Methylmercury's toxic toll

1:06pm, March 25, 2003

More than 60,000 children are born each year in the United States with neurodevelopmental impairments caused by exposure in the womb to methylmercury compounds, according to new estimates by an expert panel convened by the National Academy of Sciences. The panel released its 290-page review of methylmercury's toxicity earlier this month.

Many industrial processes, especially fossil-fuel burning, spew inorganic mercury into the air. Once it rains down, the pollutant usually undergoes a chemical transformation—methylation—into a much more toxic form. Fish and other aquatic life readily pick up and store the resulting methylmercury (MeHg) in their fat (SN: 3/9/91, p. 152).

At highest risk, therefore, are children whose mothers ate large amounts of tainted fish and other seafood during pregnancy. Because fish provide a host of healthy nutrients, the panel argues that the long-term goal should be reducing MeHg concentrations in U.S. fish, not cutting fish from the diet.

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