Formula. X stands for any anion

3D model

Methylmercury (sometimes methyl mercury) is an organometallic cation with the formula [CH₃Hg]⁺. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Organometallic chemistry is the study of Chemical compounds containing bonds between Carbon and a Metal. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge It is a bioaccumulative environmental toxicant. Bioaccumulation occurs when an organism absorbs a toxic substance at a rate greater than that at ftudruinsubstance is lost

Basic chemical description

"Methylmercury" is a shorthand for monomethylmercury, and is more correctly "monomethylmercuric cation". It is composed of a methyl group (CH₃-) bonded to a mercury atom; its chemical formula is CH₃Hg⁺ (sometimes written as MeHg⁺). In Chemistry, a methyl group is a Hydrophobic Alkyl Functional group named after Methane (4 In Organic chemistry, functional groups are specific groups of Atoms within Molecules that are responsible for the characteristic Chemical reactions Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 A chemical bond is the physical process responsible for the attractive interactions between Atoms and Molecules and which confers stability to diatomic and polyatomic Mercury (ˈmɜrkjʊri also called quicksilver or hydrargyrum, is a Chemical element with the symbol Hg ( Latinized hydrargyrum History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Mercury (ˈmɜrkjʊri also called quicksilver or hydrargyrum, is a Chemical element with the symbol Hg ( Latinized hydrargyrum As a positively charged ion it readily combines with anions such as chloride (Cl^-), hydroxide (OH^-) and nitrate (NO₃^-). An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge The chloride Ion is formed when the element Chlorine picks up one Electron to form an Anion (negatively-charged ion Cl&minus Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and In Chemistry, hydroxide is the most common name for the diatomic Anion OH− consisting of Oxygen and Hydrogen Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 In Inorganic chemistry, a nitrate is a salt of Nitric acid with an Ion composed of one Nitrogen and three Oxygen atoms Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the It also has very high affinity for sulfur-containing anions, particularly the sulfhydryl (-SH) groups on the amino acid cysteine and hence in proteins containing cysteine, forming a covalent bond. Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 In Organic chemistry, a thiol is a compound that contains the functional group composed of a Sulfur atom and a Hydrogen atom (-SH Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this Not to be confused with Cystine, its oxidized dimer Cysteine (abbreviated as Cys or C) is an α- Amino acid with Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl More than one cysteine moiety may coordinate with methylmercury^[1] and methylmercury may migrate to other metal-binding sites in proteins. ^[2]

Sources of methylmercury

Environmental sources

In the past times, methylmercury was produced directly and indirectly as part of several industrial processes such as the manufacture of acetaldehyde. Acetaldehyde, sometimes known as ethanal, is an organic chemical compound with the formula C[[Hydrogen H]]3CH O or MeCHO Currently there are few anthropogenic sources of methylmercury pollution other than the burning of wastes containing inorganic mercury and from the burning of fossil fuels, particularly coal. Anthropogenic effects processes objects or materials are those that are derived from Human activities as opposed to those occurring in Natural environments without Pollution is the introduction of contaminants into an environment that causes instability disorder harm or discomfort to the physical systems or living organisms they are in Combustion or burning is a complex sequence of Exothermic chemical reactions between a Fuel and an Oxidant accompanied by the production of Fossil fuels or mineral fuels are fossil source Fuels that is Hydrocarbons found within the top layer of the Earth’s crust. Although inorganic mercury is only a trace constituent of such fuels, their large scale combustion in the United States alone results in release of some 48 tons of elemental mercury to the atmosphere each year. Traditionally inorganic compounds are considered to be of mineral not biological origin The United States of America —commonly referred to as the Units of mass There are three similar units of Mass called the ton: Long ton (simply ton in countries such as the United Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five About three times as much additional inorganic mercury is contributed by natural sources such as volcanoes, forest fires and weathering of mercury-bearing rocks. Plate tectonics and hotspots Divergent plate boundaries At the A wildfire, also known as a wildland fire, forest fire, brush fire, vegetation fire, grass fire, Peat fire, Weathering is the decomposition of earth rocks, Soils and their Minerals through direct contact with the planet's Atmosphere. Cinnabar, sometimes written cinnabarite, is a name applied to red Mercury(II sulfide ( Hg[[sulfide S]] or native Vermilion, the common In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere ^[3] Methylmercury is formed from inorganic mercury by the action of anaerobic organisms that live in aquatic systems including lakes, rivers, wetlands, sediments, soils and the open ocean. An anaerobic organism is any Organism that does not require Oxygen for growth and may even die in its presence A lake (from Latin lacus) is a Terrain feature (or Physical feature) a body of Liquid on the surface of a world that is localized to the "Riverine" redirects here For the use of that term in Maritime geography, see there A wetland is an area of Land consisting of Soil that is Saturated with Moisture, such as a Swamp, Marsh, or Bog Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of Soil, often typeset as SOiL, is a four piece rock band from Chicago Illinois United States founded by Shaun Glass Tom Schofield Tim King and Adam Zadel An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere.

Dietary sources

Because methylmercury is formed in aquatic systems and because it is not readily eliminated from organisms it is biomagnified in aquatic food chains from bacteria, to plankton, through macroinvertebrates, to herbivorous fish and to piscivorous (fish-eating) fish. Biomagnification, also known as bioamplification, or biological magnification is the increase in concentration of a substance such as the Pesticide Food chains, also called food networks and/or trophic networks, describe the feeding relationships between species within an Ecosystem. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have Plankton consist of any drifting Organisms ( Animals Plants Archaea, or Bacteria) that inhabit the Pelagic zone of An invertebrate is an Animal lacking a Vertebral column. The group includes 98% of all animal Species — all animals except those in the Chordate Herbivory is a form of Predation in which an Organism, known as a herbivore, consumes principally Autotrophs ref name=Campbell>Campbell Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two At each step in the food chain, the concentration of methylmercury in the organism increases. In Chemistry, concentration is the measure of how much of a given substance there is mixed with another substance The concentration of methylmercury in the top level aquatic predators can reach a level a million times higher than the level in the water. This is because methylmercury has a half-life of about 72 days in aquatic organisms, attributing to its bioaccumulation within these food chains. Organisms, including humans,^[4] fish-eating birds, and fish eating mammals such as otters and whales that consume fish from the top of the aquatic food chain receive the methylmercury that has accumulated through this process. Otters are semi- aquatic (or in one case aquatic) fish-eating Mammals The otter subfamily Lutrinae forms part of the family Whales are marine mammals which are neither Dolphins (ie members of the families Delphinidae or Platanistoidae) nor Porpoises Orcas Fish and other aquatic species are the only significant source of human methylmercury exposure. In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank.

The concentration of mercury in any given fish depends on the species of fish, the age and size of the fish and the type of water body in which it is found. In general, fish-eating fish such as shark, swordfish, marlin, larger species of tuna, walleye, largemouth bass, and chain pickerel have higher levels of methylmercury than herbivorous fish or smaller fish such as tilapia, and herring. Sharks ( Superorder Selachimorpha) are a type of Fish with a full cartilaginous Skeleton and a highly streamlined body Swordfish ( Xiphias gladius) are large highly migratory Predatory Fish characterized by a long flat bill. Marlin, Istiophoridae, is a member of a larger grouping of marine Fishes known as "billfish" of which several are popular in Big-game fishing Tuna, are several Species of ocean-dwelling Fish in the family Scombridae, mostly in the genus Thunnus. The walleye (common US name or yellow pickerel (Canada ( Sander vitreus vitreus, formerly Stizostedion vitreum vitreum) is a freshwater Perciform The largemouth bass ( Micropterus salmoides) is a Species of Fish in the sunfish family. The chain pickerel, Esox niger ( syn Esox reticulatus) is a Species of Freshwater Fish in the pike family Tilapia (təˌlɑpiə is the common name for nearly a hundred Species of Cichlid Fishes from the Tilapiine cichlid tribe Herring are small Oily fish of the genus Clupea found in the shallow temperate waters of the North Atlantic, the Baltic Sea, the North Within a given species of fish, older and larger fish have higher levels of methylmercury than smaller fish. Fish that develop in water bodies that are more acidic also tend to have higher levels of methylmercury. In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are Methylmercury has a half-life in human blood of about 50 days. Half-Life (computer-game page here It's already listed in the disambiguation page Blood is a specialized Bodily fluid that delivers necessary substances to the body's cells ��such as nutrients and oxygen—and transports Waste products

Biological impact

Ingested methylmercury is readily and completely absorbed by the gastrointestinal tract. Ingestion is the consumption of a substance by an Organism. In Animals it normally is accomplished by taking in the substance through the Mouth into the It is mostly found complexed with free cysteine and with proteins and peptides containing that amino acid. Peptides (from the Greek πεπτίδια, "small digestibles" are short Polymers formed from the linking in a defined order of α- Amino The methylmercuric-cysteinyl complex is recognized by amino acid transporting proteins in the body as methionine, another essential amino acid. Methionine ( abbreviated as Met or M) is an α- Amino acid with the Chemical formula HO2CCH(NH2CH2CH2SCH3 An essential amino acid or indispensable amino acid is an Amino acid that cannot be synthesized de novo by the organism (usually referring to ^[5] Because of this mimicry, it is transported freely throughout the body including across the blood-brain barrier and across the placenta, where it is absorbed by the developing fetus. The blood-brain barrier (BBB is a metabolic or cellular structure in the Central nervous system (CNS that restricts the passage of various chemical substances and microscopic The placenta is an Ephemeral organ present in placental Vertebrates, such as Eutherial Mammals and Sharks during Gestation A fetus (or foetus or fœtus) is a developing Mammal or other Viviparous Vertebrate, after the Embryonic stage and Because of this mimicry and its strong binding to proteins methylmercury is not readily eliminated.

Several studies indicate that methylmercury is linked to subtle developmental deficits in children exposed in-utero such as loss of IQ points, and decreased performance in tests of language skills, memory function and attention deficits. Methylmercury exposure in adults has also been linked to increased risk of cardiovascular disease including heart attack. Cardiovascular disease or cardiovascular diseases refers to the class of diseases that involve the Heart or Blood vessels ( arteries and Myocardial infarction ( MI or AMI for acute myocardial infarction) also known as a heart attack, occurs when the blood supply Some evidence also suggests that methylmercury can cause autoimmune effects in sensitive individuals. Autoimmunity is the failure of an organism to recognize its own constituent parts as self, which results in an immune response against its own cells and tissues However, to date, methylmercury has not been linked to any specific neurologic or autoimmune disease. Although there is no doubt that methylmercury is toxic in several respects, including through exposure of the developing fetus, there is still some controversy as to the levels of methylmercury in the diet that can result in adverse effects.

There have been several episodes in which large numbers of people were severely poisoned by food contaminated with high levels of methylmercury, notably the dumping of industrial waste that resulted in the pollution and subsequent mass poisoning in Minamata and Niigata, Japan^[6] and the situation in Iraq in the 1960s and 1970s in which wheat treated with methylmercury as a preservative and intended as seed grain was fed to animals and directly consumed by people (see Basra poison grain disaster). Industrial waste is a type of waste produced by industrial activity, such as that of factories, mills and mines. sometimes referred to as, is a neurological syndrome caused by severe Mercury poisoning. is a city located in Kumamoto prefecture, Japan. It is on the west coast of Kyūshū. is the capital and the most populous city of Niigata Prefecture, Japan. For a topic outline on this subject see List of basic Japan topics. For a topic outline on this subject see List of basic Iraq topics. The 1960s decade refers to the years from the beginning of 1960 to the end of 1969 This article is about the Decade 1970-1979 For the Year 1970 see 1970. The Basra poison grain disaster was a mass Methylmercury poisoning incident that originated in September 1971 in the Iraqi port of Basra. These episodes resulted in neurologic symptoms including paresthesias, loss of physical coordination, difficulty in speech, narrowing of the visual field, hearing impairment, blindness, and death. A symptom' (from Greek σύμπτωμα, "accident misfortune that which befalls" from συμπίπτω, "I befall" from Paresthesia (pron /ˌpɛɹɪsˈθiʒə/ paraesthesia in British English, pron Dysarthria is a motor Speech disorder resulting from neurological injury, characterised by poor articulation (cf The term visual field is sometimes used as a Synonym to Field of view, though they do not designate the same thing Blindness is the condition of lacking Visual perception due to Physiological or Neurological factors Children who had been exposed in-utero through their mothers' ingestion were also affected with a range of symptoms including motor difficulties, sensory problems and mental retardation. Mental retardation is a generalized triarchic disorder characterized by subaverage cognitive functioning and deficits in two or more adaptive behaviors with onset before the age

At present, exposures of this magnitude are rarely seen and are confined to isolated incidents. Accordingly, concern over methylmercury pollution is currently focused on more subtle effects that may be linked to levels of exposure presently seen in populations with high to moderate levels of dietary fish consumption. These effects are not necessarily identifiable on an individual level or may not be uniquely recognizable as due to methylmercury. However, such effects may be detected by comparing populations with different levels of exposure.

Many governmental agencies, notably the United States Environmental Protection Agency (EPA), the United States Food and Drug Administration (FDA), Health Canada and the European Union Health and Consumer Protection Directorate-General as well as the World Health Organization (WHO) and the United Nations Food and Agriculture Organization (FAO) have issued guidance for fish consumers that is designed to limit methylmercury exposure from fish consumption. Health Canada ( French: Santé Canada) is the department of the government of Canada with responsibility for national Public health At present, most of this guidance is based on protection of the developing fetus, however, future guidance may also address cardiovascular risk. In general, fish consumption advice attempts to convey the message that fish is a good source of nutrition and has significant health benefits, but that consumers, particularly pregnant women, women planning to become pregnant, nursing mothers and young children, should avoid fish with high levels of methylmercury, limit their intake of fish with moderate levels of methylmercury, and consume fish with low levels of methylmercury no more than twice a week. ^[7][8]

See also

• Dimethylmercury, same with another methyl group
• ethylmercury related compound
• Mercury poisoning
• Minamata disease

References

1. ^ Govindaswamy, N. Dimethylmercury (( C[[Hydrogen H]]32 Hg) is a flammable colorless liquid and one of the strongest known Neurotoxins It is described In Chemistry, a methyl group is a Hydrophobic Alkyl Functional group named after Methane (4 Ethylmercury (sometimes ethyl mercury) is a Cation composed of an Ethyl group and a mercury atom its chemical formula is C 2 Mercury poisoning (also known as mercurialism, hydrargyria, Hunter-Russell syndrome, or acrodynia when affecting children is a Disease sometimes referred to as, is a neurological syndrome caused by severe Mercury poisoning. ; J. Moy & M. Millar et al. (1992), Inorg. Chem. 26: 5343
2. ^ Erni, I. & G. Geier (1979), Helv. Chim. Acta 62: 1007
3. ^ Tewalt, S. J. ; L. J. Bragg & R. B. Finkelman (2005), "Mercury in U.S. coal -- Abundance, distribution, and modes of occurrence", Fact Sheet 095-01 (Online Version 1. 0 ed. ), U. S. Geological Survey, <http://pubs.usgs.gov/fs/fs095-01/>. Retrieved on January 12, 2006
4. ^ Burros, Marian (2008-01-23), “High Mercury Levels Are Found in Tuna Sushi”, The New York Times, <http://www.nytimes.com/2008/01/23/dining/23sushi.html> 
5. ^ Kerper, L. Events 475 - Basiliscus becomes Byzantine Emperor, with a coronation ceremony in the Hebdomon palace in Constantinople Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 393 - Roman Emperor Theodosius I proclaims his nine year old son Honorius co-emperor E. ; N. Ballatori & T. W. Clarkson (1992), "Methylmercury transport across the blood-brain barrier by an amino acid carrier", Am. J. Physiol. 262 (5 Pt. 2): R761–R765, <http://ajpregu.physiology.org/cgi/content/abstract/262/5/R761>
6. ^ Myers, G. J. ; P. W. Davidson & B. Weiss (2004), "Methyl mercury exposure and poisoning at Niigata, Japan", SMDJ Seychelles Medical and Dental Journal 7 (Special Issue): 132–133, <http://www.seychelles.net/smdj/SECVA.pdf>. Retrieved on January 12, 2006
7. ^ Information on characteristic levels of methylmercury by species can be found at http://www.cfsan.fda.gov/~frf/sea-mehg.html
8. ^ a wallet-card guide for consumers can be found at http://www.nrdc.org/health/effects/mercury/protect.asp

External links

• ATSDR - ToxFAQs: Mercury
• ATSDR - Public Health Statement: Mercury
• ATSDR - ALERT! Patterns of Metallic Mercury Exposure, 6/26/97
• ATSDR - MMG: Mercury
• ATSDR - Toxicological Profile: Mercury
• National Pollutant Inventory - Mercury and compounds Fact Sheet
• Methylmercury-in-fish exposure calculator provided by GotMercury.Org, which uses FDA mercury data with the EPA's calculated safe exposure levels.
• Methylmercury Contamination in Fish and Shellfish
• nytimes.com, Tuna Fish Stories: The Candidates Spin the Sushi