Exposure to high levels of mercury can harm the brain, heart, kidneys, lungs, and immune system of people of all ages. Very young children and unborn are the most susceptible to the effects of mercury. Although mercury is known to cause tumors in rats in the laboratory, there is insufficient proof to link mercury with cancers in humans.
Mercury is a toxic heavy metal that is widely dispersed in nature. Most human exposure results from fish consumption or spillage.
There are three different forms of mercury that cause health problems:
Elemental mercury: It is a shiny, silver-white liquid used in thermometers, dental fillings, light bulbs, and other products. Breathing in enough elemental mercury will cause symptoms right away. Symptoms include:
- Swollen or bleeding gum
- Difficulty breathing
- Metallic taste in the mouth
- Bad cough
- Permanent lung damage (rare)
- Mood swings, irritability
- Neuromuscular changes (such as weakness, muscle atrophy, and twitching)
- Abnormal sensations such as pins and needles
- Poor higher mental functions such as writing, speech, and interpretation
- Higher exposures may also cause kidney effects, respiratory failure, and death
Inorganic mercury: They are compounds or salts that result when mercury combines with other elements such as chlorine, sulfur, or oxygen. Inorganic mercury is usually poisonous. Symptoms include:
- Burning in the stomach and throat
- Bloody diarrhea and vomiting
- Kidney damage
- Blood or fluid loss leading to death (rare)
Organic mercury: These are compounds that result when mercury combines with carbon. The most common is methyl mercury, which is usually produced by microscopic organisms in the water and soil. Methyl mercury poisoning may also happen through fish intake, although in most people, fish consumption may not lead to very high mercury levels in the body. Organic mercury causes problems over years or decades, not right away. This means that being exposed to small amounts of organic mercury every day for years will likely cause symptoms to appear later. Methyl mercury is a neurotoxin, and it affects the brain and nerves. Symptoms include:
- Loss of peripheral vision
- "Pins and needles" feelings, usually in the hands, feet, and around the mouth
- Lack of coordination of movements
- Impairment of speech, hearing, walking
- Muscle weakness
- Numbness or pain in certain parts of your skin
- Uncontrollable shaking or tremor
- Inability to walk well
- Blindness and double vision
- Memory problems
- Seizures and death (with large exposures)
Other common symptoms of mercury poisoning include:
What's the difference between having mercury exposure and mercury poisoning?
Mercury exposure: A person with no symptoms and no changes physically or chemically may have a high mercury level. It doesn’t become poisonous under the true definition unless someone has had physical or chemical changes in their body. That doesn’t mean it's safe to have levels without symptoms. Over time, even if they are exposed at low levels, the symptoms may not manifest until weeks or months later.
How is mercury poisoning usually treated?
The goal of treating mercury poisoning is to remove exposure and decontaminate the patient.
- Patients may be placed on intravenous fluids and oxygen therapy depending on the type of exposure.
- Gastrointestinal (GI) decontamination and whole bowel irrigation may be attempted.
- Activated charcoal and chelation may be initiated early in mercury exposure cases because it may reduce toxic effects.
- Inorganic mercury and elemental mercury can be treated with an initial course of intramuscular dimercaprol and then followed by oral succimer.
- Hemodialysis is usually preferred for patients with renal damage. In addition, exchange transfusions may also be attempted.
What is the outlook in patients with mercury poisoning?
Mercury toxicity can be very difficult to identify with multisystem involvement. Symptoms of mercury exposure and toxicity can easily be misdiagnosed as normal medical problems such as gastritis, gastrointestinal (GI) bleeding, and respiratory distress. A keen awareness leading to early identification and treatment is critical due to severe and potentially irreversible damage. The outlook for mercury exposure is highly variable but is dependent on the level of exposure. Significant exposures can lead to coma and death. Minor symptoms may resolve over time. Neurologic symptoms that can be delayed in the presentation may persist for decades. High exposures may lead to death, permanent neurologic deficits, or mental retardation. For adults, mercury poisoning is usually a reversible problem. The body can rid itself of mercury if the exposure to mercury is halted. Symptoms such as fatigue and memory problems seem to go away as mercury levels decrease. However, for children and developing fetuses, mercury poisoning can cause long-term neurological problems. Mercury exposure before birth has been linked to lower intelligence and delays in learning motor skills.