Environmental and health effects of mercury
How are we exposed to mercury?
People are most often exposed to mercury by eating fish and shellfish that contain methylmercury. You can also be exposed if you breathe mercury vapors from contaminated air, in workplaces or in areas where products that contain mercury have broken (such as thermometers, thermostats, or fluorescent light bulbs). You can also be exposed through skin contact with mercury or use mercury-containing products such as some skin-lightening creams.
How much fish is okay to eat?
Fish is good for you and part of a healthy diet. Use the healthy fish guide (external link) to find out how much fish you can safely eat. The amount of fish that is safe to eat depends on several factors: the type of fish, its age, where it is caught, and the body weight of the person eating it.
How does mercury get into the environment?
Activities such as burning coal for fuel or for manufacturing release mercury into the air. When products and wastes containing mercury are improperly disposed, mercury is released into the air, ground or water. Mercury is also in the environment from natural sources, such as rocks, soil and volcanoes. Mercury is persistent in the environment --it never breaks down or goes away. Bacteria living at the bottom of lakes, rivers and the ocean turn mercury into methylmercury. Methylmercury concentrates in fish, then birds and mammals, including humans, who eat those fish.
Infants and children
Children, including unborn babies, are most vulnerable to mercury poisoning because their developing brains and nervous systems are sensitive to low-doses of methylmercury. Exposure to methylmercury can affect thinking, memory, attention, language, fine motor skills and visual-spatial abilities (e.g., drawing).
Pregnant women and their fetus
The Washington State Department of Health advises pregnant women to eat a variety of fish that are low in mercury (external link) and to avoid fish that is high in mercury. This is because infants may be exposed in the womb and through breastfeeding.
Mercury poisoning symptoms in adults
In adults, exposure to methylmercury affects the nervous system. Symptoms can include
- Loss of peripheral vision
- Disturbing sensations (‘pins and needles’ feeling)
- Problems speaking
- Lack of coordination and
- Muscle weakness.
Contact the Washington Poison Center (External link) at 1-800-222-1222 if you think you may have symptoms of mercury exposure or if you have other questions about mercury poisoning.
Resources
- Washington fish consumption advisories (Washington State Department of Health) provides informationabout eating fish and shellfish caught in specific Washington State water bodies.
- A statewide mercury advisories for fish (Washington State Department of Health) provides information about eating freshwater fish caught in Washington State, commercial predator fish like shark and swordfish, and canned tuna.
- "Fish Facts for Good Health" (Washington State Department of Health) provides information about mercury and fish and is available in many languages.
Find more information on how mercury enters the environment and its health impacts (Environmental Protection Agency) - The Washington State Mercury Chemical Action Plan (Washington State Department of Ecology, 2003) describes the sources of mercury pollution in Washington State and outlines strategies for reducing this pollution.
- The Centers for Disease Control and Prevention describes the health impacts from exposure to mercury.
