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What is Mercury

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mercury in water
  What is mercury?  Mercury is a liquid metal found in natural deposits such as ores containing other elements. Uses for mercury. Electrical products such as dry-cell batteries, fluorescent light bulbs, switches, and other control equipment account for 50 percent of mercury used. If you are concerned about mercury in a private well, please visit:    EPA's private drinking water wells website     Water Systems Council website  What are mercury s health effects?  Some people who drink water containing mercury well in excess of the maximum contaminant level (MCL) for many years could experience kidney damage. This health effects language is not intended to catalog all possible health effects for mercury. Rather, it is intended to inform consumers of some of the possible health effects associated with mercury in drinking water when the rule was finalized. Top of page  What are EPA s drinking water regulations for mercury?  In 1974, Congress passed the Safe Drinking Water Act. This law requires EPA to determine the level of contaminants in drinking water at which no adverse health effects are likely to occur. These non-enforceable health goals, based solely on possible health risks and exposure over a lifetime with an adequate margin of safety, are called maximum contaminant level goals (MCLG). Contaminants are any physical, chemical, biological or radiological substances or matter in water. The MCLG for mercury is 0.002 mg/L or 2 ppb. EPA has set this level of protection based on the best available science to prevent potential health problems. EPA has set an enforceable regulation for mercury, called a maximum contaminant level (MCL), at 0.002 mg/L or 2 ppb. MCLs are set as close to the health goals as possible, considering cost, benefits and the ability of public water systems to detect and remove contaminants using suitable treatment technologies. In this case, the MCL equals the MCLG, because analytical methods or treatment technology do not pose any limitation. The Phase II Rule, the regulation for mercury, became effective in 1992. The Safe Drinking Water Act requires EPA to periodically review the national primary drinking water regulation for each contaminant and revise the regulation, if appropriate. EPA reviewed mercury as part of the  Six Year Review and determined that the 0.002 mg/L or 2 ppb MCLGand 0.002 mg/L or 2 ppb MCL for mercury are still protective of human health.    More information on the Six Year Review of Drinking Water Standards. States may set more stringent drinking water MCLGs and MCLs for mercury than EPA. Top of page  How does mercury get into my drinking water?  The major sources of mercury in drinking water are erosion of natural deposits; discharge from refineries and factories; runoff from landfills; and runoff from croplands. A federal law called the Emergency Planning and Community Right to Know Act (EPCRA) requires facilities in certain industries, which manufacture, process, or use significant amounts of toxic chemicals, to report annually on their releases of these chemicals. For more information on the uses and releases of chemicals in your state, contact the Community Right-to-Know Hotline: (800) 424-9346.    EPA's Toxics Release Inventory (TRI) website provides information about the types and amounts of toxic chemicals that are released each year to the air, water, and land. Top of page  How will I know if mercury is in my drinking water?  When routine monitoring indicates that mercury levels are above the MCL, your water supplier must take steps to reduce the amount of mercury so that it is below that level. Water suppliers must notify their customers as soon as practical, but no later than 30 days after the system learns of the violation. Additional actions, such as providing alternative drinking water supplies, may be required to prevent serious risks to public health.    See EPA's public notification requirements for public water systems. If your water comes from a household well, check with your health department or local water systems that use ground water for information on contaminants of concern in your area.    For more information on wells, go to EPA's website on private wells. Top of page  How will mercury be removed from my drinking water?  The following treatment method(s) have proven to be effective for removing mercury to below 0.002 mg/L or 2 ppb: coagulation/filtration, granular activated carbon, lime softening, and reverse osmosis.  Top of page  Mercury in Water and Drinking Water Elemental mercury is typically released from industrial processes, agricultural  processes, household, commercial and medical products containing mercury, sewage discharge and sediment. Elemental mercury vapor may cause nervous system damage when exposed at high concentrations. Inorganic mercury is found in batteries and is used in the chemical industry and it is  produced from elemental mercury through the process of oxidation. Inorganic mercury is the most common form that is present in drinking water but is not considered to be very harmful to human health, in terms of the levels found in drinking water. However, kidney damage may result from exposure to inorganic mercury through other sources. . Organic mercury (primarily methyl mercury) is  produced by specific bacterial organisms in surface waters that convert inorganic mercury into organic mercury, which is the form of mercury that poses a significant threat to human health. Methyl mercury is ingested typically by fish and bioaccumulates both in the tissues of fish and the humans that eat these fish. Large  predatory fish can contain as much as 100,000 times more methyl mercury than the surrounding water medium. This form is rarely  present in drinking water but is a very common contaminant in the tissues of fish and causes damage to the nervous system as well as teratogenesis. Both inorganic and organic mercury are considered to have a more detrimental effect on children due to the fact that both forms are more easily absorbed into their system.   In 1974, the EPA established the Safe Drinking Water Act that set specific guidelines on contaminants that are commonly found in drinking water. However, it was not until 1992 that mercury, in particular, became regulated. Both the Maximum Contaminant Level Goal and the Maximum Contaminant Level were set at 2 parts per  billion because current technology allows public water suppliers to detect and remove mercury levels that low. The monitoring of mercury levels must take place every three months if the level is higher than the set guideline and specific measures must be taken to reduce these levels if they are exceeded persistently. Approved methods of removing mercury from the drinking water supply are the following: Coagulation/Filtration, Granular Activated Carbon, Lime softening and Reverse osmosis.
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