Mercury Poisoning
Illness from exposure to the toxic metal mercury
Quick Facts
- Type: Heavy metal poisoning
- Common sources: Contaminated fish, mercury vapor, some products
- Main targets: Nervous system and kidneys
- Seek urgent care: Spills, swallowing, or severe symptoms
Overview
Mercury poisoning occurs when the body takes in more mercury than it can safely handle. Mercury is a naturally occurring metal that exists in several forms, and each affects the body differently. The form matters a great deal for how someone is exposed and what harm results.
The main forms are elemental (metallic) mercury, a silvery liquid that gives off a toxic vapor; inorganic mercury, found in some older products and industrial settings; and organic mercury, especially methylmercury, which builds up in fish and shellfish. Mercury chiefly damages the brain and nervous system and the kidneys. Poisoning can be sudden after a large exposure or develop slowly from repeated smaller exposures.
Symptoms
Symptoms depend on the form of mercury, the amount, and how long the exposure lasted. Common features include:
- Numbness or tingling in the hands, feet, or around the mouth
- Tremors and trouble with coordination or walking
- Muscle weakness
- Changes in vision, hearing, or speech
- Memory problems, irritability, anxiety, or mood changes
- Skin rashes and, with metallic mercury vapor, cough and breathing trouble
Inhaling a large amount of mercury vapor can cause severe lung irritation and breathing difficulty and is a medical emergency. In unborn babies and young children, organic mercury can interfere with brain and nervous system development even at lower exposures.
Causes
People become exposed to mercury through several routes:
- Eating contaminated fish: The most common everyday source, as methylmercury builds up in large, long-lived fish.
- Breathing mercury vapor: From broken thermometers or fluorescent bulbs, certain industrial work, and gold mining.
- Skin contact or swallowing: From some traditional remedies, skin-lightening creams, and older products containing mercury.
- Occupational exposure: In some manufacturing, mining, and laboratory settings.
Dental fillings that contain mercury are generally considered to release only very small amounts and are not a typical cause of poisoning.
Risk Factors
- Frequent eating of large predatory fish such as certain tuna, shark, swordfish, and king mackerel
- Jobs in mining, manufacturing, or industries that use mercury
- Use of unregulated skin-lightening creams or some traditional remedies
- Living near certain industrial sources of mercury
- Pregnancy and early childhood, when the developing brain is especially sensitive
Diagnosis
Diagnosis combines a history of possible exposure with laboratory testing:
- Exposure history: Questions about diet, occupation, hobbies, products used, and any spills or accidents.
- Blood tests: Useful mainly for recent organic mercury exposure, such as from fish.
- Urine tests: Helpful for elemental and inorganic mercury exposure.
- Neurological assessment: Checking coordination, sensation, strength, and mental function.
Because some symptoms overlap with other conditions, the link to mercury often comes from recognizing the exposure rather than from the symptoms alone.
Treatment
The first and most important step is to stop the exposure. Further treatment depends on how severe the poisoning is and which form of mercury is involved.
- Removing the source: Changing diet, leaving the contaminated environment, or safely cleaning up a spill.
- Supportive care: Managing breathing, fluids, and other body systems, especially after a large exposure.
- Chelation therapy: Medications that bind mercury and help the body remove it, used in selected cases of significant poisoning under specialist supervision.
- Monitoring organs: Watching kidney and nervous system function over time.
Some nervous system effects, particularly from heavy or prolonged exposure, may improve slowly or only partially even after the mercury is removed, which is why preventing exposure is so important.
Prevention
- Follow local fish advisories and limit large predatory fish, especially during pregnancy
- Choose lower-mercury fish such as salmon, sardines, and shrimp when eating fish often
- Clean up broken mercury thermometers or bulbs carefully and ventilate the area; never vacuum a spill
- Avoid skin-lightening creams and remedies that may contain mercury
- Use proper safety measures and protective equipment in jobs that involve mercury
When to See a Doctor
See a doctor if you have ongoing numbness, tremor, coordination problems, memory changes, or other unexplained symptoms and a possible source of mercury exposure. Seek emergency care or contact a poison control center right away if someone swallows mercury, a large spill occurs in an enclosed space, or a person develops sudden breathing difficulty, severe weakness, or collapse after exposure.
Frequently Asked Questions
Can you get mercury poisoning from eating fish?
Yes. Some fish, especially large predatory species, contain methylmercury that builds up in the body over time. Eating large amounts regularly can lead to poisoning, which is why pregnant people and young children are advised to limit high-mercury fish.
Are mercury dental fillings dangerous?
Mercury-containing (amalgam) fillings release only very small amounts of mercury and are generally considered safe for most people. They are not a typical cause of mercury poisoning, though concerns can be discussed with a dentist.
What should I do if a mercury thermometer breaks?
Ventilate the area, keep people and pets away, and carefully collect the beads without touching them directly. Never use a vacuum cleaner, which spreads the vapor. Seal the material in a container and follow local hazardous waste guidance.
Can mercury poisoning be cured?
Stopping the exposure is the key step, and mild cases often improve over time. Significant poisoning may be treated with chelation medicines that help remove mercury, but some nervous system damage from heavy exposure can be lasting.
What are the first signs of mercury poisoning?
Early signs often include numbness or tingling in the hands, feet, or around the mouth, along with tremor, coordination problems, and changes in mood or memory. Symptoms can develop gradually with repeated exposure.
References
- World Health Organization (WHO). Mercury and health.
- Agency for Toxic Substances and Disease Registry (ATSDR). Mercury.
- U.S. Environmental Protection Agency (EPA). Mercury.
- MedlinePlus, U.S. National Library of Medicine. Mercury.