Mercury Poisoning From Fish Symptoms

Mercury is highly toxic. Anyone who comes into contact with this heavy metal (even in small quantities) can develop serious health problems. How can this be avoided and what should be done in the event of poisoning? This text corresponds to the specifications of medical literature, medical guidelines and current studies and has been reviewed by medical professionals.

  • Mercury: Even small amounts are enough for poisoning
  • Mercury poisoning: symptoms & therapy

Mercury: Even small amounts are enough to cause poisoning

Mercury is a natural component of the earth’s crust and is found in the environment worldwide. Human exposure to mercury is partly due to natural causes: The heavy metal is released, for example, during volcanic eruptions, from geysers or during forest or steppe fires. But However, humans are mainly responsible for the release of mercury: We release mercury primarily when we burn fossil fuels, but also in mining, smelting, and industry. Most of the mercury released enters the Earth’s atmosphere and is dispersed around the globe with air currents. Precipitation transports the mercury back to the earth’s surface, where it is deposited in water and soil. From there, it enters the food chain. Only when the mercury is trapped again in deep soil layers can it no longer spread. By the way: Mercury is indestructible.

Is mercury always toxic?

No. Whether and to what extent mercury causes harm in the body depends primarily on

  • the form of mercury (elemental/inorganic/organic),
  • the mercury dose,
  • the age or developmental stage of those affected (fetuses are most sensitive),
  • the duration of contact, and
  • the type of contact (inhalation, consumption, skin contact).

Elemental mercury endangers health – especially when its vapors are inhaled. This metal, which is liquid at room temperature, used to be in many thermometers. Also, the organic mercury compound called methylmercury is also toxic – to humans and animals. Methylmercury accumulates in the body – marine animals in particular are heavily contaminated with it. In contrast, the organic mercury compound called ethylmercury is harmless. The body quickly converts ethylmercury into inorganic mercury, which it excretes in the stool. Ethylmercury is present in small amounts in some vaccines, for example, as a preservative.

Just how toxic mercury is was demonstrated in the Japanese city of Minamata

For many years, a local chemical company disposed of waste containing large quantities of methylmercury in Minamata Bay. As a result, this form of mercury accumulated in fish and shellfish. Many of these marine animals continued to end up on the plates of people who were unaware of their exposure to mercury. The result: Especially in the 1950s, thousands of people in Minamata fell ill with mercury poisoning – and over 2,000 people died as a result.

What do humans use mercury for?

Around the world, mercury is used in a variety of applications. For example, the following products may contain mercury:

  • Batteries
  • measuring devices, such as thermometers and barometers
  • electrical switches and relays in appliances
  • lamps (including some types of light bulbs)
  • amalgam (for dental fillings)
  • skin whitening products and other cosmetics
  • pharmaceuticals

However, in many countries, including Germany, the use of mercury has now been severely restricted or banned altogether (e.g. in thermometers or skin whitening products).

How does mercury enter the body?

In Germany, the main sources are diet and amalgam are responsible for the mercury load in humans. On average, about as much mercury enters the body from amalgam fillings as from food. For most people, however, the measurable concentration of mercury in the blood or urine is so low that no serious risk to health. health.

Mercury in food

Mercury is found primarily in fish and seafood – in the form of Methylmercury. Long-lived fish with a predatory lifestyle have a particularly high mercury content because they accumulate more methylmercury (e.g. sharks, swordfish, pike and tuna). But other animals that eat a lot of fish are also often heavily contaminated (e.g. waterfowl). ” width=”770″ /> The older a fish is and the higher it is in the food chain, the greater the risk that it contains a lot of mercury. Besides fish other foods such as cereals, vegetables, meat, fruit, nuts and cocoa. However, mercury is predominantly found in inorganic or elemental form, which is which is less harmful to human health. Those who eat sea fish particularly frequently (especially certain predatory fish such as pike or tuna) risk ingesting mercury in amounts that are harmful to health.

Mercury in amalgam

Amalgam used as a dental filling contains mercury. However, as a rule, amalgam fillings do not pose a health risk of mercury exposure. However, the release of mercury from amalgam fillings can be increased if

  • someone has many amalgam fillings,
  • the amalgam fillings have large surface areas,
  • the amalgam fillings are affected,
  • there are other metallic fillings in addition to amalgam fillings, which are in direct contact with the amalgam.

Therefore, as a precautionary measure, amalgam may only be used in pregnant and breastfeeding women as well as in children under 15 years of age. children under the age of 15 used as a dental filling.

What does mercury do to the body?

If the gastrointestinal mucosa is undamaged, swallowed mercury practically does not enter the body from the gastrointestinal tract at all. However, inhaled mercury vapors or organic mercury compounds can be harmful to health. Elemental mercury and methylmercury are better absorbed by the body and can also enter the brain from the blood. They are toxic to the nervous system. Inhalation of mercury vapor can damage the nervous system, digestive system, immune system, lungs and kidneys, and in extreme cases can be fatal. Inorganic mercury salts can cause burns to the skin, eyes, and gastrointestinal tract, and (after ingestion) can impair kidney function. In addition, mercury can affect the development of children in the womb and in the early stages of life after birth. How mercury poisoning manifests itself depends primarily on,

  • what form of mercury is involved and
  • whether the exposure occurred suddenly or over a long period of time (acute/chronic poisoning).

Mercury poisoning: symptoms & therapy

Vaporous metallic mercury poisoning

Vaporous metallic mercury (e.g., from broken mercury thermometers) easily enters the body through the lungs and accumulates in the brain. When it is converted to inorganic mercury salts in the body, they can no longer pass from the blood to the brain. The body excretes them through the kidneys and stool. The symptoms of acute poisoning by vaporous mercury resemble pneumonia with: A constant long-term contact with mercury vapor can also cause the following symptoms:

  • tremor (tremor)
  • inflammation of the dental bed
  • increased salivation
  • metallic taste

To therapy the antidote DMPS (dimercaptopropane sulfonate) is suitable.

Poisoning by inorganic mercury salts

If inorganic mercury salts (e.g. mercury sulfide, mercury oxide or mercury chloride) are swallowed, ten percent of them enter the body via the gastrointestinal tract. They can only penetrate the placenta and the brain incompletely. The body also excretes them through urine and stool. The most important symptoms of acute poisoning with inorganic mercury salts are:

  • Burns in the oral cavity, pharynx and esophagus,
  • gastrointestinal complaints (such as nausea and vomiting),
  • subsequently kidney damage,
    • initially with pathologically increased urine quantity (polyuria),
    • later with reduced urine quantity (oliguria to anuria),
  • accompanied by intestinal colic with violent diarrhea.

In cases of acute poisoning with mercury salts, rapid action is required. If the ingested amount of inorganic mercury salts is potentially toxic, the Therapy in:

  • gastric lavage (during gastroscopy) to remove the mercury,
  • the administration of activated carbon (and possibly protein powder) to bind residual mercury, and
  • new chelating agents such as DPMS or D-penicillamine as antidotes.

Poisoning by organic mercury salts

Organic mercury salts enter the body from the gastrointestinal tract 90 percent of the time after ingestion. They easily pass from the blood into the brain and accumulate there. Typical symptoms of acute poisoning with organic mercury salts are:

  • Agitation
  • Skin sensations (paresthesias)
  • trembling
  • convulsions

To therapy the same remedies are suitable as for inorganic mercury compounds:

  • Gastric lavage
  • activated charcoal
  • protein powder
  • DPMS or D-penicillamine as antidote

Tips against avoidable mercury exposure …

  • … for fish eaters: When eating fish, it’s all about the quantity! Fish eaten in large quantities (e.g. trout) and fish products can contribute greatly to mercury exposure, even if they contain only a small amount of methylmercury.
  • … for pregnant women: Pregnant women should be especially careful not to eat sea fish (e.g., tuna) several times a week. The intake of mercury can endanger the health of unborn children.
  • … for nostalgics: You still have an old clinical thermometer with mercury? If the thermometer breaks, so that mercury escapes, pick up the remains e.g. with a bent paper and put them into a sealable glass container. Then ventilate the room well several times and dispose of the tightly closed container together with the mercury properly.
  • … for energy savers: The same applies to handling broken energy-saving lamps as to mercury thermometers – ventilate well and dispose of mercury properly. It’s best to make sure it doesn’t get that far in the first place, e.g. by only buying energy-saving lamps with shatter protection and only using them in stable luminaires.
  • … for parents: If mercury gets into your child’s mouth (e.g. because he or she has bitten on a mercury thermometer), off to the doctor! The doctor can aspirate possible mercury residues in the oral cavity and administer an antidote if necessary.
  • … for bargain hunters: In some countries there are still mercury-containing products that have long been banned in this country. Therefore, do not buy medicines or skin creams from questionable sources abroad (e.g. via the Internet).

Last update: 05.01.2022 Author*in Astrid Clasen (Medical editor) Sources Online information of Pschyrembel: (retrieval date: 16.7.2018) Fact Sheet: Mercury and health. Online information of the World Health Organization (WHO): (retrieval date: 3/31/2017) Mercury – Risk for humans and the environment? Online information of the Federal Environment Agency: (as of 4.5.2016) Graefe, K.H., et al.: Duale Reihe Pharmakologie und Toxikologie. Thieme, Stuttgart 2016 Herdegen, T.: Kurzlehrbuch Pharmakologie und Toxikologie. Thieme, Stuttgart 2014 Information brochure of the Federal Office for Risk Assessment (ed.): Aufnahme von Umweltkontaminanten über Lebensmittel. Federal Office for Risk Assessment, Berlin (4.1.2011) Press release of the Federal Environment Agency: mercury from broken energy-saving lamps (2.12.2010).

Onmeda reading tips:

Amalgam (amalgam filling): This is what you should know Off for amalgam in children, pregnant women and nursing mothers The mercury load of many fish species is now so high that children and women of childbearing age are at risk. Leading mercury researchers issued a declaration today (Thursday) warning of the health risks of eating fish. Tuna are also particularly contaminated. (Photo: Reuters) The mercury load of many fish species is already so high that especially children and women of childbearing age are endangered by the toxic heavy metal. Today, three times as much mercury falls from the sky as before the industrial revolution. Although mercury emissions in industrialized countries have fallen over the past 30 years, rising industrial emissions in developing countries have compensated for this decline. The declaration was formulated by 37 international mercury specialists and published by the Royal Swedish Academy of Sciences in the current issue of the journal Ambio. In it, the specialists summarize 33 scientific findings from mercury research over the past decade. The declaration is supported by 1150 scientists. The toxicologists, biologists and environmental researchers name in particular smaller gold mines as the main cause of the increasing pollution of the environment with the heavy metal. Ten percent of the mercury in the atmosphere alone comes from gold mining, where it is used to wash the ore out of the rock. In small mines, mercury is often released into the environment in an uncontrolled manner. The health of 50 million people around the world is directly threatened.

At the top of the food chain

But even those who do not live in the vicinity of gold mines are contaminated by mercury: Mercury concentrations in fish, as well as birds and mammals that eat fish, are steadily increasing worldwide and have already reached toxic levels in many places. The heavy metal accumulates in the form of methyl mercury – a compound that is about a hundred times more toxic than ordinary mercury – particularly in fatty fish, and thus enters the food chain. This is already threatening the survival of local fish populations. In humans, mercury has been shown to harm the fetus and may increase the risk of cardiovascular disease. The researchers’ warning casts doubt on whether fish can still be eaten without hesitation. The Federal Institute for Risk Assessment has given the all-clear in part: the limits for mercury are complied with for the most popular types of fish among Germans – herring, trout, pollock and carp. Jörg Oehlenschläger, deputy director of the institute at the Federal Research Centre for Nutrition and Food in Hamburg, also reassures: “97 percent of the fish that come onto the table in Germany can be eaten without concern.”

Warning against tuna and shark

However, the food chemist warns against eating swordfish, tuna, white halibut and shark: “These fish species are at the top of the food chain and also grow quite old. Over their lifetime, therefore, they store more mercury than other species.” In addition, women of childbearing age, pregnant women, nursing mothers and young children should eat fish no more than once a week, even in Germany, Oehlenschläger recommends. The Institute of Medicine of the U.S. National Academy of Science also confirms the risks of mercury exposure from fish consumption. Nevertheless, the benefits to health outweigh the risks, the physicians write in an as yet unpublished study: selenium, iodine and omega-3 fatty acids are valuable ingredients of fish that compensate for the negative effects of mercury. However, the researchers advise a varied fish diet to vary between more and less contaminated species. Even if mercury causes few problems in industrialized countries such as Germany when simple tips are followed, Oehlenschläger believes the declaration is highly relevant for other parts of the world: “A lot of swordfish is eaten, especially in the tropics. Therefore, the risk is highest there.” The Declaration’s lead author, James Wiener of the University of Wisconsin in Madison, therefore says: “Mercury pollution in the environment is a problem of global proportions. We urge policymakers to develop effective international strategies and finally address the problem.” At Mercury (Hydrargyrum (Hg), Mercurius) is an element from the group of heavy metals. Mercury is found in many areas of daily life (e.g. amalgam fillings). In addition, we ingest mercury with our food (fish and seafood can be contaminated with mercury (methylmercury) – especially predatory fish species: swordfish, tuna; sometimes also buttermackerel, trout, halibut, carp). Mercury occurs in various inorganic and organic compounds. Acute mercury poisoning can be distinguished from subacute and chronic mercury poisoning (mercurialism). Signs of chronic mercury poisoning are expected only after at least one year of exposure to more than 50 μg/m³. In acute mercury poisoning, the following symptoms may occur:

  • Burning pain in the esophagus
  • Renal dysfunction due to destruction of the renal tubules up to uremia (kidney failure)
  • Nausea (nausea)/vomiting
  • Inhalation of larger amounts of mercury leads to irritation of the respiratory tract and damage to the central nervous system

In subacute mercury poisoning, the following symptoms may occur:

  • Gingivitis (inflammation of the gums), which can lead to the formation of a dark bluish-purple fringe on the gums and lips
  • Nephropathy (kidney disease), unspecified
  • Intestinal damage, unspecified, associated with diarrhea (diarrhea)
  • Increased saliva production
  • Stomatitis (mercurialis) (inflammation of the oral mucosa)
  • Tooth loss

Chronic mercury poisoning may result in the following symptoms:

  • Dermatitis mercurialis – form of inflammatory skin reaction
  • Diarrhea (diarrhea)
  • Gingivitis (inflammation of the gums) – sometimes a bluish-purple “mercury fringe
  • Pain in the limbs
  • Hearing disorders
  • Insomnia (sleep disturbances)
  • Cachexia
  • Concentration disorders
  • Headache
  • Paralysis
  • dullness
  • Psellismus mercurialis – stuttering speech
  • reddening of the pharyngeal ring (so-called “mercury throat”)
  • visual disturbances
  • Stomatitis (mercurialis) with increased salivation, sometimes also dry mouth
  • Tremor mercurialis – involuntary trembling
  • Tooth loosening and loss
  • CNS symptoms such as:
    • Ataxia (gait disturbances)
    • Erethismus mercurialis – greatly increased excitability (jumpiness) and with a strong urge to move as well as anxious self-consciousness, sensitivity, shyness and mood lability
    • memory disorders and personality degradation
    • mercurial tremor (tremor mercurialis)
    • sensory and motor paresis (paralysis)
    • Speech disorders (psellism mercurialis – stuttering speech/ washed out sibilants)
    • sensory disturbances

Chronic mercury poisoning by oral ingestion is known in Japan as Minamata disease known.

The procedure

Material needed

  • EDTA blood
  • Urine
  • 24h-collection urine (before/basal and after DMPS administration)
  • (saliva samples; before and after chewing gum)

Preparation of the patient

  • Not necessary
  • Collect 24h urine (basal value); next morning DMPS administration (3 tablets = 300 mg DMPS orally with 300 ml water) and again 24h urine (loading value)

Interfering factors

  • Not known

Normal values – blood

Normal value < 7.2 μg/l
BAT value 50 μg/l (alkyl Hg compounds) 100 μg/l ((in)organic compounds)

Standard values – urine

Normal value < 24.6 μg/l < 38.9 μg/g creatinine
After DMPS administration < 50 μg/l
BAT value 200 μg/l

Normal values – saliva

BAT value: biological agent tolerance value


  • Suspicion of mercury poisoning


Interpretation of lowered values

  • Not relevant to disease

Interpretation of elevated values

  • Occupational exposure (recognized as occupational disease)
    • Agriculture: fungicides, seed dressings
    • Pyrotechnic and explosives industry
    • Production of wood preservatives
    • chemical and pharmaceutical industry
    • Dentistry – alloys with mercury (amalgam)

Attention. Organic mercury compounds are more toxic than inorganic compounds! Further hints

  • The chewing gum test according to Daunderer (saliva sample!) – for estimating the mercury load from amalgam fillings – cannot be recommended.
  • In case of symptoms of poisoning, one can try to eliminate mercury with DMPS (2,3-dimercaptopropane-1-sulfonic acid).


  1. S1 Guideline: Working under the influence of mercury and its compounds. (AWMF register number: 002 – 003), July 2014 Long version.

The health and medical information provided for you on our homepage does not replace professional advice or treatment by a licensed physician. Health world of the AOK Saxony-Anhalt

How mercury works in our body

You have probably heard of mercury many times in your life. Mankind has been using it in all kinds of areas for many years. Until the beginning of the 20th century, the substance was used to treat many diseases. However, due to its toxic fumes, it did more harm to the people being treated and the medical staff than it did to promote the healing process. Nevertheless, mercury poisoning is not a phenomenon of the past. For even in our time, we can hardly avoid coming into contact with mercury on a regular basis in our everyday lives. But how does this happen? What is mercury still present in today? How does mercury poisoning manifest itself? And how is it treated? In this article you will learn everything that is important on this subject.

Did you know that…

  • Mercury is found in many areas of our lives?
  • predatory fish are particularly heavily contaminated with mercury?
  • the “heavy metal controlled” seal identifies mercury-free products?

Mercury – what it is and where it is found

Mercury belongs to the heavy metals and occurs naturally in the environment. The name mercury means “living silver” and it couldn’t be more appropriate: The substance is the only metal that is liquid at room temperature, and it beads off all surfaces. The vapors emitted by mercury in its liquid state are highly toxic to humans. We come into contact with small amounts of the element in many areas of our daily lives because it is involved in, or produced by, numerous processes. In medicine the use of mercury is largely frowned upon. However, dental fillings made from amalgam and some vaccines contain small amounts of the heavy metal. In addition, mercury was used extensively in the manufacture of clinical thermometers until a few years ago. Because of the risk that these could break, releasing the heavy metal, the sale of new thermometers containing mercury has been banned in the EU since 2009. In food fish and seafood in particular are contaminated with mercury. Especially in predatory fish such as tuna and swordfish, the amount can be elevated, since these species in turn feed on fish and thus store more mercury. In the air we breathe mercury ends up in the air we breathe due to combustion gases from coal-fired power plants. Lignite-fired power plants in particular release larger amounts of the heavy metal into the atmosphere, where it pollutes the air we breathe in the surrounding area and enters the soil and groundwater through rain showers. In the household mercury is nowadays mostly found only in energy-saving lamps – with the exception of LED and halogen lamps. The amount that is processed in the production of the lamps is quite small. However, if a bulb ever breaks in your home, you should air your living quarters thoroughly right away and dispose of the broken pieces without touching them. With all these points of contact with the heavy metal and the fact that it occurs naturally, it is not surprising that it is detectable in everyone. We absorb it through our lungs, skin and through our food. How much an organism is burdened with mercury can be determined by urine and blood tests. As a rule, however, this exposure is so low in Germany that it has no effect on our health. Nevertheless, knowledge about mercury sources is important, because larger amounts of the heavy metal are highly toxic and can trigger severe health symptoms.

Mercury poisoning

Mercury poisoning, also known as mercurialism, occurs in two different ways.

Acute mercury poisoning

Acute poisoning is when a person has been exposed to a high amount of mercury vapors in a short period of time. This can be the case, for example, if an old clinical thermometer or an energy-saving lamp has broken. The toxic vapors enter the organism through the lungs and the body wants to get rid of the poison as quickly as possible. Nausea and vomiting are the result and, delayed in time, affected persons can develop severe diarrhea. In addition, if the poisoning is not treated quickly, symptoms such as restlessness, nervousness, tremors, cramps and headaches may be added and the mouth and throat feel dry.

Chronic mercury poisoning

Chronic mercury poisoning is also known as Minimata disease. It was named after the Japanese coastal town of Minimata, where contaminated chemical wastewater caused a wave of severe mercury poisoning in the 1960s. Chronic poisoning develops when people repeatedly ingest small amounts of mercury over a long period of time. This happens, for example, through diet. In the body, the heavy metal is stored in the nervous system, kidney and liver, among other places. However, health complaints only occur when the limit value for mercury in the body has already been exceeded. The symptoms are very diverse:

  • Mouth and throat: frequent bleeding gums, loss of teeth, mouth sores, and metallic taste
  • Blood vessels and heart: abnormal heart rhythm and abnormal blood pressure
  • Overall physical symptoms: Fatigue, profuse night sweats, abnormal body temperature, kidney ailments, and loss of appetite accompanied by severe weight loss

Mercury persists in the body for quite a long time. For example, it can be detected in the blood for over a month. If it has already migrated further into the body via the blood, it can only be excreted after about two months. It can even remain in the brain for several years and cause serious damage in larger quantities. Therefore, you should always be careful to avoid mercury in your daily life. Because you can never be sure how much of the substance is already stored in your body.

But how much mercury is now dangerous and leads to poisoning?

Unfortunately, this question cannot be answered clearly, because various factors come together. In everyday life, it is difficult to consciously notice when you come into contact with the heavy metal, because it is odorless. In order to protect the population, there are guidelines and limits that must be observed, especially in food production. For example, edible fish such as salmon, pollock, herring and trout may contain no more than 0.3 milligrams of mercury per kilogram. Only fish species such as swordfish and shark species are in the absolute maximum content category of 2.0 milligrams per kilogram. Tuna, with a maximum of 1.0 milligrams per kilogram, lies between the two values. When buying cosmetics, dietary supplements, medicines and health products, you can look for the test mark“heavy metal controlled” which shows you that a product contains harmless amounts of mercury.

Diagnosis and treatment of mercury poisoning

Acute mercury poisoning is usually associated with an accident, for example the broken thermometer. The diagnosis then proceeds initially on the basis of the accident and treatment is carried out in intensive care in hospital. If chronic mercury poisoning is suspected, blood, urine and in some cases the hair of the affected person are tested. If there is indeed poisoning, it is treated as an outpatient. To treat mercury poisoning – whether acute or chronic – a so-called detoxification therapy is started. This means that those affected are given an antidote that binds the mercury in the body, renders it inactive and then ensures that the substance is excreted or eliminated more quickly. In most cases, this is done with the help of the trace elements zinc and selenium. In addition, vitamins A, C and E are added because they support the process of elimination. In any case, if you suspect mercury poisoning, you should contact medical professionals. Especially in an acute case, it is important to make an emergency call directly. The sooner you respond, the sooner long-term damage to the kidney, liver and brain can be avoided.

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