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Environmental Health Division
Mercury is a naturally occurring element found in rocks, soil, water, air and living things. It is also found in some products. Exposure to mercury can cause health effects. Mercury exists in several forms:
- Elemental Mercury: In its pure form (often called metallic or elemental), mercury is a shiny, silver-white, odorless liquid. Elemental mercury has been used in a wide variety of equipment and consumer products, such as thermometers and certain types of light bulbs. Elemental mercury that is not in a closed container will slowly give off toxic vapor that can accumulate in indoor air. In a warm environment (like a kitchen or on a hot plate) it will vaporize more quickly.
- Methyl Mercury: In the environment, certain bacteria change elemental mercury to methyl mercury, which then accumulates in algae eaten by fish. Older fish and those that feed on other fish have higher amounts because methyl mercury builds up in their bodies. Methyl mercury is the form that people encounter most often.
- Other Forms of Mercury: Mercury naturally occurs in the environment in a salt form or in rock, such as cinnabar. In the past, mercury compounds have been used in some products including fungicides, antiseptics or disinfectants. Some traditional medicines, such as skin lighteners or freckle creams, can contain high levels of mercury.
Breathing: The greatest danger from elemental mercury is through breathing in mercury vapor. When elemental mercury is spilled or exposed to the air, it vaporizes slowly. Mercury vapor breathed into a person’s lungs quickly enters blood and is carried to the brain. If a person is exposed for a long enough time, even a small amount in the air can affect his or her health.
Eating: People are exposed to methyl mercury most often through eating. If someone eats contaminated fish on a regular basis, mercury concentrations can be high enough to pose a risk to their health. If someone swallows the elemental form of mercury, very little is absorbed through the stomach and intestines into the bloodstream.
Skin contact: Exposure to mercury through skin contact can occur when using products such as skin-lightening creams that are made with mercury compounds. However, if someone comes in contact with elemental mercury, very little is absorbed through skin.
Health effects from exposure
Exposure to mercury through the pathways above can damage the central nervous system, kidneys, and liver. Factors that determine how mercury affects a person's health include:
- how much mercury gets into the body,
- how often they are exposed to mercury,
- what other chemicals they are also exposed to, and
- their overall health.
The effects of mercury exposure can range from none to severe. High-level, short-term exposure can cause skin rashes, diarrhea, and respiratory distress. Low-level, long-term exposure can cause muscle tremors, irritability, personality changes, or rashes. Nerve damage from mercury may start with a loss of sensitivity in hands and feet, difficulty in walking, or slurred speech. In rare cases, it has caused paralysis and even death.
Young children (under 15 years old) and fetuses are more sensitive to mercury. Too much mercury can cause lasting problems with understanding and learning. For that reason, pregnant women and women of child-bearing age should avoid mercury exposure.
The best way to avoid exposure to mercury is to not have any mercury in the house. The following are actions you can take to protect yourself and your family from being exposed to mercury:
- Replace any mercury thermometers with digital thermometers or alcohol (red bulb) thermometers.
- Replace old thermostats that contain mercury with non-mercury electronic thermostats.
- Use the steps in How to Clean up a Spill or Broken CFL to clean up small mercury spills.
- Properly dispose of thermometers, thermostats, fluorescent bulbs or tubes, and other devices that contain mercury by taking them to your county’s household waste collection site. Use the Minnesota Pollution Control Agency's webpage to Find your household hazardous waste collection site. The EPA has a list of Mercury in Consumer Products.
- Fish are an excellent source of low fat protein, omega 3 fatty acids, and other nutrients. If you follow the Minnesota Department of Health’s advice, methyl mercury in fish you eat will be safely eliminated between meals. For advice on how to choose which fish to eat and how often, see Statewide Safe-Eating Guidelines.
- Do not use skin lightening creams that contain mercury (some are sold at ethnic markets). Using such products can expose people, particularly breastfeeding infants and young children, to the harmful mercury compounds. The MDH webpage Skin Lightening Products provides more information. Talk to your doctor if you are not sure.
- You and your family may also encounter mercury in schools. For more information, visit the Agency for Toxic Substances and Disease Registry's Don't Mess with Mercury webpages.
Small quantities of mercury spilled in the home should be cleaned up properly so people don’t come in contact with it or breathe its vapors. Some ordinary cleanup measures, such as sweeping and vacuuming, are not appropriate and will likely increase health risks.
The Minnesota Pollution Control Agency provides steps for Cleaning up home mercury spills (PDF). You should NOT attempt to clean up spilled mercury yourself, unless the amount spilled is no more than what is contained in a fever thermometer or compact fluorescent bulb (CFL) and the spill did not occur in a warm environment.
For advice about cleaning up a mercury spill in your home, contact the Minnesota Duty Officer Program at 651-649-5451 or 1-800-422-0798. The duty officer is open 24 hours a day, seven days a week.
The infrequent exposure to mercury from a broken CFL will not affect your health; however, broken CFLs do need to be cleaned up properly to limit any exposure to mercury.
To clean up a broken CFL, follow these steps:
- Step 1: Open the window to allow fresh air into the room to dilute the mercury vapor. When a CFL breaks, some of the mercury it contains turns to vapor immediately. A brief, one-time exposure to this level of mercury vapor is not a health concern.
- Step 2: Use stiff paper or cardboard to collect larger pieces and duct tape to collect the smaller pieces and then wipe with a damp cloth. This process will remove almost all the mercury which attaches to the phosphor powder, broken glass, and metal.
- Step 3: Once you've picked up any visible pieces and wiped the area, you can vacuum with the windows open. This allows any vapors created by vacuuming to be diluted. Vacuuming before a complete clean up causes more mercury to vaporize into the air. Then, take the vacuum outside to change the bag or empty the canister.
- Step 4: Place fragments, damp cloth, and vacuum cleaner bag in a sealed plastic bag and store outside in a safe place away from children until your next trip to the household hazardous waste center. Be sure to wash your hands after clean up.
Minnesota Family Environmental Exposure Tracking:
The Minnesota Family Environmental Exposure Tracking (MN FEET) studied mercury, lead, and cadmium in Minnesota women and their babies. MN FEET will help families and communities protect their babies from these chemicals.
Mercury in Newborns in the Lake Superior Basin Study:
The Mercury in Newborns in the Lake Superior Basin study was conducted to assess population-level mercury exposures of newborn infants within the Lake Superior Basin.
Mercury Flooring Testing and Mitigation:
The following health consultation, Bethel University: Emissions from a Mercury-containing Gymnasium Floor: Mitigating exposures from mercury-containing polymer floors, Feb. 2008 (PDF), provides technical information about emission and exposure models. MDH also developed guidance for controlling or mitigating mercury vapor exposures from mercury-emitting floors in the past. View the Mercury Flooring Testing and Mitigation: Guidance for Environmental Professionals (PDF). (This guidance is not currently being supported or updated.)
- Minnesota Pollution Control Agency: Mercury
- U.S. Environmental Protection Agency: Mercury in Your Environment
- U.S. Agency for Toxic Substances and Disease Registry: Mercury
For questions about exposure, please contact us.