FAQs about mercury
- What should I do if mercury gets spilled?
- Is there mercury in the fish in my lake?
- What health problems can mercury cause?
- Does mercury cause cancer?
- How do scientists detect mercury poisoning?
- How can you tell that a lake is contaminated with mercury?
- Why isn't there just one fish consumption advisory for all of Minnesota?
- Would it be better if I just didn't eat any fish?
- Is there mercury in ocean fish too?
- What should I do with thermometers and other items in my home that contain mercury?
- Do all scientists agree about the dangers of mercury?
- What are other states doing about mercury?
- Why don't we just stop burning coal?
- Why don't we just stop burning garbage?
Spilled mercury, even small quantities in the home, should be cleaned up properly so that people don't come in contact with it or breathe its vapors. Some ordinary cleanup measures such as sweeping and vacuuming can actually increase the risks.
Mercury vapor is odorless, colorless and very toxic. Even though liquid mercury evaporates slowly, a significant amount of mercury vapor can build up in indoor air at room temperature after some is spilled—it can be dangerous to breathe these mercury vapors.
Households: Call the Minnesota Duty Officer at 800-422-0798 or 651-649-5451 and report the spill. The Duty Officer will put you in touch with someone who can advise you on dealing with the spill. Or, follow the directions in the following fact sheet:
Commercial/Industrial: If mercury has been spilled at your commercial or industrial site, contact the Minnesota Duty Officer at 651-649-5451 or 800-422-0798.
The Minnesota Department of Health publishes a booklet every year that shows how much fish of various kinds and sizes can safely be eaten from lakes from which fish have been tested. To get a copy, call 651- 215-0700 or (800) 657-3908, toll-free. Or you can look up the characteristics of particular lakes, including any information available on fish consumption advisories, on the Minnesota Department of Natural Resources' web site.
Information on the health problems that mercury can cause can be found at:
The U.S. Environmental Protection Agency classifies mercury as a possible human carcinogen. So far, data are unsufficient to determine conclusively whether it causes cancer. However, it also appears that serious nerve damage would result from exposures to mercury much lower than the levels that might cause cancer.
Mercury poisoning can be detected through blood tests. Scientists also can detect exposures to mercury in the recent past by chemical analysis of human hair, because mercury is excreted from the body, in part, through the hair.
It isn't possible to tell without conducting scientific analyses of the water, fish or sediments. Nothing in a lake's outward appearance is likely to indicate whether the lake or its fish are contaminated, or the extent to which they might be contaminated.
Certain characteristics of lakes, such as the run-off area, acidity or alklalinity, adjacent wetlands, and biological activity in the lake all affect the level of methylmercury contamination in the lakes' fish. The Minnesota Department of Health believes that fish consumption guidelines should take into consideration the data available on fish contamination, since the fish from two lakes very near each other may have very different levels of methylmercury contamination. Levels of contaminants, including mercury and other PBTs, in Minnesota fish are measured by the Minnesota's Fish Contaminant Monitoring Program.
In addition, people who eat sport-caught fish only while on vacation or during a particular season don't need to follow the same consumption guidelines as those who eat such fish frequently all year. And consumption-advisory limits are more restrictive for children and women of child-bearing age.
Fish are low in fat and a good source of protein and other nutrients. According to the U.S. Environmental Protection Agency's recent report to Congress on mercury, most people in the United States can eat fish without worrying about mercury contamination.
Ocean fish can be contaminated with mercury as well as freshwater fish, although mercury levels tend to be lower. Again, fish that eat other fish (such as tuna, shark and king mackerel) will have the highest mercury levels.
Household items containing mercury should be taken to your county's household hazardous waste disposal site. It is unlawful to place them in ordinary household garbage. Call your county's solid waste officer for the location and hours of the site nearest you.
While all scientists agree that mercury is toxic, they do not all agree on the amount of mercury that should be considered a human health hazard. Both the U.S. Environmental Protection Agency and the Minnesota Department of Health have calculated limits to mercury consumption using an approach that allows for human variability in how the body responds to mercury. This method is most likely to be over-protective rather than under-protective of human health.
A number of other states have begun studying the problem of mercury contamination in lakes and fish. As might be expected, the states most interested are those in which fishing is an important recreation. The states surrounding the Great Lakes have formed an organization and signed agreements with Canada to reduce toxic contamination of Great Lakes waters. Minnesota has been one of the leading states in studying mercury contamination and developing programs to keep mercury out of the environment.
Much easier said than done. We are dependent on coal for much of our electricity, and coal contains varying amounts of mercury, depending on its source. When it is burned, some of the mercury is captured by pollution-control equipment and some is released to the air.
It is possible to create electricity using other fuels with less mercury content. Electricity also can be produced by other means, such as wind and solar power, but burning coal remains the cheapest way to produce electricity. Some Minnesota utilities are beginning to produce electricity in ways that release less mercury, but many existing power plants are constructed to burn coal. Minnesota utilities are participating in the MPCA's mercury reduction initiative, in an effort to find the most cost-effective way to keep mercury out of the environment.
In 2003, 36% of the garbage collected in Minnesota was sent to resource recover facilities. Garbage sent to these facilities it burned under strictly controlled conditions and the resulting heat is used to generate 100 megawatts of electricity and heat buildings. In addition to this renewably-generated energy, these resource recovery facilities diverted over 100 million tons of waste from Minnesota landfills. While there are mercury emissions associated with burning garbage, emissions have decreased significantly in the past 15 years. Since 1990 resource recovery facilities have added pollution control equipment and the mercury content of the incoming garbage has also been reduced. As a result of these actions mercury emissions have reduced by over 95% from 1,800 pounds in 1990 to about 87 pounds in 2004.