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As of October 1, 2020, NLM will discontinue the Tox Town website, This change is part of NLM’s initiative to align and consolidate the Library’s consumer health information to make it easier for online health information seekers to find and navigate trusted health information from NLM.

We invite users to visit topics related to environmental health, safety, and toxicology on MedlinePlus, the NLM’s flagship website for health information for patients, families, and the general public. The National Institute of Environmental Health Sciences (NIEHS) also offers related resources that may be of interest: Kids Environment, Kids Health, Health & Education, and For Educators. If you have questions or suggestions, please contact NLM Customer Service.


What is Mercury?

Mercury is a metal that occurs naturally. It comes in several forms, including a shiny, silver-white liquid and a tin-white solid. If it is heated, it becomes a colorless gas. It is emitted from burning coal and waste, and from volcanoes.

Mercury is used in some thermometers, barometers, vapor and fluorescent lamps, fluorescent bulbs, mirror coatings, dental fillings, batteries, cosmetics, and herbal remedies and pharmaceuticals.

Methylmercury is the most common mercury compound. It forms in water and soil and builds up in the tissues of fish.

See also: Factories Food and Cooking Brownfield Power Plants Learning and Developmental Disabilities Reproductive Health

Where is Mercury found?

  • Consumer products - thermometers, barometers, vapor and fluorescent lamps, fluorescent bulbs, mirror coatings, dental fillings, batteries, cosmetics, and herbal remedies and pharmaceuticals
  • Food – fish and shellfish
  • Air – emissions from mercury spills, incinerators, coal-burning power plants, and some industries

How can I be exposed to Mercury?

Mercury commonly enter(s) the body through:


Ingestion (swallowing)

  • Eating fish or shellfish contaminated with methylmercury, swallowing releases of mercury from some dental fillings, or drinking contaminated water

Inhalation (breathing)

  • Breathing mercury vapors from spills, incinerators, coal-fired power plants, and industry emissions

Skin contact

  • Touching liquid mercury or products made with mercury

What happens when I am exposed to Mercury?

Exposure to high levels of mercury can cause mercury poisoning.

Short-term exposure to high levels of mercury can cause:

  • Lung irritation and damage
  • Nausea and vomiting
  • Diarrhea
  • Increased blood pressure
  • Loss of coordination
  • Numbness
  • Skin rashes
  • Eye irritation

Long-term exposure to high levels of mercury can cause:

  • Brain and kidney damage
  • Damage to a developing fetus
  • Tremors and numbness
  • Changes in vision or hearing
  • Memory problems
  • Muscle weakness
  • In children exposed to mercury during pregnancy, motor and cognitive difficulties, and sensory problems

Chronic poisoning by methylmercury can lead to death.

Who is at risk for exposure to Mercury?

  • Consumers
    • Some consumer products and foods contain mercury.
  • Pregnant and nursing women
    • Exposure can damage a developing fetus and pass into breast milk.
  • Subsistence fishers and their families
    • People who rely on subsistence fishing may eat more contaminated fish.

Reduce your risk

If you think your health has been affected by exposure to mercury, contact your health care professional. 

Always wash your hands thoroughly after handling chemicals. For poisoning emergencies or questions about possible poisons, please contact your local poison control center at 1-800-222-1222.

  • Does your thermometer contain mercury?
  • Do you use fluorescent lamps or light bulbs?
  • Do you use medicines that contain mercury?
  • Do you eat a lot of fish that may contain mercury?
  • Carefully handle and dispose of products that contain mercury, such as thermometers or fluorescent light bulbs.
  • Do not touch or vacuum spilled mercury.
  • If a large amount of mercury has been spilled, contact your health department immediately.
  • Properly dispose of older medicines that contain mercury.
  • Learn about wildlife and fish advisories in your area from your public health or natural resources department.
  • Eat low-methylmercury fish such as shrimp, canned light tuna, salmon, pollock, and catfish.
  • Avoid or limit eating fish that contain high levels of methylmercury, such as shark, swordfish, king mackerel, and tilefish.
  • Teach children not to play with shiny, silver liquids.
  • Keep children away from all mercury-containing medicines and products.
  • Pregnant women and children should avoid rooms where liquid mercury has been used.
  • Young children, women who are pregnant or who may become pregnant, and nursing mothers should avoid eating fish that contain high levels of methylmercury.

National Library of Medicine Resources and Databases

  • Mercury: Health Information Resources
    Health resources in English and Spanish on mercury, including background information; law, regulations and policy; specific aspects, topic-related searches of National Library of Medicine; and blogs, news, podcasts, and videos.
  • Mercury Compounds. Hazardous Substances Data Bank
    Search results on mercury compounds from a toxicology database that focuses on the toxicology of potentially hazardous chemicals.
  • Mercury, Inorganic Compounds. Haz-Map
    Information about inorganic mercury compounds from an occupational health database designed for health and safety professionals and consumers seeking information about the adverse effects of workplace exposures to chemical and biological agents.

Additional Resources

  • Protect Yourself from Mercury in Your Well Water
    North Carolina Department of Health and Human Services
    Factsheet with answers to the most frequently asked questions about mercury in well water, including information about associated hazardous health effects, testing for unsafe levels of mercury, actions you can take to protect yourself, and links to additional information.
  • Mercury and Health
    World Health Organization
    Information on the adverse health effects associated with mercury exposure, as well as activities for reducing human exposure from mercury sources, and links to additional resources.
  • Mercury
    National Institute of Environmental Health Sciences
    Information on mercury, including symptoms of mercury poisoning, and links to additional resources and related health topics for consumers and educators from a federal institute that investigates the interplay between environmental exposures, human biology, genetics, and common diseases to help prevent disease and improve human health.
  • Mercury. ToxFAQs
    Agency for Toxic Substances and Disease Registry
    Factsheet with answers to the most frequently asked questions about mercury exposure and its effect on human health, developed by a federal public health agency that protects communities from harmful health effects related to exposure to natural and man-made hazardous substances.
  • Mercury In Your Environment
    Environmental Protection Agency
    Links to resources on mercury exposure, including products containing mercury, as well as actions and programs to reduce mercury in the environment.

Science Classroom (Grades 6-8)

Enhance your education on toxic chemicals in our environment using lesson plans, games and activities, videos, informational websites, and more.

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National Library of Medicine
An animation about mercury, where it is found, how it is used, and the effects on human health.
Mercury-Middle School Activities
Environmental Protection Agency
Activities for middle school students about mercury in the environment, in schools, and at home.
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