mercury poisoning(redirected from Mercury poisoning, nervous system)
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mercury poisoning,tissue damage resulting from exposure to more than trace amounts of the element mercurymercury
[from the Roman god Mercury], metallic chemical element; symbol Hg [Lat. hydrargyrum=liquid silver]; at. no. 80; at. wt. 200.59; m.p. −38.842°C;; b.p. 356.58°C;; sp. gr. 13.55 at 20°C;; valence +1 or +2.
..... Click the link for more information. or its compounds. Elemental mercury (the silver liquid familiar from thermometers) is the most common occupational source. Exposure typically comes from inhaling mercury vapors. Inorganic salts of mercury (e.g., mercurous chloride, or calomel) are used in some products to inhibit the growth of fungi and bacteria. Organic mercury compounds, especially methylmercury, are more toxic than other forms because they easily cross cell membranes. They are most often ingested in contaminated fish.
Mercury poisoning can cause severe neurological and kidney damage. Acute exposure can affect the respiratory and gastrointestinal systems. Organic mercury can cross the blood-brain barrier and cause irreversible nervous system and brain damage, e.g., loss of motor control, numbness in limbs, blindness, and inability to speak. Some studies have connected maternal mercury exposure to fetal damage. Mercury poisoning can be confirmed by urine tests. Chelation therapy is used for poisoning with elemental mercury and mercury salts; there is no treatment for organic mercury poisoning.
Mercury has become an environmental pollutant in areas where eroding mercury-bearing rock or agricultural and industrial wastes containing the metal escape or are discharged into waterways. Mercury also is released into the atmosphere when coal is burned. Elemental mercury and mercury salts, although fairly inert when deposited on the bottom of waterways, are converted into organic mercury, typically methylmercury, by microorganisms. This compound then enters the food chain where it is biomagnified up to 100,000 times in predacious fish. Consumption of toxic fish and of game birds and mammals that feed on fish is the main risk to humans. Minamata disease was named after the occurrence, in the 1950s and 1960s in Minamata, Japan, of many cases of severe mercury poisoning. It was found that a chemicals factory was discharging mercury-containing wastes into the local waters, contaminating fish that residents caught for food.
Mercury has long been known to be toxic; the phrase "mad as a hatter" refers to the 19th-century occupational disease that resulted from prolonged contact with the mercury used in the manufacture of felt hats. Some workers today, especially laboratory technicians, nurses, and machine operators, continue to be exposed to mercury on the job. Most mercury pesticides have been withdrawn from the U.S. market, and many countries banned ocean dumping of mercury and other pollutants in 1972. Production of mercury-containing interior and exterior paints in the United States was phased out in 1991. The Minamata Convention, adopted in 2013, requires its signatories to reduce both mercury use and emissions. Mercury, which has been used in medicines for hundreds of years, continues to be used in dental amalgams and various medicaments that deliver minimal exposures. Most other medical uses have been banned or are being phased out, but mercury use in industry is increasing.
See also water pollutionwater pollution,
contamination of water resources by harmful wastes; see also sewerage, water supply, pollution, and environmentalism. Industrial Pollution
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See L. Elbert, Mercury Poisoning in Man (1978); P. A. and F. M. D'itri, Mercury Contamination: A Human Tragedy (1988).
mercurialism, an occupational disease; poisoning by metallic mercury or its compounds.
Mercury poisoning results from contact with fumes of mercury metal or its amalgams and readily decomposing compounds or from the accidental ingestion of mercury salts. Acute mercury poisoning is characterized by fever and necrotic ulcerative lesions of the oral and intestinal mucosae. Severe kidney lesions are dominant in poisoning by mercury salts. Chronic mercury
|Table 1. Launches of Mercury spacecraft|
|code designation of vehicle||Date of launon||Elements of orbit (km)||Period of revolution(min)||Length of flight||Type of flight (name of astronaut)|
|MR-3 .....||May 5, 1961||–||–||–||–||15 min||Suborbital (A. Shepard)|
|MR-4 .....||July 21, 1961||–||–||–||–||16 min||Suborbital V. Grissom)|
|MA-6 .....||Feb. 20, 1962||161.4||262.8||32.5||88.2||4 hr 55 min||Orbital (J. Glenn)|
|MA-7 ....||May 24, 1962||160.9||268.4||32.5||88.3||4 hr 56 min||Orbital (M. Carpenter)|
|MA-8 ....||Oct. 3, 1962||161.4||278.2||32.56||88.9||9 hr 13 min||Orbital (W. Schirra)|
|MA-9 .....||May 15, 1963||160.9||267||32.5||88.7||34 hr 20 min||Orbital (G. Cooper)|
poisoning involves damage to the central nervous system (increased excitability and rapid fatigability of neural processes, increasing involuntary tremor in the extremities). Mental changes and severe systemic exhaustion (mercury cachexia) develop with the passage of time. Mercury’s ability to penetrate the placenta can lead to poisoning of the fetus in pregnant women.
Mercury poisoning is treated with antidotes and drugs that help to remove the mercury from the body. Hydrogen sulfide baths are also useful. The condition can be prevented by observing safety standards in dealing with mercury.
REFERENCESKevork’ian, A. A. ProfessionaVnye neirotoksikozy. Minsk, 1955.
Drogichina, E. A. Prefessionarnye bolezni nervnoi sistemy. [Leningrad] 1968.
Trakhtenberg, I. M. Khronicheskoe vozdeistvie rtuti na organizm. Kiev, 1969.
A. A. BEZRODNYKH