Know How Mercury Intoxication Occurs, Its Causes, Diagnosis, and Management

Introduction:

The accumulation of heavy metals like lead, mercury, arsenic, copper, and cadmium in excess quantities can lead to toxic changes in the body. Some of these metals are required for metabolic functions of the body in micro-quantities. Exposure to these metals can occur from industrial exposure, environmental pollutants, ingestion of certain foods and medicines, etc.

Symptoms of these toxic changes vary according to the type of metal accumulated. In addition, the severity varies from minor skin changes to life-threatening complications. Therefore, it is essential to consider heavy metal poisoning as a diagnosis if such symptoms are present.

What Is Mercury Intoxication?

Mercury is a heavy metal that exists as a liquid at room temperature. It is a naturally occurring chemical that exists in several forms:

• Elemental (metallic) mercury.

• Inorganic mercury compounds.

• Methylmercury and other organic compounds.

Small amounts of mercury are present in the food products that we consume every day; therefore, some amount of mercury exposure is bound to happen. Mercury toxicity occurs when the body is exposed to an excess quantity of mercury through various sources. The symptoms vary depending on the type and quantity of the mercury. According to WHO (World Health Organization), chronic exposure to metallic mercury levels in the air of 20 mcg per cubic millimeter can cause mild and sub-clinical symptoms.

What Causes Mercury Intoxication?

A. Exposure From Seafood or Fish:

Consuming seafood that contains mercury is one of the common causes of mercury poisoning. Methylmercury or organic mercury is present in a large proportion of seafood. Organic mercury is present in water and eventually enters aquatic animals, especially fish. The types of fish that contain methylmercury include bigeye tuna, marlin, king mackerel, sharks, and swordfish.

B. Inhalation of Metallic Mercury Vapor via Occupational or Dental Fillings:

Dental fillings or amalgam fillings contain 40 % to 50 % of elemental mercury. Mercury vapors are emitted from dental fillings at 2 to 28 mcg per facet surface per day. The body absorbs 80 % of this. Other common sources of elemental mercury exposure occur from mining, broken thermometers, etc.

C. Miscellaneous Causes:

These causes are rare and include mercury exposure from certain jewelry, skincare products, compact fluorescent lamp bulb leakage, old paints, certain vaccinations, etc.

What Are the Signs and Symptoms of Mercury Intoxication?

The effect of mercury intoxication on the human body mainly depends on the following:

• Type of mercury (organic, inorganic, elemental).

• Quantity and duration of mercury exposure.

• Age and systemic condition of the person exposed.

• Type of exposure (inhalation, skin contact, ingestion).

A. Effects of Methylmercury On:

Adults: Methylmercury is a neurotoxin (the substance that damages or impairs the function of nerves and the nervous system) and has various adverse effects on health.

The symptoms include:

• Visual disturbances.

• Pricking sensation in hands, feet, and mouth.

• Uncoordinated body movements.

• Weakness in the muscles.

• Impaired speech and hearing.

Infants and Children: Fetuses in the womb get exposed to mercury when mothers consume seafood that contains organic mercury. This has a serious effect on the development of the fetus as they are more vulnerable.

The effects include:

• Impaired cognitive thinking.

• Impaired motor skills.

• Impact on memory, language, and spatial awareness.

• Defective visual and speech development.

B. Effects of Elemental or Metallic Mercury:Spilled elemental mercury is usually inhaled in vapor form and absorbed into the lungs.

The symptoms occur due to chronic exposure or acute exposure in large quantities, and these include:

• Seizures and tremors.

• Sleep disturbances.

• Headache.

• Impaired sensory functions like vision, speech, hearing, etc.

• Mood swings, irritability, emotional disturbances, anxiety, etc.

• Muscle weakness, twitching, and muscle loss.

• Extreme exposure leads to kidney failure, respiratory failure, and death.

C. Effects of Inorganic and Other Mercury Compounds:Inorganic mercury in the form of salts is absorbed into the digestive system, nervous system, and kidneys.

The symptoms of exposure are:

• Dermatologic changes like rashes, itching, etc.

• Loss of memory.

• Emotional disturbances like mood swings.

• Weakness in muscles.

• Chronic and long-term exposure can lead to kidney damage.

How Dental Fillings Cause Mercury Poisoning?

Mercury exposure from dental fillings primarily happens through the release of low levels of mercury vapor from dental amalgam. This occurs when amalgam is placed, replaced, or removed, and the vapor can be inhaled and absorbed into the bloodstream through the lungs. Additionally, ingestion of tiny particles from dental amalgam, often resulting from teeth grinding or chewing on objects, can allow these particles to enter the digestive system and, in some cases, be absorbed into the bloodstream.

What Are the Long-Term Complications of Mercury Intoxication?

A. Neurological Effects:

• Low intelligence and impaired cognitive function.

• Delayed response to stimuli.

• Delayed motor reflexes

• Paralysis and numbness of hands and feet.

• Children may develop symptoms of attention-deficit hyperactivity disorder (ADHD), a common neurobehavioral disorder that affects children.

B. Effects on the Reproductive System:

• Risk of infertility.

• Reduced sperm count in men.

• Fetal exposure causes deformities and reduced general and brain growth.

C. Cardiovascular Effects:

• Increased risk of heart problems like coronary heart disease, heart attack, etc.

How Is Mercury Intoxication Diagnosed?

The diagnosis is confirmed after a clinical examination and laboratory tests. During the clinical examination, the doctor asks for symptoms, dietary habits, work or living environment, etc. Laboratory tests can assess the presence of mercury in blood and urine.

What Is the Treatment for Mercury Intoxication?

The treatment mainly involves eliminating mercury content from the body. There is no cure for this condition, and the treatment is only symptomatic. The clinicians recommend the following:

• The affected person should stop or reduce their consumption of seafood.

• If the toxicity is due to environmental exposure, the patient is asked to move to a safer zone.

• Patients with severe poisoning are given chelation therapy to eliminate metallic mercury. Drugs that bind to heavy metals are used in chelation therapy, thereby facilitating its elimination through urine.

• Treatment can be continued to prevent long-term side effects.

How Can Mercury Intoxication Be Prevented?

Mercury poisoning can be prevented by:

• Limiting seafood intake.

• Following seafood intake guidelines for children and pregnant women.

• Carefully managing mercury spills from the thermometer and CFL bulbs.

• Living in a non-industrial environment.

• If any concerns about mercury fillings try alternative dental fillings suggested by the dentist. However dental amalgam restoration is considered safe by the American Dental Association.

Remember that reducing mercury exposure can be brought about by awareness and a combination of lifestyle factors.

Conclusion:

Mercury intoxication occurs due to chronic or acute exposure to large amounts of mercury through seafood, dental fillings, and inhalation of mercury vapors. Consumption of seafood containing methylmercury is one of the leading causes of mercury toxicity. The symptoms are primarily neurological, including impaired sensory changes, emotional disturbances, seizures, etc. Growing fetuses are the most vulnerable to mercury poisoning. Therefore, the treatment involves symptomatic care and chelation therapy. However, it is always better to take the necessary precautions to prevent mercury toxicity.