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Mercury Toxicity

(Mercury Poisoning)

En Español (Spanish Version)

Definition | Causes | Risk Factors | Symptoms | Diagnosis | Treatment | Prevention

Definition

Mercury toxicity occurs when a person is exposed to mercury. Mercury is a naturally occurring metal. Short- or long-term exposure to mercury can cause serious health problems. If you think you have been exposed to mercury, contact your doctor right away.

Mercury has several forms, including:

  • Metallic mercury—a shiny, silver-white, odorless liquid that becomes a colorless, odorless gas when heated
  • Methylmercury—a chemical made up of mercury combined with carbon; mainly produced by microscopic organisms in the water and soil
  • Mercury salts—white powders or crystals formed when mercury combines with elements such as chlorine, sulfur, or oxygen

Metallic mercury and methylmercury easily reach the brain and are more harmful than mercury salts.

Causes

Mercury toxicity may occur when you are exposed to toxic amounts of mercury due to:

  • Breathing airborne mercury vapors
  • Eating contaminated food, especially fish or shellfish—Larger and older fish tend to have the highest levels of mercury.
  • Drinking water contaminated with mercury (rare)
  • Practicing religious or folk medicine rituals that include mercury

Metallic mercury can be found in consumer products, such as fluorescent light bulbs, batteries, thermostats, and old thermometers. Mercury, combined with other elements, is also found in some types of dental fillings. Research has not shown that this type of filling is harmful to people. Although thimerosol is no longer used in vaccines in the United States, the mercury-containing compound is still used in some countries. Research has not shown that it is harmful to people.

Risk Factors

Anyone can develop mercury toxicity as a result of mercury exposure. Certain people are more likely to be exposed to mercury. The following factors increase your chances of being exposed to mercury. If you have any of these risk factors, tell your doctor:

  • Working in:
    • Dental services
    • Health services
    • The chemical industry
    • Other industries that use mercury
  • Practicing rituals that include mercury
  • Eating over 6 ounces of white albacore tuna per week
  • Eating over 12 ounces a week of fish and shellfish that is considered lower in mercury, such as shrimp, canned light tuna, salmon, pollock, and catfish

In addition, pregnant women, their unborn fetuses, and young children are especially vulnerable to the harmful effects of mercury exposure.

Widespread Toxicity in Infant

Infection in baby true
Fetuses and young children are more vulnerable to the effects of mercury poisoning.
Copyright © Nucleus Medical Media, Inc.

Symptoms

Mercury can cause harmful effects before symptoms develop. It is important to contact your doctor right away if you think you have been exposed to mercury, regardless of your symptoms. When symptoms do develop, they may include:

  • Tremors
  • Changes in vision or hearing
  • Insomnia
  • Weakness
  • Memory problems
  • Headache
  • Nausea
  • Vomiting
  • Diarrhea
  • Rapid heart beat
  • Eye irritation
  • Irritability
  • Shyness
  • Nervousness
  • Breathing problems
  • Painful mouth
  • Abdominal pain
  • Fever and/or chills
  • Difficulty concentrating

Diagnosis

Your doctor will ask about your symptoms and medical history. A physical exam will be done.

Tests may include the following:

  • Blood tests
  • Urine tests
  • Scalp hair analysis

Treatment

Talk with your doctor about the best treatment plan for you. Treatment options include:

Chelation therapy involves putting a chemical, or chelating agent, into the bloodstream. The chelating agent combines with mercury to help remove it from the body. Chelating agents may be given by pill or by injection.

Prevention

To help reduce your chances of getting mercury toxicity, take the following steps:

  • Avoid using metallic mercury for any purpose.
  • If you must use metallic mercury, keep it safely stored in a leak-proof container in a secure space, such as a locking closet.
  • Trade in old thermometers or barometers containing mercury for new ones that do not.
  • Carefully handle and dispose of items containing mercury, such as thermometers and fluorescent light bulbs.
  • Do not vacuum or heat spilled mercury.
  • Teach children not to play with silver liquids.
  • Properly dispose of old medications that contain mercury.
  • Keep mercury-containing medications away from children.
  • Learn about wildlife and fish advisories in your area from your local public health or natural resources department.
  • Limit fish intake to recommended quantities and avoid fish known to be contaminated by mercury:
    • Do not eat shark, swordfish, king mackerel, or tilefish.
    • Eat up to 12 ounces of fish and shellfish considered lower in mercury per week. These fish include shrimp, canned light tuna, salmon, pollock, and catfish.
    • Eat up to 6 ounces of white albacore tuna per week.
    • If you want to eat local fish, check to make sure the water is not contaminated. In general, limit your intake of local fish to 6 ounces.

If you spill a small amount of metallic mercury:

  • Remove children from the area.
  • DO NOT use a vacuum cleaner.
  • Carefully roll the bead of mercury onto a sheet of paper or suck it up with an eyedropper.
  • Place the bead in a bag or airtight container.
  • Contact your local health department to find out how to dispose of the mercury and paper or eye dropper.
  • Ventilate the room to the outside.
  • Use fans to speed ventilation for at least one hour.

Many factors can affect the reliability of lab tests. A test may suggest an illness that actually does not exist. This called a false positive. A test may also miss an illness that actually does exist. This is called a false negative.

A doctor will consider the results from many tests and your symptoms before making a diagnosis. It is important to discuss these results with your doctor before making any conclusions.

RESOURCES:

Agency for Toxic Substances and Disease Registry

Centers for Disease Control and Prevention

http://www.atsdr.cdc.gov

US Environmental Protection Agency

http://www.epa.gov

US Food and Drug Administration

http://www.fda.gov

CANADIAN RESOURCES:

Public Health Agency of Canada

http://www.phac-aspc.gc.ca

References:

Composite filings. American Dental Association's Mouth Healthy website. Available at: http://www.mouthhealthy.org/en/az-topics/c/composite-fillings.aspx. Accessed April 26, 2013.

Harrison’s Principles of Internal Medicine. 16th ed. McGraw Hill; 2005.

Kelly BC, Ikonomou MG, et al. Mercury and other trace elements in farmed and wild salmon from British Columbia, Canada. Environ Toxicol Chem. 2008;27(6):1361-1370.

Oken E, Bellinger DC. Fish consumption, methylmercury and child neurodevelopment. Curr Opin Pediatr. 2008;20(2):178-183.

ToxFAQs for mercury. Agency for Toxic Substances and Disease Registry website. Available at: http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=1195&tid=24. Updated October 19, 2011. Accessed April 26, 2013.

What you need to know about mercury in fish and shellfish. Food and Drug Administration website. Available at: http://www.fda.gov/Food/ResourcesForYou/Consumers/ucm110591.htm. Updated March 29, 2013. Accessed April 26, 2013.

12/10/2010 DynaMed's Systematic Literature Surveillance https://dynamed.ebscohost.com/about/about-us: Vearrier D, Greenberg MI. Care of patients who are worried about mercury poisoning from dental fillings. J Am Board Fam Med. 2010;23(6):797-798.

Last reviewed April 2013 by Lawrence Frisch, MD, MPH; Michael Woods, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.