Mercury: facts & figures
Total blood mercury levels in the U.S. population
Adults have higher total mercury levels in their blood than children. Because clearance of mercury from the body is slow, blood levels increase as children get older.
For each group, the median is a total blood mercury level that 50% of people tested fall above and 50% of people tested fall below. The 95th percentile is a total blood mercury level that 95% of people fall below. It shows mercury levels in the most highly exposed people.
Mercury in young children is concerning because their bodies and brains are still developing and hand-to-mouth behaviors increase the risk of coming into contact with chemicals.
Levels of total mercury in children with the highest exposures, the 95th percentile, have gone down since 1999-2000. Median blood levels have stayed about the same. In years without a datapoint, the median blood level was below the laboratory limit of detection.
Mercury in women of childbearing age is concerning because mercury a woman comes into contact with during pregnancy can cross the placenta. High levels may cause health effects in the baby.
The median mercury level did not change much between 1999 and 2010, while the 95th percentile level dropped significantly. Total blood mercury is usually composed mostly of methylmercury. Methylmercury levels below 5.8 micrograms (mcg) per liter (L) are considered safe.
Mercury levels are higher in Asians compared to other racial/ethnic groups. This disparity is largely due to differences in methylmercury levels. The 95th percentile level in Asians is much higher than the level considered safe for sensitive populations like pregnant women and children.
Mercury is a metal that has several chemical forms. Exposure to all forms of mercury may increase the risk of health problems.
The 3 forms of mercury people most frequently come into contact with are:
- Methylmercury: People come into contact with methylmercury from eating fish higher in mercury like walleye and swordfish. Consuming fish lower in mercury, like salmon and crappies, is good for your health.
- Elemental mercury: People can come into contact with elemental mercury through their dental fillings. This is not a large amount of mercury and is generally not a health concern. People can also be exposed to elemental mercury from broken thermometers, broken fluorescent bulbs, religious and cultural ampules, and imported ethnic medicines and products like some skin lightening creams.
- Inorganic mercury: People come into contact with inorganic mercury through the use of some skin lightening creams.
Babies in utero and young children are most at risk because methylmercury and elemental mercury can impact the developing brain and nervous system, affecting learning abilities, memory, and attention. In adults and children, ongoing exposure to elemental and inorganic mercury can also damage the nervous system and the kidneys.
Biomonitoring measures mercury in people
Mercury can be measured in blood, urine or hair to determine the level in a person's body.
The U.S. Environmental Protection Agency (EPA) has determined that methylmercury levels up to 5.8 micrograms (mcg) per liter (L) of blood are "safe". Even though some fish are a source of methylmercury, regular consumption of fish known to be lower in mercury is an important part of a healthy diet.
What is being done about mercury in Minnesota?
- MDH uses biomonitoring to measure mercury in vulnerable Minnesotans: Lake Superior Mercury Biomonitoring Project, Pregnancy and Newborns Exposure Study, and Minnesota Family Environmental Exposure Tracking (MN FEET).
- MDH's Fish Consumption Advisory Program provides advice for how much fish is safe to eat. In addition, MDH provides health and exposure information on mercury in the environment.
- The Minnesota Pollution Control Agency works to reduce mercury use and contamination.