What are the other Names for this Condition? (Also known as/Synonyms)

• Chronic Heavy Metal Poisoning - Mercury
• Chronic Mercury Toxicity
• Chronic Poisoning due to Mercury

What is Chronic Mercury Poisoning? (Definition/Background Information)

• Chronic Mercury Poisoning occurs from long-term exposure to the element mercury and its associated products. The exposure may occur from inhalation of mercury vapors and fumes, ingestion of mercury, or through skin/dermal contact
• Mercury (Hg) has a wide variety of industrial applications. It is grouped as a heavy metal and is the only ‘liquid’ metal available at room temperature. It is found all over the world - in the air, water, and soil (including in rocks)
• The source of mercury exposure may be wide-ranging and includes exposure to volcanic ashes, coal-based power station fumes, consumption of contaminated fish, use of various medications (such as laxatives and antimicrobial drugs), etc.
• The signs and symptoms of Chronic Mercury Poisoning include fever and chills, peripheral neuropathy, vomiting and diarrhea, renal failure, and irritability. The condition is diagnosed by complete medical history and physical exam, and through tests to establish the levels of mercury in the body
• Chronic Mercury Poisoning is generally treated by removing the affected individual from the source of exposure and through symptomatic treatment. The prognosis depends on several factors including the health condition of the individual and when he/she is removed from the source of toxicity

Who gets Chronic Mercury Poisoning? (Age and Sex Distribution)

• Individuals of a wide age range can be affected by Chronic Mercury Poisoning, which includes children and adults. However, individuals who are frequently exposed to mercury may be affected the most
• Both males and females are affected and no particular preference is observed
• The condition can affect all races and ethnic groups

What are the Risk Factors for Chronic Mercury Poisoning? (Predisposing Factors)

The major risk factors associated with Chronic Mercury Poisoning is exposure conditions. Exposure to the chemical compound may occur from the following main sources:

• Exposure to toxic fumes from volcanic eruptions and from other natural geological phenomena. These events account for nearly half of the toxic mercury vapors released into the atmosphere
• Coal-driven power plants release residual mercury-based vapors; this factor accounts for up to 25% of all mercury released into the environment
• Use of mercury to separate gold from silt and other ore compounds (practiced worldwide) through a process that involves boiling the mercury-based mixture, thus releasing toxic mercury fumes into the atmosphere

Exposure to mercury may also occur from the following sources:

• Consumption of fish (including shellfish) and aquatic plant that contain mercury (in the form of methylmercury): Organic form of mercury is present in the food chain. Very tiny aquatic fauna, called plankton that contains mercury, are consumed by small fish that are then consumed by large fish. The accumulation of mercury in the food chain is termed biomagnification
• Industrial exposure occurs when mercury is used as catalyst, or as part of an industrial product; industrial pollution
• Coal burning for cooking and heating of homes
• During disposal of fluorescent bulbs
• Some cosmetics have mercury, to lighten skin color
• Use of amalgams for dental works
• Certain antimicrobial medications
• Laxatives and diuretics containing the causative compounds
• Diaper rinse solutions
• Batteries for watches
• Antiseptic creams
• Teething powders

Note: It is important to note that some of the above products/compounds were risk factors prior to stringent governmental regulations regarding mercury and other heavy metal use were in place.

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one's chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Chronic Mercury Poisoning? (Etiology)

The cause of Chronic Mercury Poisoning is generally due to a long-term exposure through inhalation of fumes/vapors, oral ingestion, or skin contact. Exposure to mercury, in a pure form or as part of an organic/inorganic compound or salt, through ingestion or inhalation can result in toxicity.

• Exposure may be through a variety of compounds or environmental conditions and even small-to-tiny amounts of exposure can result in signs and symptoms
• The severity of poisoning is dictated by the duration and intensity of exposure, the form and route of exposure, and the health status of the affected individual
• 80% of inhaled mercury is absorbed by the lungs; liquid mercury and mercury vapor is odorless
• Exposure to pure forms of liquid mercury is termed elemental (or metallic) mercury poisoning
• Babies in the womb and individuals, who have certain medical conditions that affect the liver, kidney, or other vital organs, have a higher risk for severe signs and symptoms
• Genetic sensitivity to heavy metal poisoning has also been noted

What are the Signs and Symptoms of Chronic Mercury Poisoning?

The signs and symptoms of Chronic Mercury Poisoning depend on whether the exposure occurred through oral ingestion, chronic inhalation, or skin contact. It also depends on the source and dose of exposure. The signs and symptoms vary from one individual to another.

General signs and symptoms associated with Chronic Mercury Poisoning include:

• Any part or system of the body may be affected
• There can be fever, chills, nausea and vomiting, diarrhea, neuropsychiatric signs and symptoms including irritability, anxiety, mood swings, etc.
• The signs and symptoms may also include cough, sore throat, abdominal pain, metallic taste in mouth, headache, visual disturbances, chest pain, swallowing difficulties, etc.
• Elemental mercury can cause dermatitis (inflammation of the skin) and itching of eyes

In comparison to adults, because children have a larger lung surface in relation to their body, exposure to the same dosage of mercury results in significant signs and symptoms in children.

Skin-related signs and symptoms may include:

• Pinkish discolored skin of the hands and feet, and also on the tip of the nose (due to an allergic reaction of the skin to the chemical)
• Pain, burning or itching sensation due to peripheral neuropathy
• Loss of superficial layers of skin - a process called desquamation
• Skin rashes that come and go
• Ulcers on the gums

Other signs and symptoms of Chronic Mercury Poisoning may include:

• Increased heart rate (tachycardia) and increased blood pressure
• Lack of coordination or ataxia
• Excess saliva production; being excessively thirsty (polydipsia)
• Difficulty in seeing bright light or photophobia
• Loss of memory
• Loss of sleep, difficulty in sleeping
• Children can become cranky and show aggressive behavior
• Difficulty in speaking/learning

How is Chronic Mercury Poisoning Diagnosed?

A diagnosis of Chronic Mercury Poisoning may involve the following tests and procedures:

• A complete physical examination and comprehensive medical history evaluation (including procuring information on exposure to heavy metals)
• Mercury testing: It is used to examine the levels of mercury in blood, urine, and rarely, in hair
• Complete blood count
• Liver function tests
• Blood urea nitrogen (BUN) test
• Creatinine test
• Nerve conduction studies

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis. 

What are the possible Complications of Chronic Mercury Poisoning?

The complications of Chronic Mercury Poisoning could include:

• Functioning of the immune system, nervous system, and digestive system can be severely compromised
• Fluid accumulation in lung can lead to lung failure, which can be fatal
• Acute kidney failure
• Severe liver damage
• Potential birth defects in pregnant women; it may lead to spontaneous abortions
• Longstanding exposure can result in decreased academic performance; it can affect one’s work
• Skin sensitization through chronic skin exposure resulting in skin abnormalities
• Gastrointestinal complications including diarrhea and vomiting with blood due to prolonged exposure
• Electrolyte imbalances can result in severe damage to vital organs
• Mercury has been shown to be a potential carcinogen in animals (based on animal model studies), but not definitely proven in humans
• A few diseases that arise from mercury poisoning include acrodynia (pink disease), Hunter-Russell syndrome, and Minamata disease

Coma and death can result from ingestion of heavy metals.

How is Chronic Mercury Poisoning Treated?

The treatment for Chronic Mercury Poisoning is determined based on the severity of the symptoms and the mode of toxic exposure. There is no antidote to mercury poisoning. The most important treatment measure is removing the individual from the source of exposure and preventing further exposure to the toxic material.

• Symptomatic treatment that may require hospitalisation may involve the following:
  • Immediately washing the body and eyes, if exposure is through skin
  • Control of blood pressure
  • Short-term dialysis for kidney failure
  • Provide breathing support
• Chelation therapy
• Any underlying complication may have to be treated on a case-by-case basis
• For exposure through skin contact, the following treatment measures may be employed:
  • Removal from the toxic source of exposure
  • Flushing of the eyes with water, if the eyes or skin are acutely exposed
  • Antibiotic creams to avoid secondary infections in skin ulcers
• For exposure due to oral ingestion, the following treatment measures may be employed:
  • Fluids and electrolytes may be administered to maintain electrolyte balance
  • The ingested element/chemical may be passed out through bowel movement or urine
• For exposure through inhalation, the following treatment measures may be employed:
  • The primary goal is to remove the affected individual from the source of exposure
  • If the lungs are damaged, then breathing assistance (or oxygen) is provided

Note: Activated charcoal is not an effective treatment for mercury poisoning.

How can Chronic Mercury Poisoning be Prevented?

Chronic Mercury Poisoning may be prevented by eliminating exposure to sources of mercury. The following points may be considered towards preventing poisoning by mercury and mercury-based compounds.

• Regularly shower and change clothes after industrial work. Avoid bringing home contaminated clothes from the work site
• Practice proper hand hygiene by washing hands with soap frequently
• Ensure that industrial safety regulations for heavy metal exposure is adhered to at workplaces
• Use of respiratory masks, clothing to protect skin, etc. in an industrial setup

Presently, there are many governmental regulations and limitations with respect to the use of mercury in various products, which has helped control the incidence of chronic toxicity due to mercury.

What is the Prognosis of Chronic Mercury Poisoning? (Outcomes/Resolutions)

• The prognosis for Chronic Mercury Poisoning is dependent upon the following factors:
  • The age and health condition of the child/adult
  • The time length and severity of exposure
  • The form of exposure - whether inhaled, swallowed, or through contact with skin
  • The type of mercury product involved - whether in pure form, or as an organic or inorganic compound
• The sooner the individual is removed from the potential source of toxic compound, the better is the prognosis. The prognosis is also dependent upon the amount of heavy metal one is exposed to. Individuals, who are exposed to large amounts of toxic metals orally or through inhalation for longer durations, may have worse prognosis
• With prompt diagnosis and appropriate treatment, individuals who have been acutely exposed to the mercury compounds generally have excellent prognosis and a complete recovery may be possible. However, it is important to note that the signs and symptoms do not get better immediately, but slowly with time

Additional and Relevant Useful Information for Chronic Mercury Poisoning:

Acrodynia is a rare condition that is typically seen in infants and young children resulting from exposure to a variety of heavy metals (commonly to mercury and mercury-based compounds). It results in pinkish discoloration of the skin on the hands and feet.