Mercury poisoning is a type of metal poisoning due to exposure to mercury. Symptoms depend on the type, dose, method, and duration of exposure. They may include muscle weakness, poor coordination, numbness in the hands and feet, skin rashes, anxiety, memory problems, speech impediment, difficulty hearing, or difficulty seeing. Exposure to high levels of methylmercury is known as Minamata disease. Exposure to methylmercury in children can cause acrodynia (a pink disease) in which the skin becomes pink and peeling. Long-term complications may include kidney problems and decreased intelligence. The effects of low-dose long-term exposure to methylmercury are unclear.
The forms of mercury exposure include metals, steam, salts, and organic compounds. Most exposure comes from eating fish, amalgam-based tooth fillings, or exposure at work. In fish, higher in the food chain generally have higher levels of mercury. More general poisoning can occur as an attempt to end a person's life. Human activities that release mercury to the environment include coal burning and gold mining. Blood, urine, and hair tests for mercury are available but do not relate well to the amount in the body.
Prevention includes eating a low-mercury diet, removing mercury from medical equipment and other, proper mercury disposal, and not further mining mercury. In those with acute poisoning of inorganic mercury salts, chelation with dimercaptosuccinic acid (DMSA) or dimercaptopropane sulfonate (DMPS) appears to improve yield if administered within hours of exposure. Chelation for those with long-term exposure is an unclear benefit. In certain communities that survive fishing, the level of mercury poisoning among children reaches 1.7 per 100.
Video Mercury poisoning
Signs and symptoms
Common symptoms of mercury poisoning include peripheral neuropathy, which appears as paresthesia or itching, burning, pain, or even a sensation resembling a small insect that creeps above or below the skin (formation); discoloration of the skin (pink cheeks, fingertips and toes); swelling; and desquamation (shedding or peeling skin).
Mercury irreversibly inhibits selenium-dependent enzymes (see below) and may also inactivate S -addosyl-methionine, which is needed for catecholamine catabolism by catechol- O -methyl transferase. Due to the body's inability to lower catecholamines (eg epinephrine), a person suffering from mercury poisoning may experience a lot of sweat, tachycardia (persistent faster heart beat than normal), increased saliva, and hypertension (high blood pressure).
The affected child may show red cheeks, nose and lips, hair loss, teeth, and nails, a temporary rash, hypotonia (muscle weakness), and increased sensitivity to light. Other symptoms may include renal dysfunction (eg Fanconi syndrome) or neuropsychiatric symptoms such as emotional lability, memory impairment, or insomnia.
Thus, clinical presentation may resemble pheochromocytoma or Kawasaki disease. Desquamation can occur with severe mercury poisoning obtained by handling mercury elements.
Maps Mercury poisoning
Cause
Fish consumption is by far the most significant source of exposure to mercury-related consumption in humans, although plants and livestock also contain mercury due to mercury bioconcentration from seawater, freshwater, marine and lacustrine, soil, and atmospheric sediments, and because biomagnification by ingesting organisms contains other mercury. Mercury exposure may occur from contaminated air pollution, from eating foods that have obtained mercury residues during processing, from exposure to mercury vapor in mercury amalgam dental restorations, and from improper use or disposal of mercury and mercury-containing substances, for example, after an elemental mercury spill or inappropriate discharge of fluorescent lamps.
All of this, except the liquid mercury element produces toxicity or death with less than one gram. The oxidation status of zero mercury (Hg 0 ) exists as steam or as a liquid metal, its windy state (Hg ) exists as inorganic salt, and mercury conditions (Hg 2 ) can form inorganic salts or organomercury compounds.
The consumption of whale and dolphin meat, as is the practice in Japan, is a source of high levels of mercury poisoning. Tetsuya Endo, a professor at Hokkaido University of Health Sciences, has tested whale meat purchased in the Taiji whaling town and found a mercury level of more than 20 times acceptable Japanese standards.
Human-generated sources, such as coal-fired power plants, emit about half of atmospheric mercury, with natural sources like the volcano responsible for the rest. It is estimated that two-thirds of man-made mercury comes from stationary combustion, mostly from coal. Other important sources produced by humans include gold production, nonferrous metal production, cement production, waste disposal, human crematorium, caustic soda production, crude iron and steel production, mercury production (mostly for batteries), and biomass burning.
Workers operating a small independent gold mine are at high risk of mercury poisoning due to the raw processing method. Such is the danger for galamsey in Ghana and a similar worker known as orpailleurs in neighboring francophone countries. Although no official government estimates of the workforce have been made, observers believe 20,000-50,000 work as galamseys in Ghana, a figure including many women, who work as porters. Similar problems have been reported among gold miners in Indonesia.
Mercury and many of its chemical compounds, especially organomercury compounds, can also be easily absorbed through direct contact with naked, or in some cases (such as methylmercury) not adequately protected, skin. Mercury and its compounds are commonly used in chemical laboratories, hospitals, dental clinics, and facilities involved in the production of items such as fluorescent light bulbs, batteries, and explosives.
Many traditional medicines, including Ayurvedic medicines and traditional Chinese medicines contain mercury and other heavy metals.
No scientific data supports the claim that mercury compounds in vaccine preservatives cause autism or its symptoms.
Source
Mercury compounds tend to be much more toxic than elemental or salt shapes. These compounds have been implicated in causing brain and liver damage. The most dangerous mercury compounds, dimethylmercury, are so toxic that even a few microliters spill on the skin, or even on latex gloves, can cause death.
Methylmercury is the main source of organic mercury for all individuals. Because bioaccumulation works through the food network and thus biomagnifies, resulting in high concentrations among populations of several species. Top predator fish, such as tuna or swordfish, are usually more apprehensive than smaller species. The US FDA and EPA recommend women of childbearing age, breastfeeding mothers, and small children to completely avoid swordfish, shark, king mackerel and tilefish from the Gulf of Mexico, and to limit the consumption of albacore tuna ("white") to no more than 6 oz (170 g) per week, and all other fish and shellfish are not more than 12 oz (340 g) per week. A 2006 review of the risks and benefits of fish consumption found, for adults, the benefits of one to two servings of fish per week outweigh the risks, even (except for some fish species) for women of childbearing age, and that avoidance of fish consumption can lead to excess mortality of coronary heart disease and suboptimal nerve development in children.
Period between exposure to methylmercury and the appearance of symptoms in cases of long adult poisoning. The longest recorded recorded period is five months after a single exposure, in the case of Dartmouth (see History); other latent periods in the weeks to months range have also been reported. No explanation for this long latent period is known. When the first symptoms appear, usually paresthesia (tingling or numbness in the skin), it is followed rapidly by a more severe effect, sometimes ending in coma and death. Toxic damage appears to be determined by the mercury peak value, not the length of the exposure.
Exposure to methylmercury during rat pregnancy, a developmental period that roughly models neural development during the first two trimesters of pregnancy, has long-term behavioral consequences that arise in adulthood and, in some cases, may not appear until aging. Neurotransmission of prefrontal cortex or dopamine can be very sensitive to exposure to fine gestational methylmercury and suggests that public health assessment of methylmercury based on intellectual performance may underestimate the impact of methylmercury in public health.
Ethylmercury is a breakthrough product of antibacterial agent of ethylmercurithiosalicylate, which has been used as a topical antiseptic and vaccine preservative (discussed further under Thiomersal below). Its characteristics have not been studied extensively as methylmercury does. It is cleaned of blood much faster, with a half-life of seven to 10 days, and it is metabolized much faster than methylmercury. It is thought to have no methylmercury ability to cross the blood-brain barrier via a transporter, but depends on simple diffusion to enter the brain. Other organic mercury exposure sources include phenylmercuric acetate and phenylmercuric nitrate. These compounds were used in indoor latex paints for their antimildew properties, but were removed in 1990 due to toxicity cases.
Inorganic mercury compounds
Mercury occurs as salts such as mercuric chloride (HgCl 2 ) and mercurous chloride (Hg 2 Cl 2 ), the latter also known as calomel. Because they are more soluble in water, mercury salts are usually more toxic than mercury salts. Their higher solubility allows them to be more easily absorbed from the digestive tract. Mercury affects primarily the gastrointestinal tract and kidneys, and can cause severe kidney damage; However, since they can not cross the blood-brain barrier easily, these salts cause minor neurological damage without continuous or severe exposure. Mercuric cyanide (Hg (CN) 2 ) is a toxic mercury compound that has been used in killing, since it contains not only mercury but also cyanide, which causes cyanide poisoning simultaneously. The drug n-acetyl penicillamine has been used to treat mercury poisoning with limited success.
Mercury element
Quicksilver (liquid metallic liquid) is less absorbed by consumption and skin contact. The steam is the most dangerous form. Animal data show less than 0.01% of the digested mercury is absorbed through intact gastrointestinal tract, though it may not be true for individuals suffering from ileus. Systemic toxicity cases of accidental swallowing are rare, and attempted suicide by intravenous injection does not seem to cause systemic toxicity, although it still causes damage by physically blocking the blood vessels in both the injection site and the lungs. Although not quantitatively studied, the physical properties of liquid element mercury limit its absorption through intact skin and given the very low absorption rate of the gastrointestinal tract, skin absorption will not be high. Some mercury vapor is absorbed dermally, but the absorption by this route is only about 1% of the inhaled.
In humans, about 80% of the inhaled mercury vapor is absorbed through the respiratory tract, which enters the circulatory system and is distributed throughout the body. Chronic exposure through inhalation, even at low concentrations in the range 0.7-42? G/m 3 , has been shown in case-control studies to inflict effects such as tremors, cognitive impaired skills, and sleep disorders in workers.
Acute inhalation of high concentrations leads to various cognitive, personality, sensory, and motor disorders. The most prominent symptoms include tremors (initially affecting the hands and sometimes spreading to other parts of the body), emotional lability (characterized by irritation, excessive shyness, loss of confidence, and anxiety), insomnia, memory loss, neuromuscular changes ( weakness, muscle). atrophy, muscle twitching), headache, polyneuropathy (paresthesia, loss of glove-stocking sensors, hyperactive tendon reflexes, induction of sensory and motor nerves slowing), and performance deficits in cognitive function tests.
Mechanism
The toxicity of the source of mercury can be estimated depending on its nature, ie, salt vs. organomercury compound vs. mercury element.
One mechanism of mercury toxicity involves inhibition of an unchangeable selenoenzyme, such as thioredoxin reductase (IC50 = 9 nM). Although it has many functions, thioredoxin reductase restores vitamin C and E, as well as a number of other important antioxidant molecules, returning to their reduced form, enabling them to resist oxidative damage. Because the level of oxygen consumption is very high in brain tissue, the production of reactive oxygen species (ROS) is emphasized in these vital cells, making them highly susceptible to oxidative damage and especially dependent on the antioxidant protection provided by selenoenzymes. High mercury exposures deplete the amount of selenium available for the biosynthesis of thioredoxin reductase and other selenoenzymes that prevent and reverse oxidative damage, which, if severe and prolonged thinning, result in brain cell dysfunction that can ultimately lead to death.
Mercury in various forms is very dangerous for the fetus as an environmental toxin in pregnancy, as well as in infants. Women who have been exposed to mercury in excess intake of dietary selenium during pregnancy are at risk of giving birth to children with serious birth defects. Mercury exposure that exceeds dietary selenium intake in young children can have severe neurological consequences, preventing nerve sheaths from forming well.
Methylmercury exposure causes elevated levels of antibodies delivered to myelin basic protein (MBP), which is involved in myelination of neurons, and glial fibrillary acidic protein (GFAP), which is important for many central nervous system (CNS). This leads to an autoimmmune response to MBP and GFAP and results in nerve myelin degradation and a general decrease in CNS function.
Diagnosis
The diagnosis of elemental or inorganic mercury poisoning involves determining the history of exposure, physical findings, and increased body burden of mercury. Although overall blood mercury concentrations are usually less than 6 g/L, a fish-rich diet may produce a blood-mercury concentration higher than 200 g/L; it is not useful to measure these levels for suspected cases of elemental or inorganic poisoning due to the short half-life of mercury in the blood. If the exposure is chronic, urine levels may be obtained; 24 hour collection is more reliable than a collection of places. It is difficult or impossible to interpret the urine samples of patients undergoing chelation therapy, as the therapy itself increases mercury levels in the sample.
The diagnosis of organic mercury poisoning differs across blood or hair analysis is more reliable than urine mercury levels.
Prevention
Mercury poisoning can be prevented or minimized by eliminating or reducing exposure to mercury and mercury compounds. To that end, many governments and private groups have sought to regulate the use of mercury on a large scale, or to issue advice on its use. For example, exports from EU mercury and some mercury compounds have been banned since March 15, 2010.
The US Environmental Protection Agency (EPA) issued a recommendation in 2004 on mercury exposure in fish and shellfish. The EPA also developed a "Children of the Child" awareness campaign for children and young adults because of the greater impact of mercury exposure on the population.
Mercury mercury clearance
Mercury thermometers and mercury bulbs are not as common as they used to be, and the amount of mercury they contain is unlikely to be a health problem if handled carefully. However, damaged items still require careful cleaning, as mercury can be difficult to collect and it is easy to inadvertently create much larger exposure problems. If available, sulfur powder can be applied to the spill, to create a solid compound that is more easily removed from the surface than liquid mercury.
Treatment
Identifying and eliminating sources of mercury is very important. Decontamination requires removal of clothing, washing skin with soap and water, and dousing the eyes with salt solution as needed.
Chelation therapy
Chelation therapy for acute inorganic mercury poisoning can be done with DMSA, 2,3-dimercapto-1-propanesulfonic acid (DMPS), D -penicillamine (DPCN), or dimercaprol (BAL). Only DMSA is FDA approved for use in children to treat mercury poisoning. However, some studies have found no clear clinical benefit from DMSA treatment for poisoning by mercury vapors. There is no chelator for methylmercury or ethylmercury approved by the FDA; DMSA is most commonly used for severe methylmercury poisoning, because it is orally administered, has fewer side effects, and has been found to be superior to BAL, DPCN, and DMPS. ? -Lipoic acid (ALA) has been shown to protect against acute mercury poisoning in some mammal species when administered immediately after exposure; Appropriate doses are required, since incorrect doses increase toxicity. Although it has been hypothesized that the frequent low dose ALA may have potential as a mercury chelator, studies in rats have been contradictory. Glutathione and N -acetylcysteine ​​(NAC) is recommended by some doctors, but has been shown to increase mercury concentrations in the kidneys and brain.
Chelation therapy can be harmful if given incorrectly. In August 2005, the wrong EDTA (edetate disodium) form used for chelation therapy resulted in hypocalcemia, leading to cardiac arrest that killed five-year-old autistic children.
More
Experimental findings have shown an interaction between selenium and methylmercury, but epidemiological studies have found little evidence that selenium helps protect against the adverse effects of methylmercury.
Prognosis
Some toxic or partial mercury effects may be returned, either through specific therapy or by natural elimination of the metal after exposure has been discontinued. The autopsy findings show half the age of inorganic mercury in the human brain 27.4 years. Severe or prolonged exposure can cause permanent damage, especially to the fetus, infant, and young child. Young syndrome is believed to be a long-term consequence of mercury poisoning in early childhood.
Mercuric chloride can cause cancer because it has caused an increase in some types of tumors in rats and mice, while methyl mercury has caused renal tumors in male rats. EPA has classified mercury chloride and methyl mercury as a possible human carcinogen (ATSDR, EPA)
Detection in biological fluid
Acrodynia infantil (also known as "calomel disease", "polyneuropathy erythredemic", and "pink disease") is a type of mercury poisoning in children characterized by pain and pink changes in the hands and feet. The word comes from Greek, where ???? means end or extremities , and ????? means sick . Acrodynia is mainly produced from calomel in the form of toothpowder and greatly reduced after calomel was removed from most of the tooth powder in 1954.
Acrodynia is difficult to diagnose, "it is most often postulated that the etiology of this syndrome is an idiosyncratic hypersensitivity reaction to mercury because of a lack of correlation with mercury levels, many of the symptoms resemble recognized mercury poisoning."
Medicine
Mercury was once prescribed as a laxative. Many compounds containing mercury were once used in medicine. These include calomel (mercurous chloride), and mercuric chloride.
Thiomersal
In 1999, the Centers for Disease Control (CDC) and the American Academy of Pediatrics (AAP) asked vaccine makers to remove thiomersal organomersur compounds (spelled "thimerosal" in the US) from the vaccine as quickly as possible, and thiomersal was phased out. of the US and European vaccines, except for some influenza vaccine preparations. The CDC and AAP follow the precautionary principle, which assumes that there is no danger in doing caution even if it turns out to be unwarranted, but their actions in 1999 sparked confusion and controversy that Thiomersal is the cause of autism.
Since 2000, thiomersal vaccines in children have been thought to contribute to autism, and thousands of parents in the United States have been pursuing legal compensation from federal funds. The 2004 Institute of Medicine (IOM) committee supports the rejection of a causal relationship between vaccines and thiomersal-containing autism. The incidence rate of autism increases steadily even after thiomersal is excluded from childhood vaccines. There is currently no scientific evidence that thiomersal exposure is a contributing factor to autism.
Tooth amalgam poisoning
Dental amalgam is a possible cause of low-level mercury poisoning due to its use in dental fillings. Discussions on this topic include a debate about whether an amalgam should be used, with a criticism stating that its toxic effects make it unsafe.
Cosmetics
Some skin whitening products contain toxic mercury (II) chloride as the active ingredient. When applied, these chemicals easily absorb through the skin into the bloodstream. The use of mercury in cosmetics is illegal in the United States. However, cosmetics containing mercury are often imported illegally. After a certified mercury poisoning case resulting from the use of imported skin whitening products, the US Food and Drug Administration warns against the use of such products. The symptoms of mercury poisoning have resulted from the use of various cosmetic products containing mercury. The use of skin whitening products is very popular among Asian women. In Hong Kong in 2002, two products were found to contain between 9,000 and 60,000 times the recommended dosage.
Fluorescent lamp
The fluorescent lamp contains mercury, which is released when the lamp is broken. Mercury in tubers is usually present either as a liquid mercury element, vapor, or both, as the liquid evaporates at room temperature. When damaged indoors, the bulb can remove enough mercury vapors to cause health problems, and the US Environmental Protection Agency advises to evacuate and broadcast the room for at least 15 minutes after breaking the fluorescent light bulb. Damage to some bulbs raises a greater concern. A 1987 report describes a 23-month-old infant with anorexia, weight loss, irritability, sweating, and flaking and redness of fingers and toes. The case of acrodynia was tracked on mercury exposure from an 8 foot fluorescent cardboard carton that had been broken in a pot adjacent to the main breeding. Glass is cleaned and discarded, but the child often uses the area to play.
Murder
Mercury has been used at various times to kill people. In 2008, Russian lawyer Karinna Moskalenko admitted to being poisoned by mercury left in her car while in 2010 journalist Viktor Kalashnikov and Marina Kalashnikova accused the Russian FSB of trying to poison them.
See also
References
External links
- Dangerous Substances: Mercury in Curlie (based on DMOZ)
- Toxic Substances: Mercury in Curlie (based on DMOZ)
Source of the article : Wikipedia
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