Introduction
Mercury, also known as quicksilver, is a naturally-occurring metal that is toxic to living organisms. Metallic or elemental mercury — an odorless, shiny, silver-white liquid — is commonly used in thermometers, barometers and fluorescent light bulbs. Metallic mercury is extremely dangerous with a few drops generating enough fumes to contaminate the air in a room. Furthermore, skin contact with the metal results in the absorption of mercury into the blood stream and potential health problems. Mercury poisoning may include the following symptoms:
- muscle weakness
- skin rashes
- mental disturbances such as mood swings and memory loss
- impairment of speech, hearing and peripheral vision
- impairment of coordinated movements such as walking or writing
- numbness and "pins and needles" feeling in the hands, feet and sometimes around the mouth
NIEHS, the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) have studied the physiological effects of Methylmercury , a common form of organic mercury (mercury combined with carbon), on humans via fish consumption. Although fish and shellfish have many nutritional benefits, consuming large quantities of fish increases a person’s exposure to mercury. Pregnant women who eat fish high in mercury on a regular basis run the risk of permanently damaging their developing fetuses. Children born to these mothers may exhibit motor difficulties, sensory problems and cognitive deficits.
To educate the public on mercury’s toxic affects, the FDA and EPA released a consumer advisory in 2004 that recommends that young children, women who are pregnant or who may become pregnant and nursing mothers should avoid fish that contain high levels of methylmercury, such as Shark, Swordfish, King Mackerel and Tilefish. Instead, they should eat up to 12 ounces (two average meals) a week of a variety of fish and shellfish that contain lower concentrations of methylmercury. Five of the most common "low-mercury" fish are shrimp, canned light tuna, salmon, pollock and catfish.
Video from the Dartmouth Superfund Research Program explains how mercury enters the seafood we eat, why eating low-mercury fish is important for good health, and the need to keep mercury out of the environment.
What is NIEHS Doing?
NIEHS Research Efforts
- Brain Benefits of Aerobic Exercise Lost to Mercury Exposure - Cognitive function improves with aerobic exercise, but not for people exposed to high levels of mercury before birth.
- Children's Environmental Health Center - The NIEHS/EPA Children’s Environmental Health and Disease Prevention Research Centers, or Children’s Centers, study how complex interactions between the environment, genetics, and other factors affect children’s health.
- Superfund Research Program: Metals Mixtures - Metals in the environment are commonly found as mixtures. Use these search tools to find additional information about SRP-funded metals research projects.
Further Reading
Stories from the Environmental Factor (NIEHS Newsletter)
- Moderate Fish Intake by Moms Linked to Health Benefits for Kids (May 2020)
- NIEHS-Funded Papers Inform Efforts to Reduce Mercury Pollution (March 2018)
Additional Resources
- EHP Mercury Collection - The identification of mercury's adverse health effects has led to measures to minimize further.
- Indigenous Health Collection- Environmental Health Perspectives (EHP) present a collection of papers focusing on indigenous peoples who overall experience a disproportionate burden of several chronic diseases, compared with other racial and ethnic groups.
- What You Need to Know About Mercury in Fish and Shellfish - FDA and EPA Consumer Advisory
Related Health Topics
For Educators
- Sea Turtle Restoration Project Mercury Calculator - By typing in your weight, selecting a type of fish, and indicating the amount you might eat in a week, this tool, produced by Teachers' Domain, will calculate your estimated mercury exposure. Discussion questions are also included.
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