation of equipment used by public drinking water systems in Idaho to identify mercury-containing equipment, including electric switches, sensors, gauges, and meters, with a potential to contaminate drinking water. A technical guide was completed and is available to provide system operators with best management practices to prevent mercury-containing equipment from contaminating drinking water.

• Hazardous Waste Regulation: Every business in Idaho is required to track the volume of wastes generated, determine whether or not each is hazardous, and ensure that all wastes are properly disposed of according to federal, state and local requirements. As the state agency delegated responsibility for administering the federal Resource Conservation and Recovery Act in Idaho, DEQ works closely with businesses to assure that hazardous wastes, including mercury, are transported, stored, and disposed of safely.

• National Vehicle Mercury Switch Replacement Program: DEQ participates in the National Vehicle Mercury Switch Replacement Program.  Idaho auto recyclers and salvage yards have been invited to voluntarily participate in this program to remove mercury switches from vehicles before the vehicles are crushed and recycled.  The End of Life Vehicle Solutions Corporation implements this program and offers a $4 payment for every mercury switch that is returned for recycling.  For information to participate in this program, contact John Brueck at (208) 373-0458 or john.brueck@deq.idaho.gov. 

• School Labs Chemical Management and Cleanup Project: In a study conducted by DEQ in 2003-04, it was revealed that a number of schools in Idaho have amassed large stockpiles of hazardous products on school grounds and lack knowledge of secure management and safe disposal procedures for hazardous chemicals and waste. Mercury was among the hazardous materials discovered at some school labs. DEQ's Idaho Chemical Roundup program was developed to assist schools in understanding and implementing best practices for managing and disposing of their hazardous chemicals and wastes, including mercury.

• Public Education and Outreach: DEQ is working to increase public awareness of risks associated with mercury exposure and ways to reduce releases of mercury into the environment.

DEQ plans on investigating mercury in rivers in Idaho, by collecting fish at a number of randomly selected sites across Idaho, similar to what was done for lakes in 2007.  The fish collected at these sites will be analyzed for mercury and those results compared to our mercury fish tissue criterion.  DEQ expects a report on this effort late winter or early spring of 2009. 

Through an ongoing contract with the USGS, additional fish tissue samples will be collected at six gauging sites in Idaho.  Those fish samples will be analyzed for mercury and reported back to DEQ. 

DEQ is undertaking development of a comprehensive mercury database for water, fish, and soil.  This database will hold the ever-increasing mercury data DEQ is collecting along with that collected for us by the USGS.  This database will facilitate analysis of statewide mercury conditions in various water body types and locations around Idaho.  DEQ intends to make the data in this database available to the public along with a fish calculator that will enable people to enter their weight and determine consumption advice based on specific mercury fish tissue data. 

Mercury pollution prevention is an effort showed by government. Individuals and businesses playing an equal role. Here are some things you can do to help reduce the threat mercury poses to our environment and health:

For more information on what to do if you have a mercury spill, click here.