Mercury is a naturally occurring metal, a useful chemical in some products, and a potential health risk. The chemical element symbol for mercury is Hg. Mercury exists in several forms – the types people are usually exposed to are methylmercury and elemental mercury. Elemental mercury at room temperature is a shiny, silver-white liquid, which can produce a harmful odorless vapor. Methylmercury, an organic compound, can build up in the bodies of long-living, predatory fish. To keep mercury out of the fish we eat and the air we breathe, it's important to take mercury-containing products to a hazardous waste facility for disposal.
How You Can Be Exposed
- Eating mercury-contaminated fish is the primary way people are exposed to mercury. Learn more about mercury in fish and which fish to avoid.
- Inhaling mercury vapor from mercury spills, broken fluorescent bulbs, and air pollution.
- Skin absorption through contact with liquid mercury or mercury-containing creams and ointments.
- Religious, ritual, or folk medicine use of elemental mercury – typically sold under the name "azogue" but may also be labeled as "vidajan" or "quicksilver."
- Some influenza vaccines contain thimerosal, a mercury preservative used to prevent contamination of vaccines.
- Dental amalgam fillings combine elemental mercury with other metals.
Almost all people have trace amounts of mercury in their tissues, reflecting mercury's widespread presence in the environment and people's exposure through eating fish that contain methylmercury. Factors that determine how severe the health effects are from mercury exposure include:
- Form of mercury (such as methylmercury from eating fish or elemental mercury from broken fluorescent light bulbs).
- Dose (how much a person is exposed to).
- Health and age of the person (the fetus is the most susceptible).
- Route of exposure (inhalation, ingestion, skin contact).
Methylmercury Health Effects
For fetuses, infants, and children, the primary health effect of methylmercury is impaired neurological development. Pregnant women who eat mercury-contaminated fish may damage their baby's growing brain and nervous system. Impacts on cognitive thinking, memory, attention, language, and fine motor and visual spatial skills have been seen in children exposed to methylmercury in the womb. See our fish advice for women and children.
Elemental Mercury Health Effects
Liquid elemental mercury primarily causes health effects when it is inhaled as a vapor. These exposures can occur when elemental mercury is spilled or products that contain mercury break and release vapors into the air – this is especially a problem in warm or poorly-ventilated indoor spaces. Symptoms of inhaling mercury vapors can include nausea, respiratory problems, tremors, numbness in the fingers and toes, loss of muscle control, memory loss, kidney disease, and heart problems. Some of these effects can be reversible if the exposure stops, however, memory problems can be permanent.
Mercury and Cancer
There is no human data that indicates exposure to any form of mercury causes cancer, but human data is very limited. Studies have shown that, at high doses, mercury can cause tumors in rats and mice. EPA's 2005 cancer guidelines say neither inorganic mercury nor methylmercury from environmental exposures is likely to cause cancer in humans.
You Can Be Tested
A simple hair, blood, or urine test can determine the level of mercury stored in your body. If you are concerned, talk to your health care provider to request this test.
Products That Contain Mercury
Common products sold today that contain small amounts of mercury include fluorescent lights and button-cell batteries. Mercury thermometers can't be sold anymore in Washington, but having been around for years, they still turn up. Older homes may have mercury thermostats, which are not a health concern if they are unbroken and in good working condition. See EPA's list of products that may contain mercury.
The state's Mercury Education and Reduction Act banned the sale of mercury-containing thermometers, manometers (such as barometers or blood pressure gauges), and novelty items like toys, games, or jewelry. All mercury-containing light bulbs and lamps must have the "Hg" label and instruct consumers on proper disposal. State government must purchase products containing little or no mercury. Schools may no longer purchase elemental mercury or mercury compounds and have removed and properly disposed of around 2,600 pounds of mercury.
Fluorescent Light Bulbs
Fluorescent lights become preferred over incandescent light bulbs because of their energy efficiency and longer lifespan. The downside of fluorescent light bulbs is they contain mercury. LED bulbs are now the preferred light source in most situations because of their increased energy efficiency, longer lifespan, less radiating heat, and they don't contain mercury.
All mercury-containing products, such as old mercury thermometers, thermostats, fluorescent lights, and containers of elemental mercury are considered hazardous and must be properly disposed of at a hazardous waste facility. Broken fluorescent bulbs, mercury thermometers, and the materials used to clean up the spill should also be taken to a hazardous waste facility. Use 1-800-RECYCLE (1-800-732-9253) to find your nearest hazardous waste collection site. To prevent spills or leaks, use extreme caution when packaging and transporting a container of elemental mercury or a product that contains mercury.
How to Handle a Mercury Spill or Release
Everyone should leave the area if mercury is spilled or a product that contains mercury breaks. Don't let anyone walk through the mercury spill on their way out. Open outside doors and windows to vent mercury vapors. Different types of mercury spills require different responses. Follow the EPA information below.
What to do if a:
- Fluorescent bulb or other mercury-containing light bulb breaks.
- Thermometer breaks.
- More than the amount in a thermometer, but less than two tablespoons (one pound) is spilled.
- For large spills of mercury (more than two tablespoons or one pound), have everyone leave the area immediately and call the National Response Center at 1-800-424-8802. The National Response Center hotline operates 24 hours a day, 7 days a week.
Content Source: Environmental Toxicology Program