Mercury: Facts & Figures

Blood mercury levels in the U.S. population


Blood mercury levels in the U.S. population, by age

Data are from the 2009-2010 National Health and Nutrition Examination Survey (NHANES), conducted by the U.S. Centers for Disease Control and Prevention (CDC). Median levels for 1-5 years were below the laboratory's limit of detection.

Adults have higher levels of mercury levels in their blood than children. Blood levels increase as children get older. But, although the median value for children 1-5 was below the detection limit, 5% of them had mercury levels above 1.3 µg/L. Additionally, 5% of adults had blood levels above 5.8 µg/L, the reference dose for mercury. Having blood mercury above this level is potentially unsafe.


Children in 95th percentile, by year

Data are for children age 1-5 from two-year cycles of NHANES.

The 95th percentile represents people with the highest blood mercury levels. Looking at the 95th percentile for children 1-5, mercury levels clearly declined between 2000 and 2010.


Women of childbearing age with mercury levels above health concern level

Data are for women age 16-49 and are from a paper by Mahaffey et al. (2009) that used two-year cycles of NHANES data.

Because babies in utero are particularly vulnerable, mercury exposure is a concern for women of childbearing age. The percent of women 16-49 with mercury levels higher than the reference dose declined from 2000-2004. However, in 2004, over 2% of women in this age group had potentially unsafe blood mercury levels that could harm their developing babies.


Women of childbearing age with mercury levels above health concern level, by race

Data are for women age 16-49 and are from a paper by Mahaffey et al. (2009) that used 1999-2004 NHANES data.

A lower percentage of Mexican American and other Hispanic women had potentially unsafe blood mercury levels (above 5.8 µg/L) compared to the other groups. Nearly 16% of women who identified themselves as "other race," which included Asian, Native American, Pacific Islander, and Caribbean, had blood mercury levels above 5.8 µg/L.


Mercury is a metal that can harm your health.

Mercury is a metal that has several chemical forms. Exposure to all forms of mercury may increase the risk of health problems.

Babies in utero and young children are most at risk because both 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.

Fish consumption is a source of exposure to methylmercury. Older, larger fish and fish that eat other fish (predators like large walleye, large lake trout and swordfish) have the highest levels of mercury. People can also be exposed to elemental and inorganic mercury in broken thermometers, broken fluorescent lightbulbs, some skin lightening creams, and through some cultural and religious rituals.

Biomonitoring measures mercury in people.

The U.S. Environmental Protection Agency (EPA) has determined that 5.8 micrograms (µg) of mercury per liter (L) of blood represents a "safe" level, of exposure to methylmercury. Regular consumption of low mercury-containing fish (such as salmon, bluegill and crappies) is an important part of a healthy diet.

The EPA has also determined that 300 nanograms per cubic meter is a “safe” elemental mercury concentration in air (Reference Concentration). Urine mercury levels above 1 µg/L may suggest an ongoing exposure above this Reference Concentration.

What is being done about mercury in Minnesota?