One in every five women of childbearing age who chose to have their hair tested for mercury showed levels of the toxic metal above the federal government's acceptable limit of 1 µg/g, according to a study released February 8th by two environmental groups.
More than 6,500 people participated, making it the nation’s largest mercury hair sampling project, according to the Sierra Club
, which helped recruit participants. The interim report
of this ongoing study conducted at a UNC Asheville lab. said that fish consumption is the primary source of hair mercury exposure for most Americans as indicated by the fact that women who ate fish at least twice a week had the highest mercury levels.
“That’s what surprised me - how strong that relationship is,” said Steve Patch
, director of UNC Asheville’s Environmental Quality Institute that conducted the study for Greenpeace and the Sierra Club. While the study might not be representative of the overall population because the participants asked to participate, still the results suggest that many Americans could unknowingly be at risk from mercury exposure. "This is clearly a widespread problem in our country," said Steve Patch, the report's lead author. Background
Mercury is a global pollutant. Coal burning power plants account for about 40 percent of the mercury emissions in the U.S. The pollutant gets into the air and then into lakes and streams, where it gradually moves up the food chain. It’s of special concern for women who are pregnant: Children exposed in the womb to relatively high levels of methylmercury - the highly toxic form of mercury - have shown delayed onset of walking and talking and deficits in learning ability, according to the Environmental Protection Agency.The Study
The study started in July 2004, when representatives of Greenpeace
and Sierra Club
started handing out kits encouraging people to have their hair tested for its mercury content. Analyzing locks of hair is a scientifically accepted method that can measure long-term exposure to the metal retrospectively. Of the 2,834 women ages 16-49 who were tested, 23 percent had mercury levels above 1 µg/g, a reference dose considered to be a safety limit developed by the U.S. Environmental Protection Agency. Correlation between Fish Meals and Mercury Intake
Medical experts agree eating fish provides many benefits. But the new research is the latest to find high levels of mercury in people who routinely ate fish, the chief source of exposure to the toxic metal. Mercury can affect the development of fetuses and young children as well as cause neurological problems in adults. A study last year by researchers for the state of Wisconsin also found a correlation between mercury levels and the number of times participants ate fish during a month. In that study, funded with federal and state grants, 29 percent of the men and 13 percent of the women who volunteered to be tested had mercury levels above the EPA limit.Opinion of the seafood industry
Representatives of the seafood industry contend there is nothing to worry about. "The health benefits associated with eating fish far outweigh any potential risk from such minimal exposure to mercury," John Connelly, president of the National Fisheries Institute, wrote in a recent letter to the Chicago Tribune.
A scientist who wasn't involved in either study said the results should bolster efforts in the United States and other countries to limit sources of mercury, including emissions from coal-fired power plants. "There is tremendous value in eating fish, but to force people to make these tradeoffs isn't appropriate," said John Spengler
, a professor at the Harvard School of Public Health. The original report of the study Steven C. Patch, Richard P. Mass, Kimberly R. Sergent, An investigation of factors related to levels of mercury in human hair, Technical Report #05-150, Environ. Qual. Inst., Univ. N.Carolina, Oct. 2005Related information
M.A. McDowell, C.F. Dillon, J. Osterloh, P.M. Bolger, E. Pellizzari, R. Fernando, R. Montes de Oca, S.E. Schober, T. Sinks, R.L. Jones, K.R., Hair Mercury Levels in U.S. Children and Women of Childbearing Age: Reference Range Data from NHANES 1999-2000
, Environ. Health Perspect., 112/11 (2004) 1165-1171: DOI:
Génon Jensen, Karolina Ruzickova, HALTING THE CHILD BRAIN DRAIN - Why we need to tackle global mercury contamination, Report, Health and Environment Alliance (HEAL) and Health Care Without Harm Europe (HCWH), December 2006
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Link database: Toxicity of Organic mercury compounds
Link database: Human exposure to methylmercury via the diet
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April 27, 2004: FDA/EPA recommends pregnant women to restrict their fish consumption because of methylmercury content
last time modified: June 20, 2020