MERCURY is a chemical element with symbol HG and atomic number 80. It is commonly known as QUICKSILVER and was formerly named HYDRARGYRUM (/haɪˈdrɑːrdʒərəm/ ). A heavy , silvery d-block element, mercury is the only metallic element that is liquid at standard conditions for temperature and pressure ; the only other element that is liquid under these conditions is bromine , though metals such as caesium , gallium , and rubidium melt just above room temperature .
Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide ). The red pigment vermilion is obtained by grinding natural cinnabar or synthetic mercuric sulfide.
Mercury is used in thermometers , barometers , manometers , sphygmomanometers , float valves , mercury switches , mercury relays , fluorescent lamps and other devices, though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alternatives such as alcohol - or galinstan -filled glass thermometers and thermistor - or infrared -based electronic instruments. Likewise, mechanical pressure gauges and electronic strain gauge sensors have replaced mercury sphygmomanometers. Mercury remains in use in scientific research applications and in amalgam for dental restoration in some locales. It is used in fluorescent lighting . Electricity passed through mercury vapor in a fluorescent lamp produces short-wave ultraviolet light which then causes the phosphor in the tube to fluoresce , making visible light.
Mercury poisoning can result from exposure to water-soluble forms of mercury (such as mercuric chloride or methylmercury ), by inhalation of mercury vapor, or by ingesting any form of mercury.
* 1 Properties
* 1.1 Physical properties
* 1.2 Chemical properties
* 1.2.1 Amalgams
* 1.3 Isotopes
* 2 Etymology * 3 History * 4 Occurrence
* 5 Chemistry
* 5.1 Compounds of mercury(I) * 5.2 Compounds of mercury(II) * 5.3 Possibility of higher oxidation states * 5.4 Organomercury compounds
* 6 Applications
* 6.1 Medicine * 6.2 Production of chlorine and caustic soda * 6.3 Laboratory uses
* 6.4 Niche uses
* 6.4.1 Cosmetics
* 6.5 Firearms
* 6.6 Historic uses
* 6.6.1 Historic medicinal uses
* 7 Toxicity and safety
* 7.1 Releases in the environment * 7.2 Sediment contamination
* 7.3 Occupational exposure
* 7.3.1 Effects and symptoms of mercury poisoning * 7.3.2 Treatment
* 8 Regulations
* 9 See also * 10 References * 11 Further reading * 12 External links
A pound coin (density ~7.6 g/cm3) floats in mercury due to the combination of the buoyant force and surface tension .
Mercury is a heavy, silvery-white liquid metal. Compared to other metals, it is a poor conductor of heat, but a fair conductor of electricity.
It has a freezing point of −38.83 °C and a boiling point of 356.73 °C, both the lowest of any metal. Upon freezing, the volume of mercury decreases by 3.59% and its density changes from 13.69 g/cm3 when liquid to 14.184 g/cm3 when solid. The coefficient of volume expansion is 181.59 × 10−6 at 0 °C, 181.71 × 10−6 at 20 °C and 182.50 × 10−6 at 100 °C (per °C). Solid mercury is malleable and ductile and can be cut with a knife.
A complete explanation of mercury's extreme volatility delves deep into the realm of quantum physics , but it can be summarized as follows: mercury has a unique electron configuration where electrons fill up all the available 1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d, 4f, 5s, 5p, 5d, and 6s subshells . Because this configuration strongly resists removal of an electron, mercury behaves similarly to noble gases , which form weak bonds and hence melt at low temperatures.
The stability of the 6s shell is due to the presence of a filled 4f shell. An f shell poorly screens the nuclear charge that increases the attractive Coulomb interaction of the 6s shell and the nucleus (see lanthanide contraction ). The absence of a filled inner f shell is the reason for the somewhat higher melting temperature of cadmium and zinc , although both these metals still melt easily and, in addition, have unusually low boiling points.
Mercury does not react with most acids, such as dilute sulfuric acid , although oxidizing acids such as concentrated sulfuric acid and nitric acid or aqua regia dissolve it to give sulfate , nitrate , and chloride . Like silver, mercury reacts with atmospheric hydrogen sulfide . Mercury reacts with solid sulfur flakes, which are used in mercury spill kits to absorb mercury (spill kits also use activated carbon and powdered zinc).
Mercury-discharge spectral calibration lamp
Mercury dissolves many other metals such as gold and silver to form
Mercury readily combines with aluminium to form a mercury-aluminium amalgam when the two pure metals come into contact. Since the amalgam destroys the aluminium oxide layer which protects metallic aluminium from oxidizing in-depth (as in iron rusting ), even small amounts of mercury can seriously corrode aluminium. For this reason, mercury is not allowed aboard an aircraft under most circumstances because of the risk of it forming an amalgam with exposed aluminium parts in the aircraft.
Mercury embrittlement is the most common type of liquid metal embrittlement.
Main article: Isotopes of mercury
There are seven stable isotopes of mercury with 202 Hg being the most abundant (29.86%). The longest-lived radioisotopes are 194 Hg with a half-life of 444 years, and 203 Hg with a half-life of 46.612 days. Most of the remaining radioisotopes have half-lives that are less than a day. 199 Hg and 201 Hg are the most often studied NMR -active nuclei, having spins of 1⁄2 and 3⁄2 respectively.
Hg is the modern chemical symbol for mercury. It comes from hydrargyrum, a Latinized form of the Greek word ὑδράργυρος (hydrargyros), which is a compound word meaning "water-silver" (from ὑδρ- hydr-, the root of ὕδωρ, "water," and ἄργυρος argyros "silver") – since it is liquid like water and shiny like silver. The element was named after the Roman god Mercury , known for his speed and mobility. It is associated with the planet Mercury ; the astrological symbol for the planet is also one of the alchemical symbols for the metal; the Sanskrit word for alchemy is Rasavātam which means "the way of mercury". Mercury is the only metal for which the alchemical planetary name became the common name.
The symbol for the planet Mercury (☿) has been used since ancient times to represent the element
Mercury was found in Egyptian tombs that date from 1500 BC.
In November 2014 "large quantities" of mercury were discovered in a chamber 60 feet below the 1800-year-old pyramid known as the "Temple of the Feathered Serpent ," "the third largest pyramid of Teotihuacan ," Mexico along with "jade statues, jaguar remains, a box filled with carved shells and rubber balls."
The ancient Greeks used cinnabar (mercury sulfide) in ointments; the
ancient Egyptians and the Romans used it in cosmetics . In
once a major city of the
Maya civilization , a pool of mercury was
found under a marker in a
Mesoamerican ballcourt . By 500 BC mercury
was used to make amalgams (Medieval
Alchemists thought of mercury as the First Matter from which all metals were formed. They believed that different metals could be produced by varying the quality and quantity of sulfur contained within the mercury. The purest of these was gold, and mercury was called for in attempts at the transmutation of base (or impure) metals into gold, which was the goal of many alchemists.
The mines in
See also: Category:Mercury minerals and Category:Mercury mines
Mercury is an extremely rare element in Earth's crust , having an average crustal abundance by mass of only 0.08 parts per million (ppm). Because it does not blend geochemically with those elements that constitute the majority of the crustal mass, mercury ores can be extraordinarily concentrated considering the element's abundance in ordinary rock. The richest mercury ores contain up to 2.5% mercury by mass, and even the leanest concentrated deposits are at least 0.1% mercury (12,000 times average crustal abundance). It is found either as a native metal (rare) or in cinnabar , corderoite , livingstonite and other minerals , with cinnabar (HgS) being the most common ore. Mercury ores usually occur in very young orogenic belts where rocks of high density are forced to the crust of Earth, often in hot springs or other volcanic regions.
Beginning in 1558, with the invention of the patio process to extract
silver from ore using mercury, mercury became an essential resource in
the economy of Spain and its American colonies. Mercury was used to
extract silver from the lucrative mines in
New Spain and
Former mines in Italy, the United States and Mexico, which once
produced a large proportion of the world supply, have now been
completely mined out or, in the case of Slovenia (
Mercury is extracted by heating cinnabar in a current of air and condensing the vapor. The equation for this extraction is HgS + O2 → Hg + SO2
Because of the high toxicity of mercury, both the mining of cinnabar and refining for mercury are hazardous and historic causes of mercury poisoning. In China, prison labor was used by a private mining company as recently as the 1950s to develop new cinnabar mines. Thousands of prisoners were used by the Luo Xi mining company to establish new tunnels. Worker health in functioning mines is at high risk.
European Union directive calling for compact fluorescent bulbs to
be made mandatory by 2012 has encouraged
Abandoned mercury mine processing sites often contain very hazardous waste piles of roasted cinnabar calcines . Water run-off from such sites is a recognized source of ecological damage. Former mercury mines may be suited for constructive re-use. For example, in 1976 Santa Clara County, California purchased the historic Almaden Quicksilver Mine and created a county park on the site, after conducting extensive safety and environmental analysis of the property.
See also: Category:Mercury compounds
Mercury exists in two main oxidation states, I and II.
COMPOUNDS OF MERCURY(I)
Unlike its lighter neighbors, cadmium and zinc, mercury usually forms simple stable compounds with metal-metal bonds. Most mercury(I) compounds are diamagnetic and feature the dimeric cation, Hg2+ 2. Stable derivatives include the chloride and nitrate. Treatment of Hg(I) compounds complexation with strong ligands such as sulfide, cyanide, etc. induces disproportionation to Hg2+ and elemental mercury. Mercury(I) chloride , a colorless solid also known as calomel , is really the compound with the formula Hg2Cl2, with the connectivity Cl-Hg-Hg-Cl. It is a standard in electrochemistry. It reacts with chlorine to give mercuric chloride, which resists further oxidation. Mercury(I) hydride , a colorless gas, has the formula HgH, containing no Hg-Hg bond.
Indicative of its tendency to bond to itself, mercury forms mercury polycations , which consist of linear chains of mercury centers, capped with a positive charge. One example is Hg2+ 3(AsF− 6) 2.
COMPOUNDS OF MERCURY(II)
Mercury(II) is the most common oxidation state and is the main one in nature as well. All four mercuric halides are known. They form tetrahedral complexes with other ligands but the halides adopt linear coordination geometry, somewhat like Ag+ does. Best known is mercury(II) chloride , an easily sublimating white solid. HgCl2 forms coordination complexes that are typically tetrahedral, e.g. HgCl2− 4.
Mercury(II) oxide , the main oxide of mercury, arises when the metal is exposed to air for long periods at elevated temperatures. It reverts to the elements upon heating near 400 °C, as was demonstrated by Joseph Priestley in an early synthesis of pure oxygen . Hydroxides of mercury are poorly characterized, as they are for its neighbors gold and silver.
Being a soft metal , mercury forms very stable derivatives with the heavier chalcogens. Preeminent is mercury(II) sulfide , HgS, which occurs in nature as the ore cinnabar and is the brilliant pigment vermillion . Like ZnS, HgS crystallizes in two forms , the reddish cubic form and the black zinc blende form. Mercury(II) selenide (HgSe) and mercury(II) telluride (HgTe) are also known, these as well as various derivatives, e.g. mercury cadmium telluride and mercury zinc telluride being semiconductors useful as infrared detector materials.
Mercury(II) salts form a variety of complex derivatives with ammonia . These include Millon's base (Hg2N+), the one-dimensional polymer (salts of HgNH+ 2) n), and "fusible white precipitate" or Cl2. Known as Nessler\'s reagent , potassium tetraiodomercurate(II) (HgI2− 4) is still occasionally used to test for ammonia owing to its tendency to form the deeply colored iodide salt of Millon's base.
Mercury fulminate is a detonator widely used in explosives .
POSSIBILITY OF HIGHER OXIDATION STATES
Oxidation states above +2 in an uncharged species are extremely rare, although a cyclic mercurinium(IV) cation, with three substituents, may be an intermediate in oxymercuration reactions. In 2007, a report of synthesis of a mercury(IV) compound, mercury(IV) fluoride , was published, but later experiments could not replicate the synthesis. In the 1970s, there was a claim on synthesis of a mercury(III) compound, but it is now thought to be false.
Main article: Organomercury compound
Organic mercury compounds are historically important but are of
little industrial value in the western world. Mercury(II) salts are a
rare example of simple metal complexes that react directly with
Organomercury compounds are always divalent and
usually two-coordinate and linear geometry. Unlike organocadmium and
organozinc compounds, organomercury compounds do not react with water.
They usually have the formula HgR2, which are often volatile, or HgRX,
which are often solids, where R is aryl or alkyl and X is usually
halide or acetate.
The bulb of a mercury-in-glass thermometer
Mercury is used primarily for the manufacture of industrial chemicals or for electrical and electronic applications. It is used in some thermometers, especially ones which are used to measure high temperatures. A still increasing amount is used as gaseous mercury in fluorescent lamps , while most of the other applications are slowly phased out due to health and safety regulations and is in some applications replaced with less toxic but considerably more expensive Galinstan alloy .
See also: Amalgam (dentistry) Amalgam filling
Mercury and its compounds have been used in medicine, although they are much less common today than they once were, now that the toxic effects of mercury and its compounds are more widely understood. The first edition of the Merck's Manual featured many mercuric compounds such as:
* Mercauro * Mercuro-iodo-hemol. * Mercury-ammonium chloride * Mercury Benzoate * Mercuric * Mercury Bichloride (Corrosive Mercuric Chloride, U.S.P.) * Mercury Chloride * Mild Mercury Cyanide * Mercury Succinimide * Mercury Iodide * Red Mercury Biniodide * Mercury Iodide * Yellow Mercury Proto-iodide * Black (Hahnemann), Soluble Mercury Oxide * Red Mercury Oxide * Yellow Mercury Oxide * Mercury Salicylate * Mercury Succinimide * Mercury Imido-succinate * Mercury Sulphate * Basic Mercury Subsulphate; Turpeth Mineral * Mercury Tannate * Mercury-Ammonium Chloride
Mercury is an ingredient in dental amalgams . Thiomersal (called Thimerosal in the United States) is an organic compound used as a preservative in vaccines , though this use is in decline. Thiomersal is metabolized to ethyl mercury . Although it was widely speculated that this mercury-based preservative could cause or trigger autism in children, scientific studies showed no evidence supporting any such link. Nevertheless, thiomersal has been removed from, or reduced to trace amounts in all U.S. vaccines recommended for children 6 years of age and under, with the exception of inactivated influenza vaccine.
Another mercury compound, merbromin (Mercurochrome), is a topical antiseptic used for minor cuts and scrapes that is still in use in some countries.
Mercury in the form of one of its common ores, cinnabar, is used in various traditional medicines, especially in traditional Chinese medicine . Review of its safety has found that cinnabar can lead to significant mercury intoxication when heated, consumed in overdose , or taken long term, and can have adverse effects at therapeutic doses, though effects from therapeutic doses are typically reversible. Although this form of mercury appears to be less toxic than other forms, its use in traditional Chinese medicine has not yet been justified, as the therapeutic basis for the use of cinnabar is not clear.
Today, the use of mercury in medicine has greatly declined in all
respects, especially in developed countries. Thermometers and
sphygmomanometers containing mercury were invented in the early 18th
and late 19th centuries, respectively. In the early 21st century,
their use is declining and has been banned in some countries, states
and medical institutions. In 2002, the
U.S. Senate passed legislation
to phase out the sale of non-prescription mercury thermometers. In
2003, Washington and
PRODUCTION OF CHLORINE AND CAUSTIC SODA
Some medical thermometers , especially those for high temperatures, are filled with mercury; they are gradually disappearing. In the United States, non-prescription sale of mercury fever thermometers has been banned since 2003.
Mercury is also found in liquid mirror telescopes .
Some transit telescopes use a basin of mercury to form a flat and absolutely horizontal mirror, useful in determining an absolute vertical or perpendicular reference. Concave horizontal parabolic mirrors may be formed by rotating liquid mercury on a disk, the parabolic form of the liquid thus formed reflecting and focusing incident light. Such telescopes are cheaper than conventional large mirror telescopes by up to a factor of 100, but the mirror cannot be tilted and always points straight up.
Liquid mercury is a part of popular secondary reference electrode (called the calomel electrode ) in electrochemistry as an alternative to the standard hydrogen electrode . The calomel electrode is used to work out the electrode potential of half cells . Last, but not least, the triple point of mercury, −38.8344 °C, is a fixed point used as a temperature standard for the International Temperature Scale (ITS-90 ).
In polarography both the dropping mercury electrode and the hanging mercury drop electrode use elemental mercury. This use allows a new uncontaminated electrode to be available for each measurement or each new experiment.
Gaseous mercury is used in mercury-vapor lamps and some "neon sign " type advertising signs and fluorescent lamps . Those low-pressure lamps emit very spectrally narrow lines, which are traditionally used in optical spectroscopy for calibration of spectral position. Commercial calibration lamps are sold for this purpose; reflecting a fluorescent ceiling light into a spectrometer is a common calibration practice. Gaseous mercury is also found in some electron tubes , including ignitrons , thyratrons , and mercury arc rectifiers . It is also used in specialist medical care lamps for skin tanning and disinfection. Gaseous mercury is added to cold cathode argon -filled lamps to increase the ionization and electrical conductivity . An argon-filled lamp without mercury will have dull spots and will fail to light correctly. Lighting containing mercury can be bombarded /oven pumped only once. When added to neon filled tubes the light produced will be inconsistent red/blue spots until the initial burning-in process is completed; eventually it will light a consistent dull off-blue color.
The deep violet glow of a mercury vapor discharge in a germicidal lamp , whose spectrum is rich in invisible ultraviolet radiation. *
Skin tanner containing a low-pressure mercury vapor lamp and two infrared lamps, which act both as light source and electrical ballast *
Assorted types of fluorescent lamps.
Mercury, as thiomersal , is widely used in the manufacture of mascara . In 2008, Minnesota became the first state in the United States to ban intentionally added mercury in cosmetics, giving it a tougher standard than the federal government.
A study in geometric mean urine mercury concentration identified a
previously unrecognized source of exposure (skin care products) to
inorganic mercury among
New York City
A Single-Pole, Single-Throw (SPST) mercury switch. Mercury manometer to measure pressure
Many historic applications made use of the peculiar physical properties of mercury, especially as a dense liquid and a liquid metal:
* Quantities of liquid mercury ranging from 90 to 600 grams (3.2 to
21.2 oz) have been recovered from elite Maya tombs (100-700AD) or
ritual caches at six sites. This mercury may have been used in bowls
as mirrors for divinatory purposes. Five of these date to the Classic
Maya civilization (c. 250–900) but one example predated
Others applications made use of the chemical properties of mercury:
* The mercury battery is a non-rechargeable electrochemical battery
, a primary cell , that was common in the middle of the 20th century.
It was used in a wide variety of applications and was available in
various sizes, particularly button sizes. Its constant voltage output
and long shelf life gave it a niche use for camera light meters and
hearing aids. The mercury cell was effectively banned in most
countries in the 1990s due to concerns about the mercury contaminating
* Mercury was used for preserving wood, developing daguerreotypes ,
silvering mirrors , anti-fouling paints (discontinued in 1990),
herbicides (discontinued in 1995), handheld maze games, cleaning, and
road leveling devices in cars. Mercury compounds have been used in
antiseptics , laxatives, antidepressants , and in antisyphilitics .
* It was allegedly used by allied spies to sabotage Luftwaffe
planes: a mercury paste was applied to bare aluminium , causing the
metal to rapidly corrode ; this would cause structural failures.
Chloralkali process : The largest industrial use of mercury during
the 20th century was in electrolysis for separating chlorine and
sodium from brine; mercury being the anode of the Castner-Kellner
process . The chlorine was used for bleaching paper (hence the
location of many of these plants near paper mills) while the sodium
was used to make sodium hydroxide for soaps and other cleaning
products. This usage has largely been discontinued, replaced with
other technologies that utilize membrane cells.
* As electrodes in some types of electrolysis , batteries (mercury
cells ), sodium hydroxide and chlorine production, handheld games,
catalysts , insecticides .
* Mercury was once used as a gun barrel bore cleaner.
* From the mid-18th to the mid-19th centuries, a process called
"carroting " was used in the making of felt hats. Animal skins were
rinsed in an orange solution (the term "carroting" arose from this
color) of the mercury compound mercuric nitrate , Hg(NO3)2·2H2O.
This process separated the fur from the pelt and matted it together.
This solution and the vapors it produced were highly toxic. The United
States Public Health Service banned the use of mercury in the felt
industry in December 1941. The psychological symptoms associated with
mercury poisoning inspired the phrase "mad as a hatter ". Lewis
Carroll 's "
Mad Hatter " in his book Alice\'s Adventures in Wonderland
was a play on words based on the older phrase, but the character
himself does not exhibit symptoms of mercury poisoning.
Historic Medicinal Uses
Mercury(I) chloride (also known as calomel or mercurous chloride) has been used in traditional medicine as a diuretic , topical disinfectant , and laxative . Mercury(II) chloride (also known as mercuric chloride or corrosive sublimate) was once used to treat syphilis (along with other mercury compounds), although it is so toxic that sometimes the symptoms of its toxicity were confused with those of the syphilis it was believed to treat. It is also used as a disinfectant. Blue mass , a pill or syrup in which mercury is the main ingredient, was prescribed throughout the 19th century for numerous conditions including constipation, depression, child-bearing and toothaches. In the early 20th century, mercury was administered to children yearly as a laxative and dewormer, and it was used in teething powders for infants. The mercury-containing organohalide merbromin (sometimes sold as Mercurochrome) is still widely used but has been banned in some countries such as the U.S.
TOXICITY AND SAFETY
Mercury and most of its compounds are extremely toxic and must be handled with care; in cases of spills involving mercury (such as from certain thermometers or fluorescent light bulbs ), specific cleaning procedures are used to avoid exposure and contain the spill. Protocols call for physically merging smaller droplets on hard surfaces, combining them into a single larger pool for easier removal with an eyedropper , or for gently pushing the spill into a disposable container. Vacuum cleaners and brooms cause greater dispersal of the mercury and should not be used. Afterwards, fine sulfur , zinc , or some other powder that readily forms an amalgam (alloy) with mercury at ordinary temperatures is sprinkled over the area before itself being collected and properly disposed of. Cleaning porous surfaces and clothing is not effective at removing all traces of mercury and it is therefore advised to discard these kinds of items should they be exposed to a mercury spill.
Mercury can be absorbed through the skin and mucous membranes and mercury vapors can be inhaled, so containers of mercury are securely sealed to avoid spills and evaporation. Heating of mercury, or of compounds of mercury that may decompose when heated, should be carried out with adequate ventilation in order to minimize exposure to mercury vapor. The most toxic forms of mercury are its organic compounds , such as dimethylmercury and methylmercury . Mercury can cause both chronic and acute poisoning.
RELEASES IN THE ENVIRONMENT
Amount of atmospheric mercury deposited at Wyoming's Upper Fremont Glacier over the last 270 years
Preindustrial deposition rates of mercury from the atmosphere may be about 4 ng /(1 L of ice deposit). Although that can be considered a natural level of exposure, regional or global sources have significant effects. Volcanic eruptions can increase the atmospheric source by 4–6 times.
Natural sources, such as volcanoes , are responsible for approximately half of atmospheric mercury emissions. The human-generated half can be divided into the following estimated percentages:
* 65% from stationary combustion, of which coal-fired power plants are the largest aggregate source (40% of U.S. mercury emissions in 1999). This includes power plants fueled with gas where the mercury has not been removed. Emissions from coal combustion are between one and two orders of magnitude higher than emissions from oil combustion, depending on the country. * 11% from gold production. The three largest point sources for mercury emissions in the U.S. are the three largest gold mines. Hydrogeochemical release of mercury from gold-mine tailings has been accounted as a significant source of atmospheric mercury in eastern Canada. * 6.8% from non-ferrous metal production, typically smelters . * 6.4% from cement production. * 3.0% from waste disposal , including municipal and hazardous waste , crematoria , and sewage sludge incineration. * 3.0% from caustic soda production. * 1.4% from pig iron and steel production. * 1.1% from mercury production, mainly for batteries. * 2.0% from other sources.
The above percentages are estimates of the global human-caused mercury emissions in 2000, excluding biomass burning, an important source in some regions.
Recent atmospheric mercury contamination in outdoor urban air was measured at 0.01–0.02 µg/m3. A 2001 study measured mercury levels in 12 indoor sites chosen to represent a cross-section of building types, locations and ages in the New York area. This study found mercury concentrations significantly elevated over outdoor concentrations, at a range of 0.0065 – 0.523 μg/m3. The average was 0.069 μg/m3.
Mercury also enters into the environment through the improper disposal (e.g., land filling, incineration) of certain products. Products containing mercury include: auto parts, batteries , fluorescent bulbs, medical products, thermometers, and thermostats. Due to health concerns (see below), toxics use reduction efforts are cutting back or eliminating mercury in such products. For example, the amount of mercury sold in thermostats in the United States decreased from 14.5 tons in 2004 to 3.9 tons in 2007.
Most thermometers now use pigmented alcohol instead of mercury, and galinstan alloy thermometers are also an option. Mercury thermometers are still occasionally used in the medical field because they are more accurate than alcohol thermometers, though both are commonly being replaced by electronic thermometers and less commonly by galinstan thermometers. Mercury thermometers are still widely used for certain scientific applications because of their greater accuracy and working range.
Historically, one of the largest releases was from the Colex plant, a lithium-isotope separation plant at Oak Ridge, Tennessee. The plant operated in the 1950s and 1960s. Records are incomplete and unclear, but government commissions have estimated that some two million pounds of mercury are unaccounted for.
A serious industrial disaster was the dumping of mercury compounds into Minamata Bay, Japan. It is estimated that over 3,000 people suffered various deformities, severe mercury poisoning symptoms or death from what became known as Minamata disease .
The tobacco plant readily absorbs and accumulates heavy metals such as mercury from the surrounding soil into its leaves. These are subsequently inhaled during tobacco smoking . While mercury is a constituent of tobacco smoke , studies have largely failed to discover a signiﬁcant correlation between smoking and Hg uptake by humans compared to sources such as occupational exposure, fish consumption, and amalgam tooth ﬁllings .
Sediments within large urban-industrial estuaries act as an important
sink for point source and diffuse mercury pollution within catchments.
A 2015 study of foreshore sediments from the
Due to the health effects of mercury exposure, industrial and commercial uses are regulated in many countries. The World Health Organization , OSHA , and NIOSH all treat mercury as an occupational hazard, and have established specific occupational exposure limits. Environmental releases and disposal of mercury are regulated in the U.S. primarily by the United States Environmental Protection Agency .
Effects And Symptoms Of Mercury Poisoning
Main article: Mercury poisoning
Toxic effects include damage to the brain, kidneys and lungs. Mercury poisoning can result in several diseases, including acrodynia (pink disease), Hunter-Russell syndrome, and Minamata disease .
Symptoms typically include sensory impairment (vision, hearing, speech), disturbed sensation and a lack of coordination. The type and degree of symptoms exhibited depend upon the individual toxin, the dose, and the method and duration of exposure. Case control studies have shown effects such as tremors, impaired cognitive skills, and sleep disturbance in workers with chronic exposure to mercury vapor even at low concentrations in the range 0.7–42 μg/m3. A study has shown that acute exposure (4 – 8 hours) to calculated elemental mercury levels of 1.1 to 44 mg/m3 resulted in chest pain, dyspnea , cough, hemoptysis , impairment of pulmonary function, and evidence of interstitial pneumonitis . Acute exposure to mercury vapor has been shown to result in profound central nervous system effects, including psychotic reactions characterized by delirium, hallucinations, and suicidal tendency. Occupational exposure has resulted in broad-ranging functional disturbance, including erethism , irritability, excitability, excessive shyness, and insomnia. With continuing exposure, a fine tremor develops and may escalate to violent muscular spasms. Tremor initially involves the hands and later spreads to the eyelids, lips, and tongue. Long-term, low-level exposure has been associated with more subtle symptoms of erethism, including fatigue, irritability, loss of memory, vivid dreams and depression.
Research on the treatment of mercury poisoning is limited. Currently available drugs for acute mercurial poisoning include chelators N-acetyl-D, L-penicillamine (NAP), British Anti-Lewisite (BAL), 2,3-dimercapto-1-propanesulfonic acid (DMPS), and dimercaptosuccinic acid (DMSA). In one small study including 11 construction workers exposed to elemental mercury, patients were treated with DMSA and NAP. Chelation therapy with both drugs resulted in the mobilization of a small fraction of the total estimated body mercury. DMSA was able to increase the excretion of mercury to a greater extent than NAP.
Mercury in fish
In the United States, the Environmental Protection Agency is charged with regulating and managing mercury contamination. Several laws give the EPA this authority, including the Clean Air Act , the Clean Water Act , the Resource Conservation and Recovery Act , and the Safe Drinking Water Act . Additionally, the Mercury-Containing and Rechargeable Battery Management Act , passed in 1996, phases out the use of mercury in batteries, and provides for the efficient and cost-effective disposal of many types of used batteries. North America contributed approximately 11% of the total global anthropogenic mercury emissions in 1995.
The United States Clean Air Act , passed in 1990, put mercury on a list of toxic pollutants that need to be controlled to the greatest possible extent. Thus, industries that release high concentrations of mercury into the environment agreed to install maximum achievable control technologies (MACT). In March 2005, the EPA promulgated a regulation that added power plants to the list of sources that should be controlled and instituted a national cap and trade system. States were given until November 2006 to impose stricter controls, but after a legal challenge from several states, the regulations were struck down by a federal appeals court on 8 February 2008. The rule was deemed not sufficient to protect the health of persons living near coal-fired power plants, given the negative effects documented in the EPA Study Report to Congress of 1998. However newer data published in 2015 showed that after introduction of the stricter controls mercury declined sharply, indicating that the Clean Air Act had its intended impact.
The EPA announced new rules for coal-fired power plants on 22
In the European Union , the directive on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment (see RoHS ) bans mercury from certain electrical and electronic products, and limits the amount of mercury in other products to less than 1000 ppm . There are restrictions for mercury concentration in packaging (the limit is 100 ppm for sum of mercury, lead , hexavalent chromium and cadmium ) and batteries (the limit is 5 ppm). In July 2007, the European Union also banned mercury in non-electrical measuring devices, such as thermometers and barometers. The ban applies to new devices only, and contains exemptions for the health care sector and a two-year grace period for manufacturers of barometers.
Products containing mercury were banned in Sweden in 2009.
In 2008, Denmark also banned dental mercury amalgam, except for molar masticating surface fillings in permanent (adult) teeth.
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* Chemistry in its element