Geological classification

How does mercury affect the human body?

There are different forms of mercury—elemental (or metallic), inorganic (to which people may be exposed in the workplace), and organic (for example, methylmercury, which people may be exposed to through food). These forms of mercury vary in their degree of toxicity and in their effects on the nervous, digestive and immune systems, as well as the lungs, kidneys, skin and eyes. In nature, mercury is found in the earth’s crust. It is released into the environment as a result of volcanic activity, weathering of rocks and as a result of human activity. The main cause of mercury release is human activity, especially energy generation in coal-fired power plants, the combustion of coal in homes for heating and cooking, industrial processes, the use of waste incinerators, and the mining of mercury, gold and other metals. Once in the environment, mercury can be converted by bacteria into methylmercury. Methylmercury then bioaccumulates in fish and shellfish (bioaccumulation occurs when concentration levels in an organism exceed those found in the environment). Methylmercury is also biomagnified. For example, large predatory fish are more likely to contain high levels of mercury as a result of eating many smaller fish that accumulate mercury by eating plankton. People can be exposed to mercury in any form in a variety of circumstances. However, the main exposure occurs through consumption of fish and shellfish contaminated with methylmercury and through worker inhalation of elemental mercury during industrial processes. Heat processing of food does not destroy mercury.

Exposure to mercury

  • type of mercury;
  • dose;
  • age or stage of human development (the intrauterine fetus is most vulnerable);
  • duration of exposure;
  • route of exposure (inhalation, ingestion or skin contact).

In general, two groups are most sensitive to mercury exposure. The human fetus is the most sensitive to mercury exposure; mercury can affect its development. Fetal exposure to methylmercury during fetal development may occur through maternal consumption of fish or shellfish. This may have an adverse effect on the baby’s brain and nervous system development. The main health consequence of methylmercury exposure is neurodevelopmental impairment. Therefore, children who were exposed to methylmercury in utero may have impaired cognitive thinking, memory, attention, speech, as well as fine motor skills and hand-eye coordination.

The second group are people who are regularly exposed (chronically) to high levels of mercury (people who live by fishing or people exposed in workplaces). Among certain groups of the population living by fishing, from 1,5 to 17 children per thousand suffer from cognitive impairment (moderate mental retardation) caused by the consumption of fish containing mercury. Such populations exist in Brazil, Canada, China, Colombia and Greenland.

Significant human health exposure to mercury occurred in Minamata, Japan, during 1932–1968, when an acetic acid plant discharged liquid waste into Minamata Bay. The waste contained high concentrations of methylmercury. The bay had a lot of fish and shellfish, which were the main food for local residents and fishermen from other areas. For years, no one realized that the fish were contaminated with mercury and that it was causing a strange illness among the local community and in other areas. At least 50 people were affected to some degree, and more than 000 cases of Minamata disease were confirmed. Minamata disease peaked in the 2s, when severe cases of the disease occurred with brain damage, paralysis, incoherent speech, and impaired consciousness.

Health effects of mercury exposure

Elemental mercury and methylmercury are toxic to the central and peripheral nervous systems. Inhalation of mercury vapor can have harmful effects on the nervous, digestive and immune systems, lungs and kidneys and can cause death. Inorganic mercury salts are corrosive to the skin, eyes and gastrointestinal tract and may cause kidney toxicity if ingested.

Neurological and behavioral disorders may occur following inhalation, ingestion, or dermal contact with various mercury compounds. Symptoms include tremors, insomnia, memory loss, neuromuscular disorders, headaches, and cognitive and motor dysfunction. Mild, non-clinical signs of central nervous system toxicity may occur in workers exposed to airborne elemental mercury levels of 20 mg/m3 or higher for several years. Effects on the kidneys have been reported, ranging from increased protein levels in the urine to kidney failure.

How can we reduce human exposure to mercury sources?

There are several ways to prevent adverse health effects, including promoting the use of clean energy sources, eliminating the use of mercury in gold mining, ending mercury mining, and eliminating non-essential products containing mercury.

Encourage the use of clean, non-coal energy sources

Burning coal for energy and heat is a major source of mercury. Coal contains mercury and other dangerous pollutants that are released into the air when coal is burned. Almost half of the mercury released into the air comes from coal-fired power plants, industrial boilers and home furnaces.

End mercury mining and the use of mercury in gold mining and other industrial processes.

Mercury is an element that cannot be destroyed; therefore, mercury already in use can be reused in other important applications without further need for mercury mining. The use of mercury in non-industrial and small-scale gold mining is particularly hazardous, and the health impacts on vulnerable populations are significant. Gold mining technology that does not use mercury (cyanide-free technology) needs to be promoted and implemented, and where mercury is still used, safer work practices need to be implemented to prevent exposure.

Remove non-essential mercury-containing products from production and safely handle, use and dispose of remaining mercury-containing products.

Mercury is found in many foods, including the following:

  • galvanic cells;
  • measuring instruments such as thermometers and barometers;
  • electrical switches and relays in equipment;
  • lamps (including some types of light bulbs);
  • amalgam for dental fillings;
  • skin lightening products and other cosmetics;
  • pharmaceuticals.

A number of actions are being taken to reduce mercury levels in products or to phase out products containing mercury. In healthcare, mercury thermometers and sphygmomanometers are being replaced by alternatives.

Amalgam for dental fillings is used in almost all countries. In 2009, a WHO expert consultation concluded that a global ban on amalgam in the near future would be problematic for public health and the dental sector, but that a gradual reduction in its use should be promoted through disease prevention and the promotion of alternatives; conducting research and development of cost-effective alternatives; training specialists in the field of dentistry and raising public awareness.

Inorganic mercury is added to some skin lightening products in significant quantities. In many countries, skin lightening products containing mercury are banned due to their risk to human health.

Use of mercury in vaccines and pharmaceuticals

Mercury in the form of thiomersal (ethylmercury) is used in very small quantities as a preservative in some vaccines and pharmaceuticals. Ethylmercury is significantly different from methylmercury. Ethylmercury is quickly broken down in the body and does not accumulate. For more than 10 years, WHO has closely monitored the scientific evidence regarding the use of thiomersal as a vaccine preservative and has consistently reached one conclusion: there is no evidence that the amount of thiomersal used in vaccines poses a health risk.

Political agreement

The continued release of mercury into the environment from human activities, the presence of mercury in the food chain and the adverse effects it exhibits in humans are of great concern, which is why governments adopted the Minamata Convention on Mercury in 2013. The Convention requires governments that are Parties to take a number of measures, including measures to prevent the release of mercury into the air and to phase out certain products containing mercury.

WHO activities

WHO publishes evidence on the health effects of different forms of mercury, guidance on identifying populations at risk of exposure to mercury, techniques for reducing exposure to mercury, and guidance on replacing mercury-containing thermometers and blood pressure monitors in healthcare. WHO is leading projects to promote prudent management and disposal of health-care waste and has contributed to the development of an affordable, approved, mercury-free blood pressure monitor.

Currently, in the industrial regions of Russia, the situation with mercury pollution of the environment has worsened.

The danger is due to the fact that no other chemical element included in the group of highly toxic substances has:

  • such wide application in production processes, products, substances, etc.;
  • such widespread availability (used in medical thermometers, fluorescent and arc-discharge lamps, mercury flow meters, instruments, chemical, defense industries, etc.);
  • similar severity of toxic effects (according to medical parameters in general and sanitary and hygienic standards in particular);
  • such diverse routes of entry into the body (through the respiratory tract, gastrointestinal tract, skin);
  • similar ability to accumulate in plant and animal tissues.

In addition, the high toxicity of mercury and its waste is also explained by certain physicochemical properties, which make it possible to compare mercury contamination with radioactive contamination. This is the high volatility of mercury and its compounds, which increases progressively with increasing ambient temperature; stability in the external environment; solubility of mercury vapor in precipitation; ability for sorption by soil and adsorption of suspended particles from the aquatic environment; the ability to form methylmercury in natural bodies of water and accumulate in fish tissues; lack of smell and taste.

And at the same time, of all the sanitary, hygienic and environmental problems associated with chemical pollution of the environment, mercury is one of the least studied. For several decades, hundreds of millions of used mercury-containing light sources (fluorescent and gas-discharge lamps) have been dumped in landfills in our cities. Mercury from broken lamps enters the atmosphere, soil and water. Spent mercury devices and products containing large amounts of metallic mercury (mercury flow meters, ignitrons, tonometers, thermometers, etc.) are thrown into landfills.

The situation is aggravated by the fact that mercury and mercury-containing waste are increasingly becoming a weapon of crime, used against the life and health of people, as well as to destabilize the work of institutions.

Among the most pressing environmental problems, issues related to environmental pollution with mercury and its compounds occupy an important place. This is due, on the one hand, to the widespread use and periodic failure of various mercury-containing products (including fluorescent lamps) in everyday life, healthcare institutions, transport, preschool, educational and scientific institutions, and on the other hand, to the high toxicity of mercury.

INFLUENCE OF MERCURY ON HUMAN HEALTH

According to the modern classification, mercury is classified as an extremely toxic substance (hazard class I).

The average person (70 kg body weight) contains approximately 13 mg of mercury, but it does not appear to have any physiological role. At least, the vital necessity of this metal for humans and other organisms has not been proven. Recently, reports have begun to appear in the scientific literature that mercury has a certain biotic effect and has a stimulating effect on vital processes (in quantities corresponding to physiological, i.e., normal for humans, concentrations). There is information about the presence of mercury in the nuclear fraction of living cells and about the importance of this metal in the implementation of information embedded in DNA and its transmission using transfer RNA. To put it simply, the complete removal of mercury from the body is apparently undesirable, and those same 13 mg, “embedded” in us by nature, should always be contained in a person (which, by the way, is quite consistent with the above-mentioned Clark-Vernadsky law on the general dispersion of elements) . At the same time, it has been reliably established that mercury (in doses exceeding the physiological requirement, which, unfortunately, is easily achieved) is toxic to all forms of life, and in almost any state, with rare exceptions. Thus, ingesting metallic mercury is relatively harmless, and it is eliminated through the gastrointestinal tract. But experimenting is strictly not recommended, and if this happens, you should immediately consult a doctor! Ingestion of 1 g of mercury salt is fatal. In terms of “pure” mercury, 150-300 mg is enough for this; harmful effects occur at a dose of “pure” mercury of 0,4 mg.

From the point of view of human pathology, mercury has an extremely wide spectrum and a wide variety of manifestations of toxic effects, depending on the properties of the substances in the form of which it enters the body (metallic mercury vapor, inorganic or organic compounds), routes of entry and dose. It has a negative impact on adults and children, men and women. The main routes of human exposure to mercury are associated with air (breathing), food, and drinking water. Of particular importance is occupational exposure, which is significant in those industries where mercury is used in technological processes. Excretion in urine and feces are the two main ways mercury is excreted from the body. Evaporation from the lungs, sweat, and salivation are of less importance.

Mercury is one of the thiol poisons that blocks the sulfhydryl groups of protein compounds and thereby disrupts protein metabolism and enzymatic activity of the body. It especially affects the nervous and excretory systems. When exposed to mercury, acute (manifest quickly and sharply, usually with large doses) and chronic (influence of small doses of mercury over a relatively long time) poisoning are possible. Mercury vapors and inorganic compounds cause contact dermatitis. When inhaled, mercury vapor is absorbed and accumulates in the brain and kidneys. Approximately 80% of inhaled mercury vapor is retained in the human body. Almost complete absorption of methylmercury occurs in the gastrointestinal tract. There is evidence that many forms of mercury can enter the human body through the skin. In pregnant women, mercury crosses the placental barrier, affecting the fetus. Methylmercury also passes into breast milk, accumulating to dangerous levels in the blood of children.

Chronic mercury poisoning leads to damage to the nervous system and is characterized by the presence of asthenovegetative syndrome with distinct mercury tremor (trembling of the hands, tongue, eyelids, even legs and the whole body), unstable pulse, tachycardia, excited state, mental disorders, gingivitis. Apathy, emotional instability (mercurial neurasthenia), headaches, dizziness, insomnia develop, a state of increased mental excitability occurs (mercurial erethism), and memory is impaired. Inhalation of mercury vapor with strong exposure is accompanied by symptoms of acute bronchitis, bronchiolitis and pneumonia. Changes in the blood and increased excretion of mercury in the urine are observed. Many symptoms of mercury vapor poisoning disappear when exposure is stopped and appropriate measures are taken, but complete elimination of mental disorders is difficult to achieve. Extremely acute mercury poisoning causes lung destruction. As a rule, the noted syndromes and symptoms are observed when exposed to mercury vapor at concentrations in the air of more than 0,1 mg/m. But mental disorders can also occur at lower concentrations. Thus, with prolonged exposure to low concentrations of mercury vapor in the air – no more than hundredths of mg/mXNUMX – people develop mercurialism. Typically, its manifestations are initially expressed in decreased performance, fatigue, and increased excitability. Then these phenomena intensify, memory impairment occurs, anxiety and self-doubt, irritability and headaches appear. Possible catarrhal phenomena in the upper respiratory tract, bleeding gums, discomfort in the heart, slight trembling (weak tremor), increased urination, etc.

Organic derivatives of mercury are very toxic. The most important signs of poisoning by them are severe damage to the central nervous system, ataxia (disorder of coordination in the contraction of various muscle groups), visual impairment, paresthesia (feelings of numbness, tingling, crawling, etc.), dysarthria (speech disorder), hearing impairment, pain in the extremities – established and described in detail after well-known methylmercury poisonings in Japan and Iraq. These phenomena are practically irreversible and require extremely long-term treatment in order to at least reduce them. The high toxicity of methylmercury (even when ingested in small quantities over a long period of time) is due to its lipid solubility, which allows it to more easily pass through biological membranes, penetrate the brain, spinal cord, peripheral nerves, and also cross the placental barrier and accumulate in the fruit. Methylmercury completely destroys the nerve cells of the central nervous system. An analysis of the effects of illness in Japan and Iraq showed that mothers who suffered mild mercury poisoning gave birth to children with severe cerebral palsy. Thus, the fetal period represents a stage of the life cycle that is very sensitive to mercury exposure.

It has now been established that, along with a general toxic effect (poisoning), mercury and its compounds cause gonadotoxic (effects on the gonads), embryotoxic (effects on embryos), teratogenic (malformations and deformities) and mutagenic (the occurrence of hereditary changes) effects. There is information about the possible carcinogenicity of inorganic mercury.

We do not claim authorship of this article under any circumstances!

This is a summary from many sources.
All of them have been tested and are very authoritative in the scientific community.
Here we have simply tried to explain all those harmful
and in most cases – irreversible effects on the human body,
which mercury and especially its compounds have.
This article is a reason to think for those people who
who, with a calm grin on their face, bury
tons of mercury-containing waste into the ground,
presenting a “surprise” to future generations – their grandchildren and great-grandchildren.

But we are more than sure
that none of these barbarians read this article to the end.

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