Mercury drinking water contamination

Until now there has been no effective technology for reducing groundwater mercury to two parts per billion, as required by the maximum contamination limit for drinking water established by the U.S. Food and Drug Administration and the U.S. EPA. 

Arsenic is an ancient and well-known hazard and, along with lead and mercury, is an important environmental contaminant. The inorganic form is far more toxic than organic arsenic, which is commonly found in seafood. Arsenic-contaminated drinking water is a worldwide problem that affects millions of people. Human exposure also occurs from arsenic-treated lumber. 

There are virtually no sources of drinking water on Earth that are not contaminated with xenobiotics. Rain water cleanses the atmosphere as it forms and falls. As a result, it contains dissolved acids, organic compounds, and heavy metals such as mercury and selenium in many areas. Surface collection basins from which potable water is drawn—rivers, streams, and lakes—accumulate ground level pollutants in addition to those carried in rain water. Underground water, which is somewhat filtered and generally contains lesser quantities of pollutants than surface water, may itself be contaminated by ground releases of toxicants and by contaminants produced by chemical reactions in the soil and water. 

Nature cannot be subjected to increasing concentrations of man-made substances that natural systems will not purge. Example The emissions of pesticides, PCBs, mercury, chloro-fluorocarbons, mine wastes, and innumerable other toxics and cancer-causing substances have contaminated food supplies, drinking water, ecosystems, and every human body on the planet. 

US EPA. Maximum contaminant level for mercury, http //water.epa.gov/drink/contaminants/ basicinformation/mercury.cfin [accessed on 20.05.15]. 

By law, the maximum contamination level of lead in drinking water is 0.05 ppm. This number corresponds to 0.05 milligrams of lead per liter of water. That s pretty dilute. But mercury is regulated at the 0.002 ppm level. Sometimes, even this unit isn t sensitive enough, so environmentalists have resorted to the parts per billion (ppb) or parts per trillion (ppt) concentration units. Some neurotoxins are deadly at the parts per billion level. 

Normally, the body burden of mercury in humans is predominantly caused by the diet [2,14] and the dental amalgam [15]. Other sources, such as air or drinking water, contribute substantially to the total burden only in the case of local mercury contaminations [2]. 

The Safe Drinking Water Act (SDWA) sets a limit for mercury—a toxin to the central nervous system—at 0.002 mg/L. Water suppliers must periodically test their water to ensure that mercury levels do not exceed 0.002 mg/L. Suppose water became contaminated with mercury at twice the legal limit (0.004 mg/L). How much of this water would have to be consumed to ingest 0.100 g of mercury ... 

Some advanced industrial nations have established strict guidelines for water supply facilities to protect their citizens from the adverse effects of toxicity and hazardous materials. Some countries have set up maximum contaminant levels (MCLs) beyond which the drinking water is considered unhealthy. The MCL established by the United States for lead is 0.05 mg/L and for cadmium is 0.01 mg/L. The United States has not defined an MCL for nickel. Specific detailed on adverse effects of lead, cadmium, mercury, nickel, and their compounds are well documented in the U.S. Environmental Protection Agency list. This list contains the Toxic Release Inventory (TRI) for chemicals, and the list is updated every five years. 

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