A new government study revealed widespread mercury contamination of fish tested in streams across the U.S.¹ In the most comprehensive study of its kind to date, scientists from the U.S. Geological Survey tested more than 1,000 fish from nearly 300 streams across the nation from 1998 to 2005.

Every fish tested showed traces of mercury and a quarter of the fish tested had higher amounts of mercury than the Environmental Protection Agency (EPA) deems safe to eat. Fetuses, infants, and young children are at greatest risk for harm from mercury, which can damage developing brains and nervous systems.

“This study shows just how widespread mercury pollution has become in our air, watersheds and many of our fish in freshwater streams,” Interior Secretary Ken Salazar said in a statement. “This science sends a clear message that our country must continue to confront pollution, restore our nation’s waterways and protect the public from potential health dangers.”

Just as it is in fish, mercury is stored in our bodies.  A study published on the heels of the Geological Survey Report suggests a considerable rise in the level of mercury over the last decade.²  The study from the University of California, Los Angeles (UCLA) of more than 6,000 American women, found evidence linking inorganic mercury in the liver, immune system and pituitary gland; tissues known to be targets for the toxin.

Author and neuroscience researcher, Dan R. Laks used data from the U.S. Centers for Disease Control and Prevention’s National Health Nutrition Examination Survey (NHANES) finding that while inorganic mercury was detected in the blood of 2 percent of women aged 18 to 49 in the 1999-2000 NHANES survey, that level rose to 30 percent of women by 2005-2006.

Environmental sources of mercury also include coal-fired electricity plants, air transport, mining and waste incineration. Wetlands, forests and organic soils can enhance the conversion of mercury to highly toxic methylmercury, which accumulates in the food chain and can cause serious public health problems.

Chronic mercury exposure has been linked to an increased risk for autism, mental impairment and neurodegenerative disorders such as Alzheimer’s disease.³

The study also found a connection between the levels of pituitary hormone lutropin and chronic mercury exposure. Inorganic mercury can accumulate in the brain and stay there for years, which may help explain mercury’s link to neurodegenerative disease.

“These results suggest that chronic mercury exposure has reached a critical level where inorganic mercury deposition within the human body is accumulating over time,” Laks said. “It is logical to assume that the risks of associated neurodevelopmental and neurodegenerative disease will rise as well.”

Sources:

1. Scudder, B.C., Chasar, L.C., Wentz, D.A., Bauch, N.J., Brigham, M.E., Moran, P.W., and Krabbenhoft, D.P., Mercury in fish, bed sediment, and water from streams across the United States, 1998–2005. U.S. Geological Survey Scientific Investigations Report 2009–5109, 74 p., August 2009
2. Laks, Dan R. Assessment of chronic mercury exposure within the U.S. population, National Health and Nutrition Examination Survey, 1999–2006. Biometals. August 2009
3. Palmer R.F., Blanchard S., Stein Z., Mandell D., Miller C. Environmental mercury release, special education rates, and autism disorder: An ecological study of Texas. (2006) Health and Place, 12 (2), pp. 203-209.